Incidence of anaerobes in ventilator-associated pneumonia with use of a protected specimen brush

The role of anaerobic bacteria in ventilator-associated pneumonia (VAP) has been little investigated. In this study we analyzed the incidence of anaerobes in patients with a first episode of bacteriologically documented VAP (10(3)CFU/ml), using protected specimen brushes (PSB). We particularly took care to preserve anaerobic conditions during transport and the microbiological procedure. Two groups were considered: group A with anaerobic bacteria recovered from PSB, with or without anaerobes, and group B with aerobic bacteria only. One hundred and thirty patients were included, 30 (23%) in group A, and 100 (77%) in group B. The main anaerobic strains isolated were Prevotella melaninogenica (36%), Fusobacterium nucleatum (17%), and Veillonella parvula (12%). Univariate analysis demonstrated that patients in group A were younger than those in group B (p0.05) and their simplified acute physiologic score was higher (p0.02). The percentage of patients receiving antibiotics before PSB did not differ significantly between group A (57%) and group B (35%). VAP with anaerobes occurred more often in patients orotracheally intubated than nasotracheally intubated (p0.02). Episodes of VAP involving anaerobic bacteria occurred more often in the first five days (early VAP) than after the fifth day (late VAP) (p0.05). The 3-mo mortality rate was similar in the two groups, but death occurred earlier in group B (p0.01). Multivariate analysis demonstrated that presence of altered level of consciousness (p = 0.0002), higher simplified acute physiologic score (p = 0.003), and admission to the medical ICU (p = 0.02) were the factors independently predisposing to the development of VAP with anaerobes.