Aspiration pneumonia - Pulmonary
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Synopsis
The infection is often polymicrobial, including oropharyngeal anaerobic bacteria and aerobic bacteria, but gram-negative bacilli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, Haemophilus influenzae, and Enterobacteriaceae are not uncommon, particularly in individuals exposed to a health care setting.
Typical bacterial aspiration pneumonia evolves with an indolent course over several days to weeks with foul-smelling sputum, low-grade fever, and malaise. Patients commonly have periodontal disease or some degree of underlying neurologic disease and may have associated weight loss and anemia. Hospital-acquired aspiration pneumonia may develop more rapidly based on bacterial organisms. Complications include necrotizing pneumonia, lung abscesses, acute respiratory distress syndrome, and empyema.
Predisposing conditions include dysphagia as it relates to neurologic or esophageal disorders, mechanical obstruction of glottic closure, impaired consciousness including resulting from alcohol and drug abuse, seizures, head trauma, and cerebrovascular accidents.
Aspiration pneumonia should be distinguished from chemical pneumonitis, which refers to the aspiration of toxins into the lower airways and is associated with abrupt onset of dyspnea, low-grade fever, hypoxemia, and diffuse crackles on lung exam within 8-24 hours of aspiration event.
Codes
ICD10CM:J69.8 – Pneumonitis due to inhalation of other solids and liquids
SNOMEDCT:
422588002 – Aspiration pneumonia
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Community-acquired pneumonia (or health care-associated pneumonia) due to bacterial pathogens (eg, Streptococcus pneumoniae, S. aureus pneumonia)
- Aspiration pneumonitis can be difficult to distinguish from aspiration pneumonia early in the course.
- Chemical pneumonitis
- Pneumonia due to the endemic fungi (eg, histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, cryptococcosis)
- Invasive fungal infections (aspergillosis, mucormycosis) can present with cavitary lung lesions in immunosuppressed hosts.
- Pneumonia due to other pathogens including Legionella or Nocardia
- Tuberculosis can present with cavitary lung lesions.
- Malignancy (primary lung cancer or metastases) can present with cavitary lung lesions.
- Lung infarct (for example following pulmonary embolism) can sometimes cavitate.
- Granulomatosis with polyangiitis can present with cavitary lung lesions.
- Pulmonary edema
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References
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Last Reviewed:03/01/2017
Last Updated:09/30/2019
Last Updated:09/30/2019