Aspiration Pneumonia is a lung infection that occurs when foreign material — most commonly oral or gastric contents (food, saliva, liquid, or stomach acid) — is inhaled into the lower airways and lungs, introducing bacteria and triggering an inflammatory infectious response.
It is distinct from aspiration pneumonitis (a chemical injury from aspirating sterile gastric acid without infection), though the two can overlap and progress from one to the other.
Who Is at Risk Aspiration pneumonia predominantly affects people with impaired swallowing or reduced protective airway reflexes:
- Altered consciousness — stroke, seizure, anesthesia, intoxication (alcohol/drugs)
- Neurological disorders — stroke, Parkinson’s disease, ALS, dementia, brain injury
- Dysphagia (swallowing dysfunction) — from any cause
- Mechanical ventilation / intubation
- Poor dentition / poor oral hygiene (increases bacterial load)
- Gastroesophageal reflux disease (GERD)
- Elderly patients (diminished cough and gag reflexes)
- Tube feeding
Causative Organisms Unlike community-acquired pneumonia, aspiration pneumonia often involves mixed flora from the oropharynx:
- Anaerobic bacteria — Bacteroides, Peptostreptococcus, Fusobacterium (especially in community settings)
- Gram-negative rods — Klebsiella, E. coli, Pseudomonas (especially in hospital settings)
- Streptococcus pneumoniae, Staphylococcus aureus (including MRSA in healthcare-associated cases)
Signs & Symptoms
- Cough — may produce foul-smelling or purulent sputum
- Fever and chills
- Shortness of breath and rapid breathing
- Chest pain (pleuritic)
- Hypoxia (low oxygen saturation)
- Crackles or decreased breath sounds on auscultation
- In severe cases — cyanosis, altered mental status, sepsis
Characteristic Location Aspirated material tends to settle by gravity into specific lung segments depending on the patient’s position:
- Upright/semi-recumbent — lower lobes (right > left, due to the more vertical angle of the right mainstem bronchus)
- Supine — posterior segments of upper lobes and superior segments of lower lobes
Diagnosis
- Chest X-ray or CT scan — infiltrates, consolidation, or abscess in dependent lung segments
- Sputum culture and blood cultures
- CBC — leukocytosis (elevated white cell count)
- Pulse oximetry / ABG (arterial blood gas) for oxygenation status
- Swallowing evaluation (speech-language pathology) to assess aspiration risk
Complications
- Lung abscess — necrotic cavity filled with pus; common with anaerobic infections
- Empyema — infected fluid collection in the pleural space
- Respiratory failure requiring mechanical ventilation
- Sepsis and septic shock
- Progression to ARDS (Acute Respiratory Distress Syndrome)
Treatment
- Antibiotics — tailored to setting and likely organisms
- Community-acquired: amoxicillin-clavulanate, clindamycin, or moxifloxacin (anaerobic coverage)
- Hospital/healthcare-acquired: broader coverage including gram-negatives and MRSA (piperacillin-tazobactam ± vancomycin)
- Supplemental oxygen and respiratory support as needed
- Chest physiotherapy
- Treat the underlying cause of aspiration
- Aspiration precautions — positioning (head of bed elevation ≥ 30°), thickened liquids, modified diet textures
- Lung abscess may require prolonged antibiotics or drainage
Aspiration pneumonia carries significant morbidity and mortality, particularly in elderly, neurologically impaired, or critically ill patients. Prevention — through careful feeding practices, oral hygiene, and positioning — is as important as treatment.