Microbiology and prognosis assessment of hospitalized patients with aspiration pneumonia: a single-center prospective cohort study.

Aspiration pneumonia has a high incidence in hospitalized patients with community-acquired pneumonia and results in high mortality rates. We aimed to evaluate microbiology and assess prognostic factors of aspiration pneumonia in the setting of a tertiary hospital pulmonology department. Community-acquired (CAAP) and healthcare-associated aspiration pneumonia (HCAAP) cases hospitalized over a period of a year were prospectively followed. Demographic, clinical, biological and radiological data were recorded at admission, while sputum, tracheal aspirates or bronchial washing samples were collected within 48 hours of admission. During hospital stay, therapeutic and supportive measures and resulting complications were recorded. Regression analysis was applied to find statistically significant prognostic factors. The sample consisted of 70 patients (67.1% men); 55.7% of them presented as HCAAP; 94.3% had positive culture of lower respiratory tract specimens with isolation of 115 pathogens, 47 of which were multidrug- or extensively drug-resistant. The most common pathogens were Pseudomonas aeruginosa (37.1%), Klebsiella pneumoniae (27.1%), Staphylococcus aureus (25.7%) and Acinetobacter baumannii (20%). Empiric antimicrobial therapy was combination therapy in 70% and included antipseudomonal and MRSA-targeted antibiotics in 61.4% and 11.4%, respectively. Patients in the HCAAP group had a higher rate of antibiotics usage in the previous trimester, more frequent isolation of resistant strains and were more likely to receive inadequate empiric treatment than those in the CAAP group. In-hospital mortality was 52.2%; no difference between groups was noted. Independent factors of increased mortality were older age (p=0.004), low serum albumin levels (p=0.039), increased radiological involvement (p=0.050) and ineffective initial therapy (p=0.001). We concluded that patients hospitalized for aspiration pneumonia have frequent contact with healthcare services and acquire multidrug-resistant Gram-negative bacteria. Empiric therapy should target these specific microorganisms as its success determines the prognosis.