🏷

Classifications

Harrison's Part

⚙

Pathophysiology

6

Gastrointestinal Barrier Failure

A full-thickness gastrointestinal defect, anastomotic leak, biliary leak, or penetrating injury breaches the normally sterile peritoneal compartment and delivers bacteria or inflammatory luminal contents onto the peritoneal surface.

peritoneum UBERON:0002358

Downstream

Polymicrobial Peritoneal Seeding The barrier breach delivers enteric aerobic and anaerobic organisms into peritoneal fluid and onto mesothelial surfaces.

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"Secondary peritonitis is traditionally defined as inflammation of the peritoneal cavity secondary to the loss of integrity of a hollow viscus or a chemically irritating leakage of biological fluids onto the peritoneum."

The review identifies hollow-viscus disruption and leakage of biological fluid as sources for secondary peritoneal inflammation and infection.

Polymicrobial Peritoneal Seeding

Feculent or purulent contamination introduces mixed aerobic and anaerobic communities, including Enterobacterales and Bacteroides, into the peritoneal space.

peritoneal fluid UBERON:0001268

Animal models

Cecal ligation and puncture mouse Mouse partially recapitulates CLP seeds cecal contents into the mouse peritoneum and produces polymicrobial intraperitoneal sepsis.

Downstream

Mesothelial Innate Cytokine Release Bacterial products contact mesothelial and resident innate immune cells, which respond by releasing inflammatory mediators.

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"In peritonitis, the peritoneal cavity hosts diverse, often polymicrobial communities, with complex interactions between aerobic and anaerobic bacteria, as well as fungi."

The review summarizes the fecal-contamination variant of secondary peritonitis as an enteric polymicrobial process.

Mesothelial Innate Cytokine Release

Peritoneal mesothelial cells sense microbial products, release IL-6, IL-8, TNF, CXCL1, and CCL2, and start the chemokine gradient that recruits neutrophils into the infected peritoneum.

mesothelial cell CL:0000077

inflammatory response GO:0006954 ↑ INCREASED

Downstream

Purulent Peritoneal Inflammation Mesothelial cytokine and chemokine release promotes recruitment of neutrophils into the peritoneal cavity.

Abdominal Sepsis Peritoneal innate immune activation can spread systemically as a dysregulated host response with organ dysfunction.

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"Mesothelial cells are front-line sentinels releasing IL-6, IL-8, tumor necrosis factor (TNF)-α, CXCL1 and CCL2 after exposure to microbial products"

The review directly connects microbial exposure at the peritoneum with mesothelial release of neutrophil-recruiting and proinflammatory mediators.

Purulent Peritoneal Inflammation

Bowel-content contamination generates purulent peritoneal inflammation that produces local acute-abdomen signs and can progress systemically when source control and antimicrobial therapy do not interrupt it.

inflammatory response GO:0006954 ↑ INCREASED

Downstream

Fibrinous Loculation and Abscess Formation Peritonitis favors peritoneal coagulation and impaired fibrin clearance, promoting loculated abscess formation.

Abdominal Sepsis Uncontrolled local bacterial infection can spread into a systemic septic host response.

Abdominal pain Peritoneal irritation produces the abdominal pain and tenderness of an acute abdomen.

Hypoactive bowel sounds Purulent peritoneal inflammation impairs bowel motility and produces diminished or absent bowel sounds.

Abdominal guarding Peritoneal inflammation irritates the abdominal cavity and produces local guarding or rigidity.

Abdominal distention Peritoneal inflammation produces distention and diminished bowel sounds as acute-abdomen manifestations.

Fever Local peritoneal infection drives systemic inflammatory signs including fever.

Tachycardia Local peritoneal infection can progress to systemic inflammation with tachycardia.

Dehydration Acute perforation peritonitis can present with dehydration during the systemic inflammatory acute-abdomen syndrome.

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"This section groups the condition into five archetypal variants, namely fibrinous mainly related to peptic ulcer perforation (PUP), purulent either due to colonic or non-colonic perforation"

This review places purulent secondary peritonitis within the diffuse forms produced by visceral-barrier breach.

Fibrinous Loculation and Abscess Formation

The inflamed abdominal cavity develops impaired fibrin degradation, walling off infection into adhesions and abscesses but also creating protected infectious foci.

peritoneum UBERON:0002358

Show evidence (1 reference)

PMID:12734857 SUPPORT REVIEW SYNTHESIS Other

"Diminished fibrin degradation is a common pathway for the formation of adhesions and abscesses."

This review connects impaired abdominal fibrin degradation to the adhesion and abscess formation that creates loculated infectious foci during peritonitis.

Abdominal Sepsis

Failure to control the intra-abdominal source allows inflammatory mediator spillover and bacterial products to drive life-threatening organ dysfunction as abdominal sepsis.

Downstream

Sepsis Intra-abdominal infection can drive the dysregulated systemic host response and organ dysfunction that define sepsis.

Shock Severe intra-abdominal sepsis can progress to septic shock.

Show evidence (1 reference)

PMID:30685836 SUPPORT REVIEW SYNTHESIS Other

"Sepsis-3 defines sepsis as a life-threatening organ dysfunction caused by a dysregulated host response to infection."

This review applies the Sepsis-3 organ-dysfunction definition to intra-abdominal infection.

⬡

Pathograph

Use Group by to collapse related nodes into one box. Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

9

Cardiovascular 2

Shock HP:0031273

Show evidence (1 reference)

PMID:24392388 SUPPORT PRIMARY RESULT Human clinical

"Abdominal guarding was present in 97.14% patients followed by diminished or absent bowel sound (57.14%), shock (54.29%)."

This 490-patient perforation-peritonitis cohort reported shock in more than half of patients.

Tachycardia HP:0001649

Show evidence (1 reference)

PMID:24392388 SUPPORT PRIMARY RESULT Human clinical

"diminished or absent bowel sound (57.14%), shock (54.29%). tachycardia (54.28%), dehydration (52.85%)"

This 490-patient perforation-peritonitis cohort reported tachycardia in more than half of patients.

Digestive 2

Hypoactive bowel sounds HP:0030144

Show evidence (1 reference)

PMID:24392388 SUPPORT PRIMARY RESULT Human clinical

"diminished or absent bowel sound (57.14%), shock (54.29%). tachycardia (54.28%), dehydration (52.85%)"

This 490-patient perforation-peritonitis cohort reported diminished or absent bowel sounds in more than half of patients.

Abdominal distention HP:0003270

Show evidence (1 reference)

PMID:24392388 SUPPORT BACKGROUND Human clinical

"Local findings include abdominal tenderness, guarding or rigidity, distension, diminished bowel sounds."

This cohort-study introduction lists abdominal distension among local findings in perforation peritonitis.

Immune 1

Sepsis HP:0100806

Show evidence (1 reference)

PMID:30685836 SUPPORT REVIEW SYNTHESIS Other

"The abdomen is the second most common source of sepsis and is associated with unacceptably high morbidity and mortality."

Identifies the abdomen as a major sepsis source, supporting sepsis as a key systemic manifestation of septic peritonitis and other abdominal infections.

Metabolism 2

Fever HP:0001945

Show evidence (1 reference)

PMID:24392388 SUPPORT BACKGROUND Human clinical

"Systemic findings include fever, chills or rigor, tachycardia, sweating, tachypnea, restlessness, dehydration, oliguria, disorientation and ultimately shock"

The cohort-study introduction lists fever among the systemic findings in perforation peritonitis.

Dehydration HP:0001944

Show evidence (1 reference)

PMID:24392388 SUPPORT PRIMARY RESULT Human clinical

"diminished or absent bowel sound (57.14%), shock (54.29%). tachycardia (54.28%), dehydration (52.85%)"

This 490-patient perforation-peritonitis cohort reported dehydration in more than half of patients.

Constitutional 2

Abdominal pain HP:0002027

Show evidence (1 reference)

PMID:24392388 SUPPORT BACKGROUND Human clinical

"Peritonitis usually presents as an acute abdomen. Local findings include abdominal tenderness, guarding or rigidity, distension, diminished bowel sounds."

The cohort-study introduction lists abdominal tenderness among the local acute-abdomen signs of peritonitis.

Abdominal guarding HP:0032546

Show evidence (1 reference)

PMID:24392388 SUPPORT PRIMARY RESULT Human clinical

"Abdominal guarding was present in 97.14% patients followed by diminished or absent bowel sound (57.14%), shock (54.29%)."

This 490-patient perforation-peritonitis cohort reported abdominal guarding in nearly all cases.

💊

Medical Actions

2

Surgical Source Control

Action: Surgical source control Ontology label: Surgical Procedure NCIT:C15329

Platform: Surgery

Surgical or percutaneous source control reduces microbial burden by repairing, resecting, draining, debriding, decompressing, or removing the anatomic source of peritoneal contamination.

Mechanism Target:

INHIBITS Gastrointestinal Barrier Failure — Source control closes or removes the leak that continues to seed the peritoneum.

INHIBITS Fibrinous Loculation and Abscess Formation — Drainage and debridement evacuate infected loculated collections and remove necrotic foci that preserve bacterial burden.

Show evidence (1 reference)

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"The aim of source control is to reduce microbial load by removing the infection source and it is achievable by using a wide range of procedures, such as definitive surgical removal of anatomic infectious foci, percutaneous drainage and toilette of infected collections, decompression, and..."

Defines source control across surgical removal, drainage, decompression, debridement, and device removal for intra-abdominal infection.

Broad-Spectrum Antimicrobial Therapy

Action: Antibiotic Therapy NCIT:C15620

Platform: Small molecule

Antimicrobial therapy suppresses enteric Gram-negative and anaerobic organisms seeded into the peritoneal cavity; regimen choice is guided by clinical status, local resistance epidemiology, and risks for multidrug-resistant bacteria or Candida.

Mechanism Target:

INHIBITS Polymicrobial Peritoneal Seeding — Antimicrobial therapy inhibits or kills the organisms seeded into the peritoneal cavity while surgical source control removes the source.

Show evidence (3 references)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"The treatment of secondary peritonitis relies on two fundamental principles: rapid surgical source control even with intraperitoneal negative-pressure therapy and effective antimicrobial therapy"

Summarizes antimicrobial therapy as one of the two fundamental treatment principles for secondary peritonitis.

PMID:27670577 SUPPORT PRIMARY RESULT Human clinical

"A short course of antibiotics in complicated intra-abdominal infection with source control seems to have similar outcomes to a longer course in patients with diabetes, obesity, or increased severity of illness."

