Aspiration risk factors, microbiology and empiric antibiotics for patients hospitalized with community-acquired pneumonia

Background: Aspiration community-acquired pneumonia (ACAP) and community-acquired pneumonia (CAP) in patients with aspiration risk factors (AspRFs) are infections associated with anaerobes, but limited evidence suggests their pathogenic role. Research question: What are the aspiration risk factors, microbiology patterns, and empiric anti-anaerobic use in patients hospitalized with CAP? Study design and methods: This is a secondary analysis of GLIMP, an international, multicenter, point-prevalence study of adults hospitalized with CAP. Patients were stratified into three groups: 1) ACAP, 2) CAP/AspRF+ (CAP with AspRF) and 3) CAP/AspRF- (CAP without AspRF). Data on demographics, comorbidities, microbiological results, and anti-anaerobic antibiotics were analyzed in all groups. Patients were further stratified in severe and non-severe CAP groups. Results: We enrolled 2,606 patients with CAP, of which 193 (7.4%) had ACAP. Risk factors independently associated with ACAP were male, bedridden, underweight, a nursing home resident, and having a history of stroke, dementia, mental illness, and enteral tube feeding. Among non-ACAP patients, 1,709 (70.8%) had CAP/AspRF+ and 704 (29.2%) had CAP/AspRF-. Microbiology patterns including anaerobes were similar between CAP/AspRF-, CAP/AspRF+ and ACAP (0.0% vs. 1.03% vs. 1.64%). Patients with severe ACAP had higher rates of total Gram-negative bacteria (64.3% vs. 44.3% vs. 33.3%, p=0.021) and lower rates of total Gram-positive bacteria (7.1% vs. 38.1% vs. 50.0%, p<0.001) when compared to patients with severe CAP/AspRF+ and severe CAP/AspRF-, respectively. The majority of the patients (>50% in all groups) independent of AspRFs or ACAP received specific or broad-spectrum anti-anaerobic coverage antibiotics. Interpretation: Hospitalized patients with ACAP or CAP/AspRF+ had similar anaerobic flora compared to patients without aspiration risk factors. Gram-negative bacteria were more prevalent in patients with severe ACAP. Despite having similar microbiological flora between groups, a large proportion of CAP patients received anti-anaerobic antibiotic coverage.