VENTILATOR-ASSOCIATED PNEUMONIA CAUSED BY POTENTIALLY DRUG-RESISTANT BACTERIA

To determine risk factors for ventilator-associated pneumonia (VAP) ca used by potentially drug-resistant bacteria such as methicillin-resist ant Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter bauma nnii, and/or Stenotrophomonas maltophilia, 135 consecutive episodes of VAP observed in a single ICU over a 25-mo period were prospectively s tudied. For all patients, VAP was diagnosed based on results of bronch oscopic protected specimen brush (greater than or equal to 10(3) cfu/m l) and bronchoalveolar lavage (greater than or equal to 10(4) cfu/ml) specimens. Seventy-seven episodes were caused by ''potentially resista nt'' bacteria and 58 episodes were caused by ''other'' organisms. Acco rding to logistic regression analysis, three variables among potential factors remained significant: duration of mechanical ventilation (MV) greater than or equal to 7 d (odds ratio [OR] = 6.0), prior antibioti c use (OR = 13.5), and prior use of broad-spectrum drugs (third-genera tion cephalosporin, fluoroquinolone, and/or imipenem) (OR = 4.1). Dist ribution of the 245 causative bacteria was analyzed according to four groups defined by prior duration of MV (< 7 or greater than or equal t o 7 d) and prior use or lack of use (within 15 d) of antibiotics. Alth ough 22 episodes of early-onset VAP in patients receiving no prior ant ibiotics were caused by antibiotic-susceptible bacteria, 84 episodes o f late-onset VAP in patients receiving prior antibiotics were mainly c aused by potentially resistant bacteria. Differences in the potential efficacies (ranging from 100% to 11%) against microorganisms of 15 ant imicrobial regimens were studied according to classification into thes e four groups. These findings may provide a more rational basis for se lecting the initial therapy of patients suspected of having VAP.