A STOP-IT trial subgroup analysis supports limiting antibiotic duration after source control, including in high-risk complicated intra-abdominal infection.

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"Antibiotic and antifungal regimens in patients with IAIs should be based on the resistance epidemiology, clinical conditions, and risk for multidrug resistance (MDR) and Candida spp. infections."

Supports selecting antimicrobial regimens by resistance epidemiology, clinical status, and multidrug-resistance or Candida risk.

🔬

Biochemical Markers

2

Procalcitonin

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"Biomarkers such as procalcitonin (PCT), interleukin-6 (IL-6), high mobility group box 1 (HMGB1), C-reactive protein (CRP), lipopolysaccharide (LPS), neutrophil-to-lymphocyte ratio (NLR), and neutrophil gelatinase-associated lipocalin (NGAL) have emerged as tools for early diagnosis, subtype..."

The review identifies procalcitonin among the secondary-peritonitis biomarkers with diagnostic, stratification, and treatment-monitoring use.

C-reactive protein

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"Biomarkers such as procalcitonin (PCT), interleukin-6 (IL-6), high mobility group box 1 (HMGB1), C-reactive protein (CRP), lipopolysaccharide (LPS), neutrophil-to-lymphocyte ratio (NLR), and neutrophil gelatinase-associated lipocalin (NGAL) have emerged as tools for early diagnosis, subtype..."

The review identifies CRP among secondary-peritonitis biomarkers used for diagnosis, subtype stratification, and response monitoring.

🔬

Diagnosis

2

Clinical and plain-film acute-abdomen assessment

Perforation peritonitis is initially assessed from the acute history, physical examination, and erect abdominal X-ray evidence of pneumoperitoneum while the team triages the perforated or infected source.

Show evidence (1 reference)

PMID:24392388 SUPPORT PRIMARY RESULT Human clinical

"Initial diagnosis was made on the basis of detailed history, clinical examination and presence of pneumoperitoneum on erect abdominal X-ray."

A 490-patient perforation-peritonitis cohort documents an initial diagnostic assessment combining history, examination, and erect abdominal radiography for pneumoperitoneum.

Abdominal CT source localization

Abdominal CT is used in the emergency workup to help diagnose severe intra-abdominal sepsis and localize the perforated or infected source for source-control planning.

Computed Tomography NCIT:C17204

Show evidence (1 reference)

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"A prompt diagnosis of severe IAS often requires an adequate clinical evaluation, laboratory tests, and imaging exams, such as abdominal ultrasound or Computed Tomography (CT), which are among the most used diagnostic procedures in emergency settings"

This source-control review identifies CT and ultrasound among emergency diagnostic procedures for severe intra-abdominal sepsis.

📈

Progression

4

Visceral breach and peritoneal contamination

Secondary septic peritonitis begins when loss of gastrointestinal integrity or another intra-abdominal source exposes the peritoneum to enteric organisms and inflammatory luminal contents.

Show evidence (1 reference)

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"Secondary (the most common ones): derived from loss of integrity of the gastrointestinal tract."

This source-control review distinguishes secondary peritonitis from primary and tertiary infectious peritonitis by its origin in a gastrointestinal integrity defect.

Localized or diffuse purulent peritonitis

Enteric contamination can remain localized or extend through the peritoneal cavity as fibrinous, purulent, or stercoraceous secondary peritonitis.

Show evidence (1 reference)

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"Intra-abdominal infections can be categorized as uncomplicated if they affect just one organ and do not spread to the peritoneum, or complicated if the infection spreads to the peritoneum, causing localized or diffuse peritonitis"

The review records localized and diffuse peritonitis as the peritoneal extension states of complicated intra-abdominal infection.

Intra-abdominal sepsis and septic shock

Ongoing abdominal infection can cross from local purulent inflammation into dysregulated systemic inflammation, organ dysfunction, and septic shock.

Show evidence (1 reference)

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"Clinical manifestations are widely varied and IAS, especially if poorly managed, can cause immune response deregulation leading to septic shock."

The review describes progression from intra-abdominal sepsis toward septic shock when the abdominal infection is not adequately managed.

Source-controlled resolution or persistent infection

Successful source control removes the leaking or infected focus; failure to eliminate the source can leave persistent abscesses, chronic inflammation, or recurrent tertiary peritonitis after apparently adequate surgery.

Show evidence (2 references)

PMID:8891619 SUPPORT PRIMARY RESULT Human clinical

"In 37 of the patients the source of infection was eliminated resulting in 7 deaths (19%); all 11 of those in whom it was not eliminated died."

This postoperative intra-abdominal infection cohort links source elimination to survival and identifies failure to eliminate the source as a terminally poor-prognosis course.

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"Tertiary: recurrent peritoneal infection which occurs more than 48 h after apparently successful and adequate surgical source control of secondary peritonitis"

This review defines tertiary peritonitis as a recurrent outcome after attempted source control of secondary peritonitis.

🦠

Infectious Agent

2

Escherichia coli

Escherichia coli is an enteric aerobic Gram-negative bacterium recovered in polymicrobial purulent secondary peritonitis after gastrointestinal leakage.

Escherichia coli NCBITaxon:562

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"In intra-abdominal infections, the peritoneal microbiome reflects the contaminating intestinal microbiome, with a predominance of enteric Gram-Negative bacteria (Escherichia coli, Klebsiella spp., Enterobacter spp.), anaerobes (Bacteroides fragilis, Clostridium spp.), and Gram-Positive bacteria..."

The secondary-peritonitis review lists E. coli and other aerobic Gram-negative taxa among the organisms in purulent secondary peritonitis.

Bacteroides fragilis

Bacteroides fragilis is an enteric anaerobe that contributes to the polymicrobial communities recovered in secondary peritonitis after fecal or lower-intestinal contamination.

Bacteroides fragilis NCBITaxon:817

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"In intra-abdominal infections, the peritoneal microbiome reflects the contaminating intestinal microbiome, with a predominance of enteric Gram-Negative bacteria (Escherichia coli, Klebsiella spp., Enterobacter spp.), anaerobes (Bacteroides fragilis, Clostridium spp.), and Gram-Positive bacteria..."

The review identifies B. fragilis among anaerobes recovered from intra-abdominal infection.

↔️

Transmission

1

Endogenous peritoneal inoculation

Septic peritonitis is not spread as a person-to-person syndrome; it usually begins when a hollow-viscus leak, surgical dehiscence, biliary leak, or other intra-abdominal source inoculates the peritoneal cavity with organisms from the patient's own gastrointestinal tract or biliary tract.

Show evidence (1 reference)

PMID:41227298 SUPPORT REVIEW SYNTHESIS Other

"Secondary peritonitis is traditionally defined as inflammation of the peritoneal cavity secondary to the loss of integrity of a hollow viscus or a chemically irritating leakage of biological fluids onto the peritoneum."

This definition identifies visceral or fluid leakage into the peritoneum as the usual initiating exposure for secondary septic peritonitis.

⚖️

Clinical Burden

High

Complicated intra-abdominal infection that reaches the peritoneal cavity can become abdominal sepsis with substantial in-hospital mortality; adequate source control is a dominant determinant of survival.

Show evidence (2 references)

PMID:39200076 SUPPORT REVIEW SYNTHESIS Other

"Intra-abdominal infections (IAIs) account for a major cause of morbidity and mortality, representing the second most common sepsis-related death with a hospital mortality of 23-38%."

This 2024 review quantifies the clinical burden of intra-abdominal infection, the disease class that includes peritoneal spread with localized or diffuse peritonitis.

PMID:8891619 SUPPORT PRIMARY RESULT Human clinical

"In 37 of the patients the source of infection was eliminated resulting in 7 deaths (19%); all 11 of those in whom it was not eliminated died."

A postoperative intra-abdominal infection cohort links elimination of the infectious source to survival, supporting the high burden of disease when source control fails.

🐁

Animal Models

1

Cecal ligation and puncture mouse

Cecal ligation and puncture is a standard adult mouse model of polymicrobial intraperitoneal sepsis induced by surgical cecal injury, but the devitalized cecum leaves an uncorrected source that prevents the model from representing source-controlled clinical resolution.

Species

Mouse

Publication

PMID:34048005

Pathograph links

Polymicrobial Peritoneal Seeding partially recapitulates fidelity: moderate observes: organism CLP seeds cecal contents into the mouse peritoneum and produces polymicrobial intraperitoneal sepsis.

Limitations: The devitalized cecum remains in place, so CLP does not model an episode where surgical source control closes or removes the leaking focus.

Divergences from the human mechanism

boundary omission qualifying

Definitive source control is outside the CLP model boundary even though source repair or removal is central to the human secondary-peritonitis course and treatment strategy curated here.

Show evidence (2 references)

PMID:34048005 SUPPORT REVIEW SYNTHESIS Model organism

"Among the murine models of intraperitoneal sepsis, cecal ligation and puncture (CLP), is one of the most frequently used and generally accepted as the “gold standard”."

This mouse-model review identifies CLP as a standard model of intraperitoneal sepsis.

