Mycoplasma Pneumoniae Pneumonia

Infectious Disease MONDO:0005867 Pathograph 5 Show in embeddings browser Bacterial Respiratory Infection

Mycoplasma pneumoniae pneumonia is an atypical ("walking") pneumonia caused by Mycoplasma pneumoniae, a leading cause of community-acquired pneumonia in school-aged children and young adults. M. pneumoniae adheres to and damages the respiratory epithelium and characteristically lacks a bacterial cell wall, which makes it intrinsically resistant to beta-lactam antibiotics and dictates treatment with protein-synthesis inhibitors (macrolides, tetracyclines) or fluoroquinolones. Acquired macrolide resistance is an increasing problem.

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4
Pathophys.
3
Phenotypes
5
Pathograph
1
Medical Actions
⚙

Pathophysiology

4
Airway Epithelial Adherence and Atypical Pneumonia
M. pneumoniae attaches to the respiratory epithelium via specialized adhesins and damages the airway surface, producing an atypical pneumonia. It is a leading cause of community-acquired pneumonia in school-aged children and young adults, often with a protracted, relatively mild ("walking") course.
respiratory epithelial cell CL:0002632 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves respiratory epithelial cell, annotated with epithelial cell of lower respiratory tract (CL:0002632). CL:0002632 is a cell type from the Cell Ontology.
adhesion of symbiont to host GO:0044406 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves adhesion of symbiont to host (GO:0044406). GO:0044406 is a biological process from the Gene Ontology. inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED
lung UBERON:0002048 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in lung (UBERON:0002048). UBERON:0002048 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Cell-Wall Deficiency and Intrinsic Beta-Lactam Resistance The organism's lack of a cell wall removes the beta-lactam target, determining antibiotic selection.
Bacterial Ribosomal Translation (Macrolide Target) Treatment instead targets bacterial ribosomal protein synthesis.
Show evidence (1 reference)
PMID:39475213 SUPPORT Other
"Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia among school-aged children and young adults."
Establishes M. pneumoniae as a leading cause of community-acquired pneumonia in children and young adults. Evidence source is OTHER as this is a review article.
Cell-Wall Deficiency and Intrinsic Beta-Lactam Resistance
M. pneumoniae has no peptidoglycan cell wall, so the penicillin-binding-protein target of beta-lactam antibiotics does not exist. The organism is therefore intrinsically resistant to beta-lactams, which is why cell-wall-active drugs are useless and treatment relies on agents that act on other targets.
response to antibiotic GO:0046677 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves response to antibiotic (GO:0046677). GO:0046677 is a biological process from the Gene Ontology.
Show evidence (2 references)
PMID:39475213 SUPPORT Other
"The lack of a cell wall and reduced metabolic pathways limit the options for antibiotic treatment."
States that M. pneumoniae's lack of a cell wall limits antibiotic options, the intrinsic-resistance principle this node represents. Evidence source is OTHER as this is a review article.
PMID:34750083 SUPPORT Other
"most atypical pathogens do not have a bacterial cell wall, some are intracellular (e.g., Legionella), and some are paracellular (e.g., M. pneumoniae)"
Confirms M. pneumoniae lacks a bacterial cell wall, removing the beta-lactam target. Evidence source is OTHER as this is a review article.
Bacterial Ribosomal Translation (Macrolide Target)
Lacking a cell-wall target, M. pneumoniae is treated with antibiotics that act on its 70S ribosome. Macrolides (e.g., azithromycin) bind the 50S ribosomal subunit and block bacterial protein synthesis — the molecular target that makes a macrolide, rather than a beta-lactam, first-line therapy.
translation GO:0006412 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves translation (GO:0006412). GO:0006412 is a biological process from the Gene Ontology.
Downstream
Acquired Macrolide Resistance Mutations at the ribosomal macrolide-binding site confer acquired resistance.
Show evidence (1 reference)
PMID:24336183 SUPPORT Other
"The ribosome is one of the main antibiotic targets in the bacterial cell."
Establishes the bacterial ribosome as the target of macrolides and other protein-synthesis inhibitors, the step this node represents. Evidence source is OTHER as this is a review article.
Acquired Macrolide Resistance
Acquired macrolide resistance, driven by mutations in the 23S rRNA macrolide-binding site, is an increasing problem in M. pneumoniae and can necessitate switching to a tetracycline or fluoroquinolone.
response to antibiotic GO:0046677 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves response to antibiotic (GO:0046677). GO:0046677 is a biological process from the Gene Ontology.
Show evidence (1 reference)
PMID:39475213 SUPPORT Other
"Acquired macrolide resistance is a growing concern, with >80% of cases in China being macrolide-resistant."
Documents acquired macrolide resistance as a growing concern, the ribosomal-target-resistance escape this node represents. Evidence source is OTHER as this is a review article.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Mycoplasma Pneumoniae Pneumonia Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

