Differential Correlation Between Rates of Antimicrobial Drug Consumption and Prevalence of Antimicrobial Resistance in a Tertiary Care Hospital in Greece

Abstract

To investigate whether there is a correlation between the rates of antimicrobial drug consumption in hospital departments and the prevalence of antimicrobial resistance among clinically important bacteria recovered in the hospital. Retrospective study. Tertiary care hospital in Greece. Data on antimicrobial consumption (from January 2001 through December 2004) were expressed as defined daily doses per 100 bed-days. The prevalence of antimicrobial resistance among isolates of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterococcus faecium recovered during the same time period were calculated by the microbiology department. We then performed the following analyses: (1) a comparison of the consumption rates for different antimicrobial groups in individual hospital departments, (2) a comparison of the prevalence of resistance to different antimicrobials, and (3) a correlation analysis of antimicrobial consumption rates and the prevalence of antimicrobial resistance. The rates of antimicrobial consumption and the prevalence of resistance varied substantially among the hospital's departments. The annual rate of consumption for carbapenems correlated with the rate of consumption for glycopeptides and third-generation cephalosporins (P < .05). Among P. aeruginosa isolates, the prevalence of imipenem resistance correlated with the prevalence of resistance to amikacin, ciprofloxacin, and ceftazidime (P < .05). The rate of carbapenem consumption correlated with the prevalence of imipenem resistance among P. aeruginosa and A. baumannii isolates (P < .05). The rate of aminoglycoside consumption correlated with the prevalence of amikacin resistance among P. aeruginosa, K. pneumoniae, and E. coli