Bacteriology of aspiration pneumonia in patients with acute coma

Loss of protective airway reflexes in patients with acute coma puts these patients at risk of aspiration pneumonia complicating the course of the primary disease. Available data vary considerably with regard to bacteriology, role of anaerobic bacteria, and antibiotic treatment. Our objective was to research the bacteriology of aspiration pneumonia in acute coma patients who were not pre-treated with antibiotics or hospitalized within 30 days prior to the event. We prospectively analyzed 127 patient records from adult patients admitted, intubated and ventilated to a tertiary medical intensive care unit with acute coma. Bacteriology and antibiotic resistance testing from tracheal aspirate sampled within 24 h after admission, blood cultures, ICU scores (APACHE II, SOFA), hematology, and clinical chemistry were assessed. Patients were followed up until death or hospital discharge. The majority of patients with acute coma suffered from acute cardiovascular disorders, predominantly myocardial infarction, followed by poisonings, and coma of unknown cause. In a majority of our patients, microaspiration resulted in overt infection. Most frequently S. aureus, H. influenzae, and S. pneumoniae were isolated. Anaerobic bacteria (Bacteroides spec., Fusobacteria, Prevotella spec.) were isolated from tracheal aspirate in a minority of patients, and predominantly as part of a mixed infection. Antibiotic monotherapy with a 2nd generation cephalosporin, or a 3rd generation gyrase inhibitor, was most effective in our patients regardless of the presence of anaerobic bacteria.