3
Immune 1
Atypical Pneumonia HP:0002090 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pneumonia (HP:0002090). HP:0002090 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39475213 SUPPORT Other
"Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia among school-aged children and young adults."
Supports community-acquired pneumonia as the defining manifestation. Evidence source is OTHER as this is a review article.
Metabolism 1
Fever HP:0001945 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fever (HP:0001945). HP:0001945 is a phenotype from the Human Phenotype Ontology.
Respiratory 1
Cough HP:0012735 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cough (HP:0012735). HP:0012735 is a phenotype from the Human Phenotype Ontology.
💊

Medical Actions

1
Azithromycin
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: azithromycin CHEBI:2955 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses azithromycin (CHEBI:2955). CHEBI:2955 is a therapeutic agent from Chemical Entities of Biological Interest.
Macrolide antibiotic that inhibits bacterial protein synthesis at the 50S ribosomal subunit; first-line therapy for M. pneumoniae because the organism has no cell wall for beta-lactams to target. Empiric choice should account for rising macrolide resistance.
Mechanism Target:
INHIBITS Bacterial Ribosomal Translation (Macrolide Target) — Azithromycin binds the 50S ribosome and arrests bacterial protein synthesis, the molecular target that makes a macrolide first-line for cell-wall-less M. pneumoniae.
INHIBITS Airway Epithelial Adherence and Atypical Pneumonia — By halting protein synthesis, azithromycin clears the organism from the airway and resolves the atypical pneumonia.
{ }

Source YAML

click to show 
name: Mycoplasma Pneumoniae Pneumonia
creation_date: "2026-06-28T00:00:00Z"
description: >
  Mycoplasma pneumoniae pneumonia is an atypical ("walking") pneumonia caused by
  Mycoplasma pneumoniae, a leading cause of community-acquired pneumonia in
  school-aged children and young adults. M. pneumoniae adheres to and damages the
  respiratory epithelium and characteristically lacks a bacterial cell wall, which
  makes it intrinsically resistant to beta-lactam antibiotics and dictates
  treatment with protein-synthesis inhibitors (macrolides, tetracyclines) or
  fluoroquinolones. Acquired macrolide resistance is an increasing problem.
category: Infectious Disease
parents:
- Bacterial Respiratory Infection
synonyms:
- Mycoplasma pneumonia
- Atypical pneumonia (Mycoplasma)
- Walking pneumonia
disease_term:
  preferred_term: Mycoplasma pneumoniae pneumonia
  term:
    id: MONDO:0005867
    label: Mycoplasma pneumoniae pneumonia
pathophysiology:
- name: Airway Epithelial Adherence and Atypical Pneumonia
  role: trigger
  description: >
    M. pneumoniae attaches to the respiratory epithelium via specialized adhesins
    and damages the airway surface, producing an atypical pneumonia. It is a
    leading cause of community-acquired pneumonia in school-aged children and young
    adults, often with a protracted, relatively mild ("walking") course.
  cell_types:
  - preferred_term: respiratory epithelial cell
    term:
      id: CL:0002632
      label: epithelial cell of lower respiratory tract
  biological_processes:
  - preferred_term: adhesion of symbiont to host
    term:
      id: GO:0044406
      label: adhesion of symbiont to host
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
    modifier: INCREASED
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:39475213
    reference_title: "Mycoplasma pneumoniae: not a typical respiratory pathogen."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia
      among school-aged children and young adults.
    explanation: >-
      Establishes M. pneumoniae as a leading cause of community-acquired pneumonia
      in children and young adults. Evidence source is OTHER as this is a review
      article.
  downstream:
  - target: Cell-Wall Deficiency and Intrinsic Beta-Lactam Resistance
    description: >-
      The organism's lack of a cell wall removes the beta-lactam target,
      determining antibiotic selection.
  - target: Bacterial Ribosomal Translation (Macrolide Target)
    description: >-
      Treatment instead targets bacterial ribosomal protein synthesis.

- name: Cell-Wall Deficiency and Intrinsic Beta-Lactam Resistance
  role: intrinsic_resistance
  conforms_to: "bacterial_cell_wall_synthesis_inhibition#Intrinsic Resistance in Cell-Wall-Deficient Organisms"
  description: >
    M. pneumoniae has no peptidoglycan cell wall, so the penicillin-binding-protein
    target of beta-lactam antibiotics does not exist. The organism is therefore
    intrinsically resistant to beta-lactams, which is why cell-wall-active drugs
    are useless and treatment relies on agents that act on other targets.
  biological_processes:
  - preferred_term: response to antibiotic
    term:
      id: GO:0046677
      label: response to antibiotic
  evidence:
  - reference: PMID:39475213
    reference_title: "Mycoplasma pneumoniae: not a typical respiratory pathogen."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The lack of a cell wall and reduced metabolic pathways limit the options for
      antibiotic treatment.
    explanation: >-
      States that M. pneumoniae's lack of a cell wall limits antibiotic options,
      the intrinsic-resistance principle this node represents. Evidence source is
      OTHER as this is a review article.
  - reference: PMID:34750083
    reference_title: "Atypical pneumonia: Pathophysiology, diagnosis, and treatment."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      most atypical pathogens do not have a bacterial cell wall, some are
      intracellular (e.g., Legionella), and some are paracellular (e.g., M.
      pneumoniae)
    explanation: >-
      Confirms M. pneumoniae lacks a bacterial cell wall, removing the beta-lactam
      target. Evidence source is OTHER as this is a review article.
  downstream: []