+ 1 more reference

{ }

Source YAML

click to show

name: Septic Peritonitis
creation_date: "2026-11-04T00:00:00Z"
description: >-
  Septic peritonitis is an acquired intra-abdominal bacterial infection in
  which a gastrointestinal leak, biliary leak, postoperative dehiscence,
  or traumatic perforation contaminates the peritoneal cavity. Enteric aerobic
  and anaerobic organisms seed the mesothelial surface, activate resident
  sentinel cells, recruit neutrophils, and can progress from purulent local
  peritonitis to abdominal sepsis, septic shock, and multiple organ dysfunction
  unless surgical or percutaneous source control and antimicrobial therapy
  interrupt ongoing contamination.
category: Infectious Disease
disease_term:
  preferred_term: septic peritonitis
  term:
    id: MONDO:0005195
    label: septic peritonitis
parents:
- Infectious peritonitis
- Bacterial infectious disease
synonyms:
- Secondary septic peritonitis
notes: >-
  This entry models bacterial secondary septic peritonitis after hollow-viscus,
  biliary, postoperative, or traumatic contamination of the peritoneum.
  Spontaneous bacterial peritonitis, peritoneal dialysis-associated peritonitis,
  sterile chemical peritonitis, and recurrent tertiary peritonitis after source
  control are outside this entry's scope.
progression:
- phase: Visceral breach and peritoneal contamination
  notes: >-
    Secondary septic peritonitis begins when loss of gastrointestinal integrity
    or another intra-abdominal source exposes the peritoneum to enteric
    organisms and inflammatory luminal contents.
  evidence:
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Secondary (the most common ones): derived from loss of integrity of the
      gastrointestinal tract.
    explanation: >-
      This source-control review distinguishes secondary peritonitis from
      primary and tertiary infectious peritonitis by its origin in a
      gastrointestinal integrity defect.
- phase: Localized or diffuse purulent peritonitis
  notes: >-
    Enteric contamination can remain localized or extend through the peritoneal
    cavity as fibrinous, purulent, or stercoraceous secondary peritonitis.
  evidence:
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Intra-abdominal infections can be categorized as uncomplicated if they
      affect just one organ and do not spread to the peritoneum, or complicated
      if the infection spreads to the peritoneum, causing localized or diffuse
      peritonitis
    explanation: >-
      The review records localized and diffuse peritonitis as the peritoneal
      extension states of complicated intra-abdominal infection.
- phase: Intra-abdominal sepsis and septic shock
  notes: >-
    Ongoing abdominal infection can cross from local purulent inflammation into
    dysregulated systemic inflammation, organ dysfunction, and septic shock.
  evidence:
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Clinical manifestations are widely varied and IAS, especially if poorly
      managed, can cause immune response deregulation leading to septic shock.
    explanation: >-
      The review describes progression from intra-abdominal sepsis toward septic
      shock when the abdominal infection is not adequately managed.
- phase: Source-controlled resolution or persistent infection
  notes: >-
    Successful source control removes the leaking or infected focus; failure to
    eliminate the source can leave persistent abscesses, chronic inflammation,
    or recurrent tertiary peritonitis after apparently adequate surgery.
  evidence:
  - reference: PMID:8891619
    reference_title: Predictors of outcome in patients with postoperative intra-abdominal infection.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      In 37 of the patients the source of infection was eliminated resulting in
      7 deaths (19%); all 11 of those in whom it was not eliminated died.
    explanation: >-
      This postoperative intra-abdominal infection cohort links source
      elimination to survival and identifies failure to eliminate the source as
      a terminally poor-prognosis course.
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Tertiary: recurrent peritoneal infection which occurs more than 48 h after
      apparently successful and adequate surgical source control of secondary
      peritonitis
    explanation: >-
      This review defines tertiary peritonitis as a recurrent outcome after
      attempted source control of secondary peritonitis.
clinical_burden:
  burden_level: HIGH
  rationale: >-
    Complicated intra-abdominal infection that reaches the peritoneal cavity can
    become abdominal sepsis with substantial in-hospital mortality; adequate
    source control is a dominant determinant of survival.
  evidence:
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Intra-abdominal infections (IAIs) account for a major cause of morbidity
      and mortality, representing the second most common sepsis-related death
      with a hospital mortality of 23-38%.
    explanation: >-
      This 2024 review quantifies the clinical burden of intra-abdominal
      infection, the disease class that includes peritoneal spread with
      localized or diffuse peritonitis.
  - reference: PMID:8891619
    reference_title: Predictors of outcome in patients with postoperative intra-abdominal infection.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      In 37 of the patients the source of infection was eliminated resulting in
      7 deaths (19%); all 11 of those in whom it was not eliminated died.
    explanation: >-
      A postoperative intra-abdominal infection cohort links elimination of the
      infectious source to survival, supporting the high burden of disease when
      source control fails.
infectious_agent:
- name: Escherichia coli
  description: >-
    Escherichia coli is an enteric aerobic Gram-negative bacterium recovered in
    polymicrobial purulent secondary peritonitis after gastrointestinal leakage.
  infectious_agent_term:
    preferred_term: Escherichia coli
    term:
      id: NCBITaxon:562
      label: Escherichia coli
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      In intra-abdominal infections, the peritoneal microbiome reflects the
      contaminating intestinal microbiome, with a predominance of enteric
      Gram-Negative bacteria (Escherichia coli, Klebsiella spp., Enterobacter
      spp.), anaerobes (Bacteroides fragilis, Clostridium spp.), and
      Gram-Positive bacteria (Enterococcus spp.).
    explanation: >-
      The secondary-peritonitis review lists E. coli and other aerobic
      Gram-negative taxa among the organisms in purulent secondary peritonitis.
- name: Bacteroides fragilis
  description: >-
    Bacteroides fragilis is an enteric anaerobe that contributes to the
    polymicrobial communities recovered in secondary peritonitis after fecal or
    lower-intestinal contamination.
  infectious_agent_term:
    preferred_term: Bacteroides fragilis
    term:
      id: NCBITaxon:817
      label: Bacteroides fragilis
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      In intra-abdominal infections, the peritoneal microbiome reflects the
      contaminating intestinal microbiome, with a predominance of enteric
      Gram-Negative bacteria (Escherichia coli, Klebsiella spp., Enterobacter
      spp.), anaerobes (Bacteroides fragilis, Clostridium spp.), and
      Gram-Positive bacteria (Enterococcus spp.).
    explanation: >-
      The review identifies B. fragilis among anaerobes recovered from
      intra-abdominal infection.
classifications:
  harrisons_chapter:
  - classification_value: GASTROINTESTINAL
  - classification_value: CRITICAL_CARE
  - classification_value: INFECTIOUS_DISEASES
transmission:
- name: Endogenous peritoneal inoculation
  description: >-
    Septic peritonitis is not spread as a person-to-person syndrome; it usually
    begins when a hollow-viscus leak, surgical dehiscence, biliary leak, or
    other intra-abdominal source inoculates the peritoneal cavity with organisms
    from the patient's own gastrointestinal tract or biliary tract.
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Secondary peritonitis is traditionally defined as inflammation of the
      peritoneal cavity secondary to the loss of integrity of a hollow viscus or
      a chemically irritating leakage of biological fluids onto the peritoneum.
    explanation: >-
      This definition identifies visceral or fluid leakage into the peritoneum
      as the usual initiating exposure for secondary septic peritonitis.
pathophysiology:
- name: Gastrointestinal Barrier Failure
  role: trigger
  biological_scale: TISSUE
  description: >-
    A full-thickness gastrointestinal defect, anastomotic leak, biliary leak,
    or penetrating injury breaches the normally sterile peritoneal compartment
    and delivers bacteria or inflammatory luminal contents onto the peritoneal
    surface.
  locations:
  - preferred_term: peritoneum
    term:
      id: UBERON:0002358
      label: peritoneum
  downstream:
  - target: Polymicrobial Peritoneal Seeding
    causal_link_type: DIRECT
    description: >-
      The barrier breach delivers enteric aerobic and anaerobic organisms into
      peritoneal fluid and onto mesothelial surfaces.
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Secondary peritonitis is traditionally defined as inflammation of the
      peritoneal cavity secondary to the loss of integrity of a hollow viscus or
      a chemically irritating leakage of biological fluids onto the peritoneum.
    explanation: >-
      The review identifies hollow-viscus disruption and leakage of biological
      fluid as sources for secondary peritoneal inflammation and infection.
- name: Polymicrobial Peritoneal Seeding
  biological_scale: TISSUE
  description: >-
    Feculent or purulent contamination introduces mixed aerobic and anaerobic
    communities, including Enterobacterales and Bacteroides, into the
    peritoneal space.
  locations:
  - preferred_term: peritoneal fluid
    term:
      id: UBERON:0001268
      label: peritoneal fluid
  downstream:
  - target: Mesothelial Innate Cytokine Release
    causal_link_type: DIRECT
    description: >-
      Bacterial products contact mesothelial and resident innate immune cells,
      which respond by releasing inflammatory mediators.
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      In peritonitis, the peritoneal cavity hosts diverse, often polymicrobial
      communities, with complex interactions between aerobic and anaerobic
      bacteria, as well as fungi.
    explanation: >-
      The review summarizes the fecal-contamination variant of secondary
      peritonitis as an enteric polymicrobial process.
- name: Mesothelial Innate Cytokine Release
  biological_scale: CELLULAR
  description: >-
    Peritoneal mesothelial cells sense microbial products, release IL-6, IL-8,
    TNF, CXCL1, and CCL2, and start the chemokine gradient that recruits
    neutrophils into the infected peritoneum.
  cell_types:
  - preferred_term: mesothelial cell
    term:
      id: CL:0000077
      label: mesothelial cell
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  downstream:
  - target: Purulent Peritoneal Inflammation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - IL-8 and CXCL1 chemokine gradients
    description: >-
      Mesothelial cytokine and chemokine release promotes recruitment of
      neutrophils into the peritoneal cavity.
  - target: Abdominal Sepsis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Local cytokine spillover
    - Organ dysfunction
    description: >-
      Peritoneal innate immune activation can spread systemically as a
      dysregulated host response with organ dysfunction.
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Mesothelial cells are front-line sentinels releasing IL-6, IL-8, tumor
      necrosis factor (TNF)-α, CXCL1 and CCL2 after exposure to microbial
      products
    explanation: >-
      The review directly connects microbial exposure at the peritoneum with
      mesothelial release of neutrophil-recruiting and proinflammatory
      mediators.
- name: Purulent Peritoneal Inflammation
  biological_scale: TISSUE
  description: >-
    Bowel-content contamination generates purulent peritoneal inflammation that
    produces local acute-abdomen signs and can progress systemically when source
    control and antimicrobial therapy do not interrupt it.
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  downstream:
  - target: Fibrinous Loculation and Abscess Formation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Coagulation-fibrinolysis imbalance
    description: >-
      Peritonitis favors peritoneal coagulation and impaired fibrin clearance,
      promoting loculated abscess formation.
    evidence:
    - reference: PMID:12734857
      reference_title: Pathophysiology of intra-abdominal adhesion and abscess formation, and the effect of hyaluronan.
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: >-
        Both surgery and peritonitis disturb the equilibrium between coagulation
        and fibrinolysis in the abdominal cavity in favour of the coagulation
        system.
      explanation: >-
        This review identifies peritonitis-driven coagulation bias as an
        intermediate between abdominal inflammation and later fibrinous
        loculation.
  - target: Abdominal Sepsis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Uncontrolled local bacterial infection can spread into a systemic septic
      host response.
    evidence:
    - reference: PMID:39200076
      reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: >-
        Clinical manifestations are widely varied and IAS, especially if poorly
        managed, can cause immune response deregulation leading to septic shock.
      explanation: >-
        This source-control review connects poorly controlled intra-abdominal
        sepsis to systemic immune dysregulation and septic shock.
  - target: Abdominal pain
    causal_link_type: DIRECT
    description: >-
      Peritoneal irritation produces the abdominal pain and tenderness of an
      acute abdomen.
  - target: Hypoactive bowel sounds
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Ileus
    description: >-
      Purulent peritoneal inflammation impairs bowel motility and produces
      diminished or absent bowel sounds.
  - target: Abdominal guarding
    causal_link_type: DIRECT
    description: >-
      Peritoneal inflammation irritates the abdominal cavity and produces local
      guarding or rigidity.
  - target: Abdominal distention
    causal_link_type: DIRECT
    description: >-
      Peritoneal inflammation produces distention and diminished bowel sounds as
      acute-abdomen manifestations.
  - target: Fever
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Systemic inflammatory response
    description: >-
      Local peritoneal infection drives systemic inflammatory signs including
      fever.
  - target: Tachycardia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Systemic inflammatory response
    description: >-
      Local peritoneal infection can progress to systemic inflammation with
      tachycardia.
  - target: Dehydration
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Third spacing and systemic inflammatory response
    description: >-
      Acute perforation peritonitis can present with dehydration during the
      systemic inflammatory acute-abdomen syndrome.
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      This section groups the condition into five archetypal variants, namely
      fibrinous mainly related to peptic ulcer perforation (PUP), purulent
      either due to colonic or non-colonic perforation
    explanation: >-
      This review places purulent secondary peritonitis within the diffuse
      forms produced by visceral-barrier breach.
- name: Fibrinous Loculation and Abscess Formation
  biological_scale: TISSUE
  description: >-
    The inflamed abdominal cavity develops impaired fibrin degradation, walling
    off infection into adhesions and abscesses but also creating protected
    infectious foci.
  locations:
  - preferred_term: peritoneum
    term:
      id: UBERON:0002358
      label: peritoneum
  evidence:
  - reference: PMID:12734857
    reference_title: Pathophysiology of intra-abdominal adhesion and abscess formation, and the effect of hyaluronan.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Diminished fibrin degradation is a common pathway for the formation of
      adhesions and abscesses.
    explanation: >-
      This review connects impaired abdominal fibrin degradation to the adhesion
