Both early-onset and late-onset ventilator-associated pneumonia are caused mainly by potentially multiresistant bacteria

Abstract

To compare the causative pathogens of early-onset and late-onset ventilator-associated pneumonia (VAP) diagnosed by bronchoalveolar lavage quantitative cultures. Most previous reports have been based on endotracheal aspirate cultures and gave uncertain findings. Prospective evaluation of consecutive patients with clinical suspicion for VAP. Multidisciplinary intensive care unit of a university hospital. During a 3-year period 473 patients with clinical suspicion of VAP entered the study. Diagnosis of VAP was confirmed by cultures of bronchoalveolar lavage (> 10(4) cfu/ml) specimens in 408 patients. Protected bronchoalveolar lavage samples were taken. Initial antibiotic therapy was modified upon bronchoalveolar lavage culture results. Among 408 patients 191 had early-onset (< 7 days mechanical ventilation) and 217 late-onset (> or = 7 days) VAP. Potentially multiresistant bacteria, mainly Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA), were the most commonly isolated pathogens in both types of VAP. No difference was noted in the contribution of potentially multiresistant pathogens (79% vs. 85%), P. aeruginosa (42% vs. 47%), or MRSA (33% vs. 30%) between early-onset and late-onset VAP. Initial antibiotic therapy was modified in 58% of early-onset VAP episodes and in 36% of late-onset VAP episodes. No difference in mortality was found between the two types of VAP. Both early-onset and late-onset VAP were mainly caused by potentially multiresistant bacteria, most commonly P. aeruginosa and MRSA. Antimicrobial agents against these pathogens should be prescribed empirically, at least in our institution.