Ventilator associated pneumonia in a medical intensive care unit: Microbial aetiology, susceptibility patterns of isolated microorganisms and outcome

BACKGROUND: Ventilator-associated pneumonia (VAP) is a common complication of ventilatory support for patients with acute respiratory failure and is associated with increased morbidity and mortality. AIM OF THE STUDY: The present study was undertaken to do quantitative cultures of aerobic bacteria, perform the antibiotic susceptibility testing from the endotracheal aspirates and clinical outcome of the clinically suspected patients of VAP. METHODS: A prospective study was performed over a period of one year in a tertiary care hospital, enrolling patients on mechanical ventilation (MV) for ≥48 hr. Endotracheal aspirates (ETA) were collected from patients with suspected VAP, and direct gram's stain criteria was used to accept the sample. Quantitative cultures of ETA were performed with the threshold for microbiological diagnosis of VAP was taken as ≥10(5) colony forming units (cfu)/ml. RESULTS: Out of 53 cases, 2 (3.77%) were polymicrobial. Multidrug resistant bacteria, mainly Acinetobacter baumannii 49.09% (27/55) and Pseudomonas aeruginosa 30.91% (17/55) were the most common pathogens isolated. Metallo-beta lactamases (MBLs) was produced by 47.06% (8/17) of Pseudomonas aeruginosa and 62.96% (17/27) of Acinetobacter baumannii. CONCLUSION: The bacteriological approach for the management of VAP helps the clinicians in choosing the appropriate antibiotics. This study showed that quantitative cultures of endotracheal aspirate at a cutoff point of 10(5) cfu/ml is one of the alternative to bronchoscopy in the diagnosis of clinically suspected ventilator associated pneumonia.