      and abscess formation that creates loculated infectious foci during
      peritonitis.
- name: Abdominal Sepsis
  biological_scale: ORGANISM
  description: >-
    Failure to control the intra-abdominal source allows inflammatory mediator
    spillover and bacterial products to drive life-threatening organ dysfunction
    as abdominal sepsis.
  downstream:
  - target: Sepsis
    causal_link_type: DIRECT
    description: >-
      Intra-abdominal infection can drive the dysregulated systemic host
      response and organ dysfunction that define sepsis.
  - target: Shock
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Immune-response dysregulation
    - Hemodynamic collapse
    description: >-
      Severe intra-abdominal sepsis can progress to septic shock.
    evidence:
    - reference: PMID:39200076
      reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      snippet: >-
        Clinical manifestations are widely varied and IAS, especially if poorly
        managed, can cause immune response deregulation leading to septic shock.
      explanation: >-
        This review connects intra-abdominal sepsis to downstream septic shock.
  evidence:
  - reference: PMID:30685836
    reference_title: "Intra-abdominal sepsis: new definitions and current clinical standards."
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Sepsis-3 defines sepsis as a life-threatening organ dysfunction caused by
      a dysregulated host response to infection.
    explanation: >-
      This review applies the Sepsis-3 organ-dysfunction definition to
      intra-abdominal infection.
phenotypes:
- name: Sepsis
  description: >-
    Septic peritonitis can progress from a local peritoneal infection to
    abdominal sepsis with life-threatening organ dysfunction.
  phenotype_term:
    preferred_term: Sepsis
    term:
      id: HP:0100806
      label: Sepsis
  evidence:
  - reference: PMID:30685836
    reference_title: "Intra-abdominal sepsis: new definitions and current clinical standards."
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The abdomen is the second most common source of sepsis and is associated
      with unacceptably high morbidity and mortality.
    explanation: >-
      Identifies the abdomen as a major sepsis source, supporting sepsis as a
      key systemic manifestation of septic peritonitis and other abdominal
      infections.
- name: Abdominal pain
  description: >-
    Peritoneal irritation presents as acute abdominal pain or tenderness in
    perforation peritonitis.
  phenotype_term:
    preferred_term: Abdominal pain
    term:
      id: HP:0002027
      label: Abdominal pain
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: >-
      Peritonitis usually presents as an acute abdomen. Local findings include
      abdominal tenderness, guarding or rigidity, distension, diminished bowel
      sounds.
    explanation: >-
      The cohort-study introduction lists abdominal tenderness among the local
      acute-abdomen signs of peritonitis.
- name: Hypoactive bowel sounds
  description: >-
    Perforation peritonitis commonly diminishes or abolishes bowel sounds as a
    manifestation of peritoneal inflammation and ileus.
  phenotype_term:
    preferred_term: Hypoactive bowel sounds
    term:
      id: HP:0030144
      label: Hypoactive bowel sounds
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      diminished or absent bowel sound (57.14%), shock (54.29%). tachycardia
      (54.28%), dehydration (52.85%)
    explanation: >-
      This 490-patient perforation-peritonitis cohort reported diminished or
      absent bowel sounds in more than half of patients.
- name: Abdominal guarding
  description: >-
    Purulent peritoneal irritation commonly produces abdominal guarding or
    rigidity, a local acute-abdomen sign.
  phenotype_term:
    preferred_term: Abdominal guarding
    term:
      id: HP:0032546
      label: Abdominal guarding
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      Abdominal guarding was present in 97.14% patients followed by diminished
      or absent bowel sound (57.14%), shock (54.29%).
    explanation: >-
      This 490-patient perforation-peritonitis cohort reported abdominal
      guarding in nearly all cases.
- name: Abdominal distention
  description: >-
    Perforation peritonitis can present with abdominal distention as a local
    manifestation of peritoneal inflammation and ileus.
  phenotype_term:
    preferred_term: Abdominal distention
    term:
      id: HP:0003270
      label: Abdominal distention
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: >-
      Local findings include abdominal tenderness, guarding or rigidity,
      distension, diminished bowel sounds.
    explanation: >-
      This cohort-study introduction lists abdominal distension among local
      findings in perforation peritonitis.
- name: Shock
  description: >-
    Severe septic peritonitis can progress from a local peritoneal infection to
    hemodynamic shock.
  phenotype_term:
    preferred_term: Shock
    term:
      id: HP:0031273
      label: Shock
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      Abdominal guarding was present in 97.14% patients followed by diminished
      or absent bowel sound (57.14%), shock (54.29%).
    explanation: >-
      This 490-patient perforation-peritonitis cohort reported shock in more
      than half of patients.
- name: Fever
  description: >-
    Fever is a common systemic manifestation of perforation peritonitis and the
    inflammatory response to intra-abdominal infection.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: >-
      Systemic findings include fever, chills or rigor, tachycardia, sweating,
      tachypnea, restlessness, dehydration, oliguria, disorientation and
      ultimately shock
    explanation: >-
      The cohort-study introduction lists fever among the systemic findings in
      perforation peritonitis.
- name: Tachycardia
  description: >-
    Perforation peritonitis commonly produces tachycardia during the systemic
    inflammatory acute-abdomen presentation.
  phenotype_term:
    preferred_term: Tachycardia
    term:
      id: HP:0001649
      label: Tachycardia
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      diminished or absent bowel sound (57.14%), shock (54.29%). tachycardia
      (54.28%), dehydration (52.85%)
    explanation: >-
      This 490-patient perforation-peritonitis cohort reported tachycardia in
      more than half of patients.
- name: Dehydration
  description: >-
    Perforation peritonitis can present with dehydration during the systemic
    inflammatory acute-abdomen syndrome.
  phenotype_term:
    preferred_term: Dehydration
    term:
      id: HP:0001944
      label: Dehydration
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      diminished or absent bowel sound (57.14%), shock (54.29%). tachycardia
      (54.28%), dehydration (52.85%)
    explanation: >-
      This 490-patient perforation-peritonitis cohort reported dehydration in
      more than half of patients.
biochemical:
- name: Procalcitonin
  notes: >-
    Procalcitonin is a circulating inflammatory biomarker used with other
    markers for secondary-peritonitis diagnosis, prognostication, and monitoring.
  biomarker_term:
    preferred_term: Procalcitonin
    term:
      id: NCIT:C173465
      label: Procalcitonin
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Biomarkers such as procalcitonin (PCT), interleukin-6 (IL-6), high
      mobility group box 1 (HMGB1), C-reactive protein (CRP),
      lipopolysaccharide (LPS), neutrophil-to-lymphocyte ratio (NLR), and
      neutrophil gelatinase-associated lipocalin (NGAL) have emerged as tools
      for early diagnosis, subtype stratification, and monitoring of therapeutic
      response.
    explanation: >-
      The review identifies procalcitonin among the secondary-peritonitis
      biomarkers with diagnostic, stratification, and treatment-monitoring use.
- name: C-reactive protein
  notes: >-
    C-reactive protein is a circulating inflammatory biomarker used with other
    markers to support secondary-peritonitis diagnosis and monitoring.
  biomarker_term:
    preferred_term: C-Reactive Protein
    term:
      id: NCIT:C60651
      label: C-Reactive Protein
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Biomarkers such as procalcitonin (PCT), interleukin-6 (IL-6), high
      mobility group box 1 (HMGB1), C-reactive protein (CRP),
      lipopolysaccharide (LPS), neutrophil-to-lymphocyte ratio (NLR), and
      neutrophil gelatinase-associated lipocalin (NGAL) have emerged as tools
      for early diagnosis, subtype stratification, and monitoring of therapeutic
      response.
    explanation: >-
      The review identifies CRP among secondary-peritonitis biomarkers used for
      diagnosis, subtype stratification, and response monitoring.
diagnosis:
- name: Clinical and plain-film acute-abdomen assessment
  description: >-
    Perforation peritonitis is initially assessed from the acute history,
    physical examination, and erect abdominal X-ray evidence of
    pneumoperitoneum while the team triages the perforated or infected source.
  evidence:
  - reference: PMID:24392388
    reference_title: Spectrum of perforation peritonitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      Initial diagnosis was made on the basis of detailed history, clinical
      examination and presence of pneumoperitoneum on erect abdominal X-ray.
    explanation: >-
      A 490-patient perforation-peritonitis cohort documents an initial
      diagnostic assessment combining history, examination, and erect abdominal
      radiography for pneumoperitoneum.
- name: Abdominal CT source localization
  description: >-
    Abdominal CT is used in the emergency workup to help diagnose severe
    intra-abdominal sepsis and localize the perforated or infected source for
    source-control planning.
  diagnosis_term:
    preferred_term: Computed Tomography
    term:
      id: NCIT:C17204
      label: Computed Tomography
  evidence:
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      A prompt diagnosis of severe IAS often requires an adequate clinical
      evaluation, laboratory tests, and imaging exams, such as abdominal
      ultrasound or Computed Tomography (CT), which are among the most used
      diagnostic procedures in emergency settings
    explanation: >-
      This source-control review identifies CT and ultrasound among emergency
      diagnostic procedures for severe intra-abdominal sepsis.
treatments:
- name: Surgical Source Control
  description: >-
    Surgical or percutaneous source control reduces microbial burden by
    repairing, resecting, draining, debriding, decompressing, or removing the
    anatomic source of peritoneal contamination.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Surgical source control
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Gastrointestinal Barrier Failure
    treatment_effect: INHIBITS
    description: >-
      Source control closes or removes the leak that continues to seed the
      peritoneum.
  - target: Fibrinous Loculation and Abscess Formation
    treatment_effect: INHIBITS
    description: >-
      Drainage and debridement evacuate infected loculated collections and
      remove necrotic foci that preserve bacterial burden.
  evidence:
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The aim of source control is to reduce microbial load by removing the
      infection source and it is achievable by using a wide range of procedures,
      such as definitive surgical removal of anatomic infectious foci,
      percutaneous drainage and toilette of infected collections,
      decompression, and debridement of infected and necrotic tissue or device
      removal
    explanation: >-
      Defines source control across surgical removal, drainage, decompression,
      debridement, and device removal for intra-abdominal infection.
- name: Broad-Spectrum Antimicrobial Therapy
  description: >-
    Antimicrobial therapy suppresses enteric Gram-negative and anaerobic
    organisms seeded into the peritoneal cavity; regimen choice is guided by
    clinical status, local resistance epidemiology, and risks for
    multidrug-resistant bacteria or Candida.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Antibiotic Therapy
    term:
      id: NCIT:C15620
      label: Antibiotic Therapy
  target_mechanisms:
  - target: Polymicrobial Peritoneal Seeding
    treatment_effect: INHIBITS
    description: >-
      Antimicrobial therapy inhibits or kills the organisms seeded into the
      peritoneal cavity while surgical source control removes the source.
  evidence:
  - reference: PMID:41227298
    reference_title: A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      The treatment of secondary peritonitis relies on two fundamental
      principles: rapid surgical source control even with intraperitoneal
      negative-pressure therapy and effective antimicrobial therapy
    explanation: >-
      Summarizes antimicrobial therapy as one of the two fundamental treatment
      principles for secondary peritonitis.
  - reference: PMID:27670577
    reference_title: Patients with Risk Factors for Complications Do Not Require Longer Antimicrobial Therapy for Complicated Intra-Abdominal Infection.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    snippet: >-
      A short course of antibiotics in complicated intra-abdominal infection
      with source control seems to have similar outcomes to a longer course in
      patients with diabetes, obesity, or increased severity of illness.
    explanation: >-
      A STOP-IT trial subgroup analysis supports limiting antibiotic duration
      after source control, including in high-risk complicated
      intra-abdominal infection.
  - reference: PMID:39200076
    reference_title: Source Control and Antibiotics in Intra-Abdominal Infections.
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    snippet: >-
      Antibiotic and antifungal regimens in patients with IAIs should be based
      on the resistance epidemiology, clinical conditions, and risk for
      multidrug resistance (MDR) and Candida spp. infections.
    explanation: >-
      Supports selecting antimicrobial regimens by resistance epidemiology,
      clinical status, and multidrug-resistance or Candida risk.
animal_models:
- name: Cecal ligation and puncture mouse
  species: Mouse
  description: >-
    Cecal ligation and puncture is a standard adult mouse model of
    polymicrobial intraperitoneal sepsis induced by surgical cecal injury, but
    the devitalized cecum leaves an uncorrected source that prevents the model
    from representing source-controlled clinical resolution.
  publication: PMID:34048005
  modeled_mechanisms:
  - target: Polymicrobial Peritoneal Seeding
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: >-
      CLP seeds cecal contents into the mouse peritoneum and produces
      polymicrobial intraperitoneal sepsis.
    limitations: >-
      The devitalized cecum remains in place, so CLP does not model an episode
      where surgical source control closes or removes the leaking focus.
    divergences:
    - divergence_type: BOUNDARY_OMISSION
      materiality: QUALIFYING
      description: >-
        Definitive source control is outside the CLP model boundary even though
        source repair or removal is central to the human secondary-peritonitis
        course and treatment strategy curated here.
    evidence:
    - reference: PMID:34048005
      reference_title: Cecal Slurry Injection in Neonatal and Adult Mice.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: REVIEW_SYNTHESIS
      snippet: >-
        Among the murine models of intraperitoneal sepsis, cecal ligation and
        puncture (CLP), is one of the most frequently used and generally
        accepted as the “gold standard”.
      explanation: >-
        This mouse-model review identifies CLP as a standard model of
        intraperitoneal sepsis.
    - reference: PMID:34048005
      reference_title: Cecal Slurry Injection in Neonatal and Adult Mice.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      quote_role: REVIEW_SYNTHESIS
      snippet: >-
        Despite antibiotic treatment, the presence of a devitalized cecum
        assures failure of any antibiotic intervention to completely resolve the
        infection, and involves both abscess formation and chronic
        inflammation.
      explanation: >-
        The same model review explains that the ligated cecum leaves a
        devitalized infectious focus that prevents complete antimicrobial
        resolution.

