Aspiration Pneumonia Pathogens and Management

Pathogen Profile by Clinical Setting

The American Thoracic Society recommends considering Streptococcus pneumoniae and Haemophilus influenzae as the most common pathogens in community-acquired aspiration pneumonia, particularly in patients with a history of smoking or COPD 1, 2
The Infectious Diseases Society of America suggests that enteric gram-negative bacilli, such as E. coli and Klebsiella pneumoniae, are found in patients with oropharyngeal colonization by these organisms 1, 2
The American College of Chest Physicians states that Staphylococcus aureus, including MRSA, is increasingly common in nosocomial aspiration pneumonia, particularly in ICU patients or those with diabetes or head trauma 3, 4, 5
The Society for Healthcare Epidemiology of America recommends considering Pseudomonas aeruginosa in patients with structural lung disease, prior antibiotics, or prolonged hospitalization 3, 6, 7

The Centers for Disease Control and Prevention suggests that antimicrobial therapy within the preceding 90 days, current hospitalization ≥5 days, or hospitalization for ≥2 days in the preceding 90 days mandates coverage for resistant organisms 4
The American Thoracic Society recommends considering residence in a nursing home or extended care facility, chronic dialysis within 30 days, home infusion therapy, or immunosuppressive disease or therapy as risk factors for multidrug-resistant pathogens 4, 7

The Infectious Diseases Society of America states that anaerobic coverage is not recommended for routine aspiration pneumonia in inpatient settings, except in cases of lung abscess, necrotizing pneumonia, or empyema 8

In nursing home residents with aspiration, S. aureus (29%), enteric gram-negative rods (15%), S. pneumoniae (9%), and Pseudomonas species (4%) were most frequently isolated 9
The American Thoracic Society notes that anaerobic organisms may follow aspiration in nonintubated patients, but are rare in patients with ventilator-associated pneumonia 9
Enteric gram-negative bacilli (E. coli, Klebsiella, Acinetobacter) are common in hospital-acquired cases 9
In elderly nursing home residents who failed initial antibiotic therapy, MRSA (33%), gram-negative enterics (24%), and Pseudomonas (14%) were most frequent 9

Antimicrobial therapy within preceding 90 days is the strongest predictor, according to the American Journal of Respiratory and Critical Care Medicine 9
Current hospitalization ≥5 days or hospitalization for ≥2 days in preceding 90 days increases the risk of multidrug-resistant pathogens 9
Nursing home residence or extended care facility is a risk factor for multidrug-resistant pathogens 9
Severe CAP requiring ICU admission should prompt coverage for upper airway colonizers including gram-negative pathogens and S. aureus, as recommended by Pharmacology and Therapeutics 10