- name: Bacterial Ribosomal Translation (Macrolide Target)
  role: therapeutic_vulnerability
  conforms_to: "bacterial_protein_synthesis_inhibition#Bacterial mRNA Translation by the Ribosome"
  description: >
    Lacking a cell-wall target, M. pneumoniae is treated with antibiotics that act
    on its 70S ribosome. Macrolides (e.g., azithromycin) bind the 50S ribosomal
    subunit and block bacterial protein synthesis — the molecular target that makes
    a macrolide, rather than a beta-lactam, first-line therapy.
  biological_processes:
  - preferred_term: translation
    term:
      id: GO:0006412
      label: translation
  evidence:
  - reference: PMID:24336183
    reference_title: Ribosome-targeting antibiotics and mechanisms of bacterial resistance.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The ribosome is one of the main antibiotic targets in the bacterial cell.
    explanation: >-
      Establishes the bacterial ribosome as the target of macrolides and other
      protein-synthesis inhibitors, the step this node represents. Evidence source
      is OTHER as this is a review article.
  downstream:
  - target: Acquired Macrolide Resistance
    description: >-
      Mutations at the ribosomal macrolide-binding site confer acquired resistance.

- name: Acquired Macrolide Resistance
  role: adaptive_escape
  conforms_to: "bacterial_protein_synthesis_inhibition#Ribosomal Target Resistance"
  description: >
    Acquired macrolide resistance, driven by mutations in the 23S rRNA
    macrolide-binding site, is an increasing problem in M. pneumoniae and can
    necessitate switching to a tetracycline or fluoroquinolone.
  biological_processes:
  - preferred_term: response to antibiotic
    term:
      id: GO:0046677
      label: response to antibiotic
  evidence:
  - reference: PMID:39475213
    reference_title: "Mycoplasma pneumoniae: not a typical respiratory pathogen."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Acquired macrolide resistance is a growing concern, with >80% of cases in
      China being macrolide-resistant.
    explanation: >-
      Documents acquired macrolide resistance as a growing concern, the
      ribosomal-target-resistance escape this node represents. Evidence source is
      OTHER as this is a review article.
  downstream: []
phenotypes:
- category: Respiratory
  name: Atypical Pneumonia
  description: >
    Community-acquired atypical pneumonia, typically with a protracted, relatively
    mild ("walking") course.
  phenotype_term:
    preferred_term: Pneumonia
    term:
      id: HP:0002090
      label: Pneumonia
  evidence:
  - reference: PMID:39475213
    reference_title: "Mycoplasma pneumoniae: not a typical respiratory pathogen."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia
      among school-aged children and young adults.
    explanation: >-
      Supports community-acquired pneumonia as the defining manifestation.
      Evidence source is OTHER as this is a review article.
- category: Respiratory
  name: Cough
  description: >
    A persistent, often dry cough is the hallmark symptom of M. pneumoniae
    infection.
  phenotype_term:
    preferred_term: Cough
    term:
      id: HP:0012735
      label: Cough
- category: Constitutional
  name: Fever
  description: >
    Fever commonly accompanies acute M. pneumoniae infection.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
treatments:
- name: Azithromycin
  description: >
    Macrolide antibiotic that inhibits bacterial protein synthesis at the 50S
    ribosomal subunit; first-line therapy for M. pneumoniae because the organism
    has no cell wall for beta-lactams to target. Empiric choice should account for
    rising macrolide resistance.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: azithromycin
      term:
        id: CHEBI:2955
        label: azithromycin
  target_mechanisms:
  - target: Bacterial Ribosomal Translation (Macrolide Target)
    treatment_effect: INHIBITS
    description: >-
      Azithromycin binds the 50S ribosome and arrests bacterial protein synthesis,
      the molecular target that makes a macrolide first-line for cell-wall-less
      M. pneumoniae.
  - target: Airway Epithelial Adherence and Atypical Pneumonia
    treatment_effect: INHIBITS
    description: >-
      By halting protein synthesis, azithromycin clears the organism from the
      airway and resolves the atypical pneumonia.
notes: >
  Created as part of the Respiratory Infections project. Worked conformer for the
  bacterial_cell_wall_synthesis_inhibition module's intrinsic-resistance branch
  (cell-wall-deficient organism) and for the bacterial_protein_synthesis_inhibition
  module (ribosomal target + acquired macrolide resistance). The infectious_agent
  (NCBITaxon) block was omitted at creation and the organism is described in the
  text.