📚

References & Deep Research

Deep Research

1

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Septic Peritonitis (MONDO:0005195): A Comprehensive Disease Characterization Report

openscientist-autonomous 39 citations 2026-09-30T03:51:08.519339

Septic Peritonitis (MONDO:0005195): A Comprehensive Disease Characterization Report

Summary

Septic peritonitis is a life-threatening bacterial infection of the peritoneal cavity, most commonly arising as secondary peritonitis from disruption of the gastrointestinal tract (perforation, ischemia, dehiscence, or penetrating trauma). Contamination of the normally sterile peritoneum with polymicrobial gut flora triggers a dysregulated innate-immune response—pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) activating resident peritoneal macrophages and mesothelium via Toll-like receptor/NF-κB signaling, releasing a cytokine cascade (TNF-α, IL-1β, IL-6, HMGB1) with massive neutrophil recruitment. When this response becomes systemic and dysregulated, it produces sepsis—defined by Sepsis-3 as "life-threatening organ dysfunction caused by a dysregulated host response to infection"—and can progress to septic shock and multiple organ dysfunction syndrome (MODS). The abdomen is the second most common source of sepsis, and intra-abdominal infections carry hospital mortality of 23–38%, rising above 80% in severe complicated intra-abdominal sepsis (SCIAS).

This report is derived from aggregated disease-level resources (clinical guidelines, cohort studies, systematic reviews, and experimental model literature)—not individual patient EHR records. Importantly, septic peritonitis is an infectious/mechanical disease, not a Mendelian genetic disorder: it has no causal gene, no inheritance pattern, no pathogenic variant class, and no vaccine. Genetic contributions are limited to polygenic host-susceptibility modifiers of the sepsis response. Consequently, several sections of the standard disease template (causal genes, pathogenic variants, chromosomal abnormalities, repeat-expansion testing, genetic counseling) are not applicable and are marked as such.

The two therapeutic pillars are source control (surgical debridement, drainage, removal of infected devices, decompression) and early broad-spectrum empiric antibiotics with resuscitation. Source control is the dominant determinant of survival: in postoperative intra-abdominal infection, eliminating the infection source reduced mortality from 100% to 19%. The landmark STOP-IT trial showed that ~4 days of antibiotics suffice after adequate source control. Septic peritonitis is also a common, high-mortality naturally occurring disease in dogs and cats (overall mortality ~64% in GI-perforation cases), where it is elegantly diagnosed by a blood-to-peritoneal-fluid glucose difference >20 mg/dL (100% sensitive/specific in dogs). The gold-standard experimental model is cecal ligation and puncture (CLP) in mice.

1. Disease Information

Overview. Septic peritonitis is inflammation of the peritoneum (the serous membrane lining the abdominal cavity and viscera) caused by bacterial infection, most often following breach of a hollow viscus. It is a form of intra-abdominal infection (IAI) and, when the host response becomes dysregulated, of abdominal sepsis. Intra-abdominal infections "account for a major cause of morbidity and mortality, representing the second most common sepsis-related death with a hospital mortality of 23-38%" (PMID: 39200076).

Key identifiers. - MONDO: MONDO:0005195 - MeSH: Peritonitis (D010538) - ICD-10: K65 (Peritonitis); K65.0 (Generalized/acute peritonitis); K65.1 (Peritoneal abscess); K65.9 (Peritonitis, unspecified) - ICD-11: DC50 (Peritonitis) - SNOMED CT: 48661000 (Peritonitis); 65119005 (Bacterial peritonitis) - OMIM / Orphanet: Not applicable — septic peritonitis is an acquired infectious/surgical condition, not a Mendelian or rare genetic disease, so it has no OMIM phenotype number and no Orphanet ORPHA code.

Synonyms / alternative names. Bacterial peritonitis; suppurative peritonitis; secondary peritonitis (most relevant subtype); acute bacterial peritonitis; purulent peritonitis; abdominal sepsis / intra-abdominal sepsis (when systemic); surgical peritonitis. Related but distinct: spontaneous bacterial peritonitis (SBP, the primary form), tertiary peritonitis.

Source of information. Aggregated disease-level resources — clinical guidelines (WSES, Surviving Sepsis), retrospective and prospective cohort studies, systematic reviews, and experimental animal-model literature.

2. Etiology

Primary causal factors — infectious and mechanical. The proximate cause is microbial contamination of the sterile peritoneal cavity, overwhelmingly from a breach of the gastrointestinal tract. "Secondary peritonitis is a life-threatening intra-abdominal condition arising from gastrointestinal perforation, chemical injury, or catheter-related infections" (PMID: 41227298). Common precipitating lesions include perforated peptic ulcer, perforated appendicitis, perforated diverticulitis, bowel ischemia/necrosis, anastomotic dehiscence after GI surgery, penetrating/blunt abdominal trauma, and perforated malignancy. The infection is typically polymicrobial, reflecting gut flora (Escherichia coli and other Enterobacterales, Bacteroides fragilis and anaerobes, enterococci; Candida in upper-GI perforation).

