Impact of inappropriate antimicrobial therapy on outcome in patients with hospital-acquired pneumonia caused by Acinetobacter baumannii

The purpose of this study was to evaluate the impact of inappropriate antimicrobial therapy on the outcome of patients with hospital-acquired pneumonia (HAP) caused by Acinetobacter baumannii.All cases of HAP caused by A. baumannii from January 2000 to March 2006 at the Samsung Medical Center (Seoul, Korea) were analyzed retrospectively.A total of 116 patients with clinically significant Acinetobacter HAP were enrolled. Among the A. baumannii isolates, 60.3% showed multi-drug resistance (MDR), 16.4% were found to have imipenem resistance, and 15.5% had pan-drug resistance (PDR). The mean APACHE II score of the patients was 22.3 +/- 7.9. The overall in-hospital and pneumonia-related mortality rates were 47.4% and 37.9%, respectively. The univariate analysis showed that the factors associated with pneumonia-related mortality were: MDR, PDR, high APACHE II score, inappropriate empirical antimicrobial therapy, and inappropriate definitive antimicrobial treatment (All p < 0.05). Among these, a high APACHE II score and inappropriate definitive antimicrobial therapy were found to be independent factors associated with a high mortality, after adjustment for other variables.The appropriate definitive antimicrobial therapy should be provided in patients with HAP caused by A. baumannii.