Genetic risk factors. There are no causal Mendelian variants or established susceptibility loci specific to septic peritonitis. As an acquired infection, risk is governed by the anatomical lesion and by polygenic host modifiers of the innate-immune/sepsis response (e.g., variants in TLR4, TNF, IL-6 pathways have been studied in sepsis generally, but none are diagnostic or actionable for peritonitis). This section is largely not applicable.

Environmental / clinical risk factors. - Medications: Non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids promote GI ulceration/perforation. In companion animals, "administration of anti-inflammatory drugs in dogs and cats is a significant risk factor for pyloric perforation" (PMID: 24283417). - Comorbidities: diabetes mellitus, immunosuppression, malignancy, diverticular disease, peptic ulcer disease, cirrhosis (predisposes to the primary/SBP form). - Procedural: recent abdominal surgery, peritoneal dialysis catheters, foreign-body migration (e.g., grass awns in animals; PMID: 36874536). - Demographic: advancing age (higher perforation and mortality risk).

Protective factors. No genetic protective variants are established. Protective/beneficial factors are effectively preventive and therapeutic: prompt surgical source control, early appropriate antibiotics, and management of predisposing GI disease. There is no dietary or vaccine-based primary prevention.

Gene–environment interactions. Not established as clinically meaningful. Host genetic modulation of the cytokine response may interact with pathogen burden to influence sepsis severity, but this is speculative for peritonitis specifically and not actionable.

3. Phenotypes

Septic peritonitis presents acutely with a constellation of peritoneal signs and systemic sepsis features. In a comparative study of acute abdomen, "common signs were tenderness, rebound tenderness, guarding/rigidity, tachycardia, and abdominal distention" (PMID: 42583660).

Phenotype	Type	HPO suggestion	Frequency/severity	Onset/progression
Abdominal pain	Symptom	HP:0002027 (Abdominal pain)	Near-universal; severe	Acute; progressive
Rebound tenderness / peritoneal signs	Clinical sign	HP:0002027	Very common	Acute
Abdominal guarding/rigidity	Clinical sign	HP:0025380 (Abdominal guarding)	Common	Acute
Fever	Sign	HP:0001945 (Fever)	Common	Acute; may be absent/hypothermia in severe sepsis
Nausea and vomiting	Symptom	HP:0002018 / HP:0002013	Common	Acute
Anorexia	Symptom	HP:0002039 (Anorexia)	Common	Acute
Tachycardia	Sign	HP:0001649 (Tachycardia)	Common	Acute
Abdominal distension	Sign	HP:0003270 (Abdominal distention)	Common	Acute/subacute
Hypotension / septic shock	Sign	HP:0002615 (Hypotension)	In severe disease	Acute; life-threatening
Leukocytosis (or leukopenia)	Lab abnormality	HP:0001974 / HP:0001882	Common	Acute
Elevated CRP / procalcitonin	Lab abnormality	HP:0011227 (Elevated CRP)	Common	Acute
Lactic acidosis	Lab abnormality	HP:0003128 (Lactic acidosis)	Severe disease; prognostic	Acute
Multi-organ dysfunction	Complication	HP:0011024 (GI), HP:0000083 (Renal insufficiency)	Severe/tertiary	Progressive

Age of onset. Any age; predominantly adult and geriatric (matching perforation risk). Neonatal forms occur secondary to necrotizing enterocolitis-associated intestinal perforation.

Severity/progression. Acute onset, rapidly progressive; if untreated, escalates to septic shock and MODS within hours to days. Quality-of-life impact in the acute phase is severe (ICU-level illness); survivors of abdominal sepsis may experience prolonged recovery, post-intensive-care syndrome, and long hospital stays. Disease-specific QoL instruments are not standard; generic ICU/sepsis outcome measures apply.

4. Genetic/Molecular Information

This section is largely NOT APPLICABLE. Septic peritonitis is an acquired infectious disease with: - No causal genes (no OMIM gene entries). - No pathogenic variants (no ClinVar classifications, no ACMG/AMP-relevant germline or somatic variants, no allele-frequency considerations). - No chromosomal abnormalities. - No disease-specific epigenetic signature established as diagnostic.

Modifier genes (host susceptibility, research-level only). Polygenic variation in innate-immune signaling (TLR4/CD14/LBP–LPS recognition, TNF, IL6, IL1B, NLR-family inflammasome genes) modulates the intensity of the sepsis response but is neither diagnostic nor actionable. Experimental work implicates inflammasome and receptor genes in host defense—e.g., NLRC4 deficiency improved survival and bacterial clearance in CLP-induced polymicrobial sepsis (PMID: 41071588), and CD300ld modulates neutrophil bacterial phagocytosis (PMID: 40376837)—but these are mechanistic/model findings, not human germline disease genes.

5. Environmental Information

Environmental / iatrogenic factors. NSAIDs and corticosteroids (GI ulceration), abdominal surgery, peritoneal dialysis catheters, and intra-abdominal foreign bodies. No environmental toxin, radiation, or pollutant is a recognized cause.

Lifestyle factors. Alcohol use (pancreatitis, cirrhosis/SBP risk), smoking (peptic ulcer disease). Diet-related diverticular disease contributes to perforated diverticulitis.

Infectious agents (the direct cause of secondary septic peritonitis). Typically polymicrobial enteric flora: - Gram-negative bacteria (NCBI Taxonomy): Escherichia coli (NCBI:txid562) — most common; Klebsiella, Enterobacter, Proteus, Pseudomonas aeruginosa. - Anaerobes: Bacteroides fragilis, Clostridium spp. - Gram-positive: Enterococcus spp., streptococci, Staphylococcus aureus (esp. PD-associated). - Fungi: Candida spp., particularly in upper-GI (gastric/duodenal) perforation and tertiary peritonitis.

In companion-animal septic peritonitis, microbial growth occurred in the large majority of peritoneal cultures, with agents effectively covered by cefotaxime, ceftazidime, and imipenem (PMID: 30040445).

6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation)

A GI-tract lesion (perforated ulcer, ruptured appendix/diverticulum, ischemic/necrotic bowel, anastomotic dehiscence, penetrating trauma) leads to spillage of luminal contents and gut flora into the sterile peritoneal cavity. (demonstrated)
Bacterial contamination + PAMPs (e.g., LPS) results in recognition by resident peritoneal macrophages and mesothelial cells via pattern-recognition receptors (TLR4/CD14) → NF-κB activation. (inferred from sepsis biology; supported by biomarker data)
NF-κB activation leads to release of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and alarmins (HMGB1) and chemokines, causing massive neutrophil recruitment into the peritoneum. (supported — biomarkers PCT, IL-6, HMGB1, CRP, LPS, NLR, NGAL elevated; PMID: 41227298)
Branch A (local): Inflammation shifts the peritoneal coagulation–fibrinolysis balance toward coagulation; "both surgery and peritonitis disturb the equilibrium between coagulation and fibrinolysis in the abdominal cavity in favour of the coagulation system," and "diminished fibrin degradation is a common pathway for the formation of adhesions and abscesses" (PMID: 12734857). This results in fibrin deposition, loculation, abscess and adhesion formation — walling off infection but also creating protected bacterial niches. (demonstrated)
Branch B (systemic): Unchecked, cytokines spill into the circulation, causing a dysregulated systemic host response = sepsis ("life-threatening organ dysfunction caused by a dysregulated host response to infection"; PMID: 30685836). (demonstrated)
Systemic inflammation leads to vasodilation, capillary leak, microvascular thrombosis, and hypoperfusion → septic shock and tissue ischemia/oxidative injury. (inferred/demonstrated in sepsis)
Hypoperfusion + direct cytokine injury result in multiple organ dysfunction syndrome (MODS) — acute kidney injury, ARDS, septic cardiomyopathy, hepatic dysfunction, DIC. Septic cardiomyopathy is a documented complication of small-intestinal perforation with peritonitis (PMID: 42260799). (demonstrated)
Immune trajectory: After the hyperinflammatory phase, "most patients survive the hyperinflammatory phase but progress to an immunosuppressive phase, which increases the emergence of secondary infections" (PMID: 31259890), leading to tertiary peritonitis and late mortality. (demonstrated)
Endpoint: death from refractory shock, MODS, or secondary infection unless the causal chain is interrupted by source control + antibiotics. "Mortality typically results from disruption of the gastrointestinal tract, progressive and self-perpetuating bio-mediator generation, systemic inflammation, and multiple organ failure" (PMID: 37170123). (demonstrated)

Category detail

Molecular pathways: TLR4/CD14–LPS → MyD88 → NF-κB; downstream MAPK signaling; inflammasome (NLRC4, NLRP3) → caspase-1 → IL-1β/IL-18 maturation. TNF can switch homeostatic efferocytosis to lytic caspase-8–dependent pyroptosis with IL-1β maturation (PMID: 40540586).
Cellular processes: acute inflammation, phagocytosis, neutrophil extracellular trap formation, pyroptosis/apoptosis, efferocytosis, later immunosuppression.
Immune involvement: central — innate immunity (macrophages, neutrophils, mesothelium) drives both protection and pathology; adaptive dysfunction (T-cell exhaustion, B-1a cell depletion via neutrophil trogocytosis; PMID: 40568588) characterizes the immunosuppressive phase.
Tissue damage mechanisms: oxidative stress, ischemia/hypoperfusion, microvascular thrombosis, fibrin-driven abscess/adhesion, necrosis.
GO term suggestions: GO:0006954 (inflammatory response), GO:0032496 (response to lipopolysaccharide), GO:0007249 (NF-κB signaling), GO:0006909 (phagocytosis), GO:0070269 (pyroptosis), GO:0007596 (blood coagulation), GO:0042060 (wound healing/adhesion).
CL term suggestions: CL:0000864 (tissue-resident macrophage), CL:0000775 (neutrophil), CL:0000077 (mesothelial cell), CL:0000771 (B-1a cell), CL:0000084 (T cell).

7. Anatomical Structures Affected

Organ level. - Primary: peritoneum (UBERON:0002358, parietal peritoneum; UBERON:0002357, serosa) and the perforated hollow viscus (stomach UBERON:0000945, small intestine UBERON:0002108, large intestine/colon UBERON:0001155, appendix UBERON:0001154). - Secondary (complications): kidney (UBERON:0002113, AKI), lung (UBERON:0002048, ARDS), heart (UBERON:0000948, septic cardiomyopathy), liver (UBERON:0002107), spleen (UBERON:0002106), systemic vasculature. - Body systems: digestive (primary), immune/hematologic, cardiovascular, respiratory, renal/urinary — reflecting multi-system sepsis.

Tissue and cell level. Mesothelial lining (epithelial-like serosa), submesothelial connective tissue and vasculature; infiltrating neutrophils (CL:0000775) and peritoneal macrophages (CL:0000864); B-1a cells (CL:0000771) in serosal cavities.

Subcellular level. Mitochondrial dysfunction (bioenergetic failure in sepsis; GO:0005739), nucleus (NF-κB translocation; GO:0005634), inflammasome assembly in cytosol (GO:0005829), plasma-membrane receptor complexes (TLR4; GO:0005886).

Localization / lateralization. Peritonitis is typically diffuse/generalized (bilateral, non-lateralized) when spillage is widespread, or localized (e.g., abscess) when contained. Free intra-abdominal air and diffuse fluid indicate generalized perforation peritonitis.

8. Temporal Development

Onset: acute or subacute (hours to a few days). Insidious onset can occur in immunosuppressed or postoperative patients.
Stages: (1) contamination/local peritonitis → (2) systemic inflammatory/hyperinflammatory sepsis → (3) septic shock/MODS → (4) either resolution (with treatment) or immunosuppressive/tertiary phase with secondary infection.
Progression rate: rapid; can be fulminant, particularly with delayed source control.
Course pattern: acute, potentially self-limited only with definitive intervention; otherwise progressive and fatal.
Remission: treatment-induced (source control + antibiotics); no spontaneous remission for established secondary septic peritonitis.
Critical periods: the early window for source control and antibiotics is decisive — delay markedly worsens outcome; the transition from hyperinflammatory to immunosuppressive phase is a second window of vulnerability to secondary infection.

9. Inheritance and Population

Epidemiology. Septic peritonitis/abdominal sepsis is common and globally important. The abdomen is the second most common source of sepsis (PMID: 30685836), and sepsis overall is a leading cause of death: GBD 2017 estimated ~48.9 million incident sepsis cases and 11 million sepsis-related deaths worldwide, "a major cause of health loss" (PMID: 31954465). IAIs carry hospital mortality of 23–38% (PMID: 39200076), and SCIAS mortality can exceed 80% (PMID: 37170123).

Genetic etiology — NOT APPLICABLE. No inheritance pattern, penetrance, expressivity, anticipation, mosaicism, founder effect, consanguinity role, or carrier frequency. Septic peritonitis is acquired.

Population demographics. Risk rises with age and with predisposing GI disease. No strong ethnic predisposition to the infection itself (although access to timely surgery/critical care strongly affects outcomes and drives geographic mortality variation). Sex distribution roughly reflects the underlying etiology (e.g., perforated ulcer, diverticulitis, appendicitis). Geographic variation in outcome is driven by healthcare access rather than by genetic epidemiology.

10. Diagnostics

Clinical examination. Acute abdomen with tenderness, rebound tenderness, guarding/rigidity, distension, tachycardia, and often fever (PMID: 42583660).

Laboratory tests / biomarkers. Leukocytosis or leukopenia, elevated CRP and procalcitonin (PCT), IL-6, HMGB1, LPS, elevated neutrophil-to-lymphocyte ratio (NLR), NGAL, and lactate. "Biomarkers such as procalcitonin (PCT), interleukin-6 (IL-6), high mobility group box 1 (HMGB1), C-reactive protein (CRP), lipopolysaccharide (LPS), neutrophil-to-lymphocyte ratio (NLR), and neutrophil gelatinase-associated lipocalin (NGAL) have emerged as tools for early diagnosis, subtype stratification, and monitoring of therapeutic response" (PMID: 41227298). LOINC-codable: WBC, CRP, PCT, lactate.

Imaging. CT is the imaging modality of choice — more sensitive than plain radiography for pneumoperitoneum. "Free intra-abdominal air in combination with diffuse fluid is a reliable indication for surgery as it is strongly associated with perforated diverticulitis with generalized peritonitis" (PMID: 22752330). In gastroduodenal perforation, free intraperitoneal air is a direct sign (PMID: 15093233); CT is more sensitive than plain films for detecting free air even in peritoneal-dialysis patients (PMID: 8188913).

Peritoneal fluid analysis (diagnostic cornerstone). Neutrophilic exudate; cytologic identification of intracellular bacteria is confirmatory. In veterinary medicine, a blood-to-fluid glucose difference >20 mg/dL was 100% sensitive and 100% specific for septic peritoneal effusion in dogs, and a blood-to-fluid lactate difference < −2.0 mmol/L was also 100% sensitive/specific (PMID: 12692761). Point-of-care peritoneal culture has ~80% sensitivity/100% specificity (PMID: 34331824). For the primary (SBP) form, diagnosis is an ascitic-fluid neutrophil count >250 cells/mm³ (PMID: 42488876, PMID: 42565189).

Genetic / omics diagnostics — NOT APPLICABLE for diagnosis of the infection (no WGS/WES/panel/karyotype/FISH/mtDNA/repeat-expansion role). Microbiologic culture and, increasingly, metagenomic next-generation sequencing (mNGS) of fluid can identify pathogens (mNGS sensitivity 65.8% vs culture 36.8% in PD-related peritonitis; PMID: 39611142).

Clinical criteria / scoring. Diagnosis is clinical + imaging + fluid analysis. Severity/prognosis are graded by APACHE II and Mannheim Peritonitis Index (MPI), plus Sepsis-3/SOFA. Differential diagnosis: non-septic causes of acute abdomen (pancreatitis, ischemia without perforation, epiploic appendagitis, primary SBP, chemical peritonitis).

11. Outcome / Prognosis

Mortality. High and driven by source-control success and physiologic derangement. In severe secondary peritonitis, mortality was ~38%; APACHE II (19.6 vs 14.3; p=0.0015) and MPI (35.5 vs 27.8; p=0.001) were significantly higher in non-survivors, and MPI was the only independent multivariate risk factor (PMID: 21988045). Multivariate analysis of 604 IAI patients confirmed the prognostic dominance of host-related factors and the value of APACHE II and MPI (PMID: 8645072).

Source control is the dominant prognostic factor. In postoperative IAI, "in 37 of the patients the source of infection was eliminated resulting in 7 deaths (19%); all 11 of those in whom it was not eliminated died" (PMID: 8891619).

Prognostic factors: age, physiologic severity (APACHE II, SOFA), MPI, adequacy/timeliness of source control, organ dysfunction, fungal involvement (worse outcomes; PMID: 38691220), and serial peritoneal-fluid variables (in dogs, lower abdominal-fluid WBC and higher blood-to-fluid WBC/neutrophil ratios predicted recurrent septic peritonitis; PMID: 27556266).

Complications: septic shock, MODS (AKI, ARDS, septic cardiomyopathy, DIC, hepatic dysfunction), intra-abdominal abscess/adhesions, tertiary peritonitis, secondary/nosocomial infection, and long-term post-sepsis morbidity.

12. Treatment

Two pillars: source control + early antibiotics/resuscitation.

Surgical / interventional source control (the therapeutic gold standard). "The 'old' surgical source control consisting of debridement, removal of infected devices, drainage of purulent cavities, and decompression of the abdominal cavity is the gold standard of surgical care" (PMID: 30685836). Modalities include exploratory laparotomy with repair/resection of the perforated viscus, peritoneal lavage, percutaneous abscess drainage, and open-abdomen management. Vacuum-assisted closure (VAC) is a feasible open-abdomen technique in veterinary septic peritonitis (PMID: 22474052). NCIT suggestions: NCIT:C15329 (Surgery), NCIT:C51674 (Drainage Procedure), NCIT:C157715 (Debridement). Note: rapid source-control laparotomy is not universally beneficial and should be applied selectively (PMID: 28846501).

Pharmacotherapy — empiric broad-spectrum antibiotics. Cover Gram-negative enterics and anaerobes (± enterococci/fungi by risk). Agents shown effective against peritoneal isolates include cefotaxime, ceftazidime, and imipenem (PMID: 30040445); typical human regimens include beta-lactam/beta-lactamase inhibitors, carbapenems, or cephalosporin+metronidazole, with antifungals for upper-GI/tertiary disease. Duration: the landmark STOP-IT RCT found "four days of antibiotics for source-controlled complicated intra-abdominal infection resulted in similar outcomes when compared with a longer duration," including in high-risk patients (PMID: 27670577). NCIT: NCIT:C258 (Antibiotic), NCIT:C1878 (Imipenem), NCIT:C1737 (Cefotaxime).

Supportive/critical care. Fluid resuscitation, vasopressors, source-directed antibiotics, organ support (renal replacement therapy, mechanical ventilation, inotropes/mechanical support for septic cardiomyopathy — as in the multimodal rescue described in PMID: 42260799), and nutritional support, per Surviving Sepsis principles.

Experimental / adjunctive therapeutics (model-stage). Immunomodulation strategies tested in CLP and other models include soluble CD6 receptor (PMID: 27895015), the hCG-related peptide LQGV (PMID: 20890188), trophoblast stem cells (PMID: 40691621), CD300ld-based neutrophil enhancement (PMID: 40376837), and trained-immunity neutrophil reprogramming (PMID: 41980372). None are yet standard human therapy. For PD-associated recurrent peritonitis, taurolidine-urokinase lock therapy shows promise (PMID: 40988813).

Pharmacogenomics / gene / cell / RNA / targeted / immunotherapy: NOT APPLICABLE as approved disease-specific therapies.

13. Prevention

Primary prevention: treat/prevent predisposing GI disease (peptic ulcer prophylaxis, judicious NSAID/steroid use, timely management of appendicitis/diverticulitis), aseptic technique for PD catheters, and prompt surgery for at-risk lesions. There is no vaccine.
Secondary prevention: early recognition and treatment of GI perforation/ischemia before diffuse peritonitis develops; sepsis screening protocols.
Tertiary prevention: meticulous source control, appropriate antibiotic stewardship (STOP-IT short-course), prevention of secondary/nosocomial infection during the immunosuppressive phase, and monitoring for abscess/adhesion complications.
Public health: access to timely surgical and critical care is the key determinant of survival and the main lever for reducing geographic mortality disparities.
Genetic screening / counseling / immunization: NOT APPLICABLE.

14. Other Species / Natural Disease

Septic peritonitis is a common, high-mortality naturally occurring disease in companion animals, making veterinary data unusually informative.

Taxonomy: dog (Canis lupus familiaris, NCBI:txid9615), cat (Felis catus, NCBI:txid9685); mouse (Mus musculus, NCBI:txid10090) and rat as experimental hosts; zebrafish (Danio rerio, NCBI:txid7955) as a peritonitis model host.
Natural disease: "Septic peritonitis is a common, life-threatening condition encountered in dogs and cats" (PMID: 30040445). In GI-perforation cases, "the overall mortality was 63.6%" across 44 dogs and 11 cats (PMID: 24283417). Etiologies mirror humans: GI perforation (foreign bodies, NSAID-induced pyloric ulcer, dehiscence), with uncommon causes such as grass-awn foreign-body migration (good-to-excellent prognosis after surgery; PMID: 36874536).
Comparative biology: the pathophysiology (GI disruption → polymicrobial contamination → sepsis), diagnostics (blood-to-fluid glucose/lactate gradients, intracellular bacteria on cytology), and treatment (source control + antibiotics, open-abdomen/VAC) are strongly conserved between humans and companion animals — a key rationale for cross-species translational study.
Zoonotic potential: the enteric pathogens involved can be zoonotic, but septic peritonitis itself is not a transmissible disease.

15. Model Organisms

Gold-standard model — Cecal Ligation and Puncture (CLP). "Cecal ligation and puncture (CLP)... is often considered the 'gold standard' to induce polymicrobial sepsis in laboratory animals. CLP is a well-described model involving a simple surgical procedure that closely mimics the clinical course of intra-abdominal sepsis" (PMID: 34048005). Severity is tunable: e.g., 40% cecal ligation with double puncture yields ~80% mortality within 5 days, and 80% ligation ~100% mortality (PMID: 20890188).

Other models. - Cecal slurry (CS) intraperitoneal injection — the gold standard for neonatal mice (PMID: 34048005). - Zebrafish bacterial peritonitis — used to study neutrophil trained immunity (PMID: 41980372). - Genetic knockout/transgenic mice on the CLP background dissect mechanism (e.g., Nlrc4−/−, PMID: 41071588; CD300ld, PMID: 40376837).

Phenotype recapitulation & applications. CLP reproduces the polymicrobial source, the biphasic hyper- then immuno-suppressive host response (PMID: 31259890), cytokine kinetics, bacterial dissemination, and organ injury, enabling study of immunopathology and candidate therapeutics.

Limitations. Model outcomes are highly sensitive to technical variables — notably housing temperature: thermoneutral (30°C) housing improved CLP survival from 40% to 78% versus standard 22°C, altering IL-6 and phagocytosis (PMID: 32433210). Mouse models incompletely capture human comorbidity, age, and the effect of source control/antibiotics — a recognized reason for translational failure of sepsis immunotherapies.

Mechanistic Model / Interpretation

   GI-tract lesion (perforation / ischemia / dehiscence / trauma)
 │  spillage of luminal gut flora
 ▼
   Contamination of sterile peritoneum (polymicrobial: E. coli, anaerobes, Candida)
 │  PAMPs (LPS) → TLR4/CD14 → NF-κB (resident macrophages, mesothelium)
 ▼
   Cytokine storm: TNF-α, IL-1β, IL-6, HMGB1  +  neutrophil recruitment
     ┌────────────┴─────────────┐
   BRANCH A (local)               BRANCH B (systemic)
   coagulation > fibrinolysis     dysregulated host response = SEPSIS
   → fibrin, adhesions,           → vasodilation, capillary leak,
     abscess (walled-off             microthrombosis, hypoperfusion
     protected niche)             → septic shock
     │                          │
     └──────────► MULTIPLE ORGAN DYSFUNCTION (AKI, ARDS,
          septic cardiomyopathy, DIC, hepatic) ◄──────┐
                        │                              │
          hyperinflammatory → IMMUNOSUPPRESSIVE phase  │
                        │  secondary/tertiary infection┘
                        ▼
          DEATH  ◄── interrupted by ──►  SOURCE CONTROL + ANTIBIOTICS → recovery

The unifying theme is that septic peritonitis is a source-control disease: every downstream mechanistic step is fueled by ongoing contamination from the GI lesion, so physically eliminating the source (with antibiotic and physiologic support) is both the most upstream and the most effective intervention — explaining why source-control success dominates every prognostic model.

Evidence Base

PMID	Role	Key contribution
39200076	Supports	IAI mortality 23–38%; 2nd most common sepsis death
37170123	Supports	SCIAS mortality >80%; GI-disruption→MODS causal chain
30685836	Supports	Sepsis-3 definition; abdomen 2nd source; source-control gold standard
31954465	Supports	Global sepsis burden (48.9M cases, 11M deaths, GBD 2017)
41227298	Supports	Secondary peritonitis subtypes; biomarker panel
8891619	Supports	Source control determines survival (19% vs 100% mortality)
21988045	Supports	APACHE II & MPI discriminate survivors; MPI independent
8645072	Supports	604-patient multivariate validation of scoring systems
27670577	Supports	STOP-IT: 4-day antibiotics suffice after source control
22752330	Supports	CT free air+fluid → surgery for generalized peritonitis
15093233	Supports	Free intraperitoneal air = direct perforation sign
42583660	Supports	Classic peritoneal signs of acute abdomen
12692761	Supports	Blood-to-fluid glucose/lactate gradients 100% Se/Sp (dogs)
12734857	Supports	Coagulation shift → abscess/adhesion mechanism
34048005	Supports	CLP as gold-standard polymicrobial sepsis model
31259890	Supports	Biphasic immune course; immunosuppressive phase
24283417	Supports	Companion-animal mortality 63.6%; NSAID risk factor
30040445	Supports	Veterinary microbiology; effective antibiotics
32433210	Qualifies	Housing temperature drastically alters CLP outcomes (model limitation)
28846501	Qualifies	Rapid source-control laparotomy not universally beneficial

Limitations and Knowledge Gaps

Template mismatch. Roughly half the standard disease template (causal genes, pathogenic variants, inheritance, penetrance, chromosomal/epigenetic diagnostics, genetic counseling, vaccination) is not applicable to an acquired infectious/surgical condition. These are documented as N/A rather than forced.
Human vs veterinary diagnostic evidence. The most striking quantitative diagnostic data (blood-to-fluid glucose/lactate 100% Se/Sp) come from canine/feline cohorts; the exact human cutoffs differ and human peritoneal-fluid gradient thresholds are less standardized.
Heterogeneity. "Septic peritonitis" spans primary (SBP), secondary (the main entity here), and tertiary forms, and multiple GI source lesions with different microbiology and prognosis — pooling can obscure subtype-specific detail.
Immunotherapy translation. Numerous adjunctive immunomodulators succeed in CLP but none is approved for human peritonitis; model artifacts (e.g., housing temperature) contribute to this translational gap.
Host-genetic modifiers of the sepsis response are biologically plausible but not yet clinically actionable for peritonitis.

Proposed Follow-up Experiments / Actions

Standardize human peritoneal-fluid biochemical gradients (glucose, lactate, pH) prospectively to replicate the high-performing veterinary diagnostics in people.
Subtype-stratified prognostic modeling integrating MPI/APACHE II with the biomarker panel (PCT, IL-6, HMGB1, NLR, NGAL) to individualize source-control urgency and antibiotic duration.
Validate short-course/biomarker-guided antibiotic stopping (building on STOP-IT) across the fungal-peritonitis and immunosuppressed subgroups.
Cross-species translational studies leveraging naturally occurring canine/feline septic peritonitis as a bridge between CLP and human trials for candidate immunotherapies (e.g., neutrophil-directed CD300ld, trained immunity).
Standardize CLP reporting (housing temperature, ligation length, resuscitation/antibiotic co-treatment) to improve reproducibility and translational fidelity.
Investigate host-genetic and mNGS-guided personalization — combine rapid pathogen metagenomics with host inflammatory profiling to tailor antimicrobial and immunomodulatory therapy.

Report compiled from 13 confirmed findings and 58 reviewed papers across a 5-iteration autonomous investigation. Evidence sources: human clinical cohorts and guidelines, veterinary clinical cohorts (naturally occurring disease), and experimental animal models (CLP, cecal slurry, zebrafish).

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.3.0rc3.

Outcome	Count
References checked	39
Resolved	39
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	15
Quoted claims found in source	15
Quoted claims not found in source	0
References weighed for topical relevance	39
On topic	27
Off topic	0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome	Count
Terms checked	49
Resolved	49
Unresolved (possible confabulation)	0
Obsolete	0
Unverifiable	0
Terms whose name was checked	27
Terms named correctly	16
Terms named as a different term	6
Terms whose name is worth a second look	5

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

HP:0025380 (1 mention) - the report calls it "Abdominal guarding"; HP calls it Increased circulating androstenedione concentration
CL:0000771 (2 mentions) - the report calls it "B-1a cell"; CL calls it eosinophil
NCIT:C51674 (1 mention) - the report calls it "Drainage Procedure"; NCIT calls it Endomyocardial Biopsy
NCIT:C157715 (1 mention) - the report calls it "Debridement"; NCIT calls it Total Gut Decontamination
NCIT:C1878 (1 mention) - the report calls it "Imipenem"; NCIT calls it Darbepoetin Alfa
NCIT:C1737 (1 mention) - the report calls it "Cefotaxime"; NCIT calls it Organic Solvents

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

HP:0002027 (2 mentions) - the report calls it "Abdominal pain", "Clinical sign"; HP calls it Abdominal pain
HP:0011227 (1 mention) - the report calls it "Elevated CRP"; HP calls it Elevated circulating C-reactive protein concentration, and lists "Elevated CRP" among its other names
GO:0007249 (1 mention) - the report calls it "NF-κB signaling"; GO calls it canonical NF-kappaB signal transduction, and lists "p50-dependent NF-kappaB signaling" among its other names
GO:0070269 (1 mention) - the report calls it "pyroptosis"; GO calls it pyroptotic inflammatory response, and lists "pyroptosis" among its other names
GO:0042060 (1 mention) - the report calls it "wound healing/adhesion"; GO calls it wound healing

Terms named inconsistently

The report gives these identifiers more than one name of its own:

HP:0002027 - called "Abdominal pain", "Clinical sign"

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Classifications

Pathophysiology

Pathograph

Phenotypes

Medical Actions

Biochemical Markers

Diagnosis

Progression

Infectious Agent

Transmission

Clinical Burden

Animal Models

Source YAML

References & Deep Research

Deep Research

Septic Peritonitis (MONDO:0005195): A Comprehensive Disease Characterization Report

Summary

1. Disease Information

2. Etiology

3. Phenotypes

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation)

Category detail

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome / Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Mechanistic Model / Interpretation

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Experiments / Actions

Artifacts

Reference Validation

Term Validation

Terms the report names something else

Terms whose name is worth a second look

Terms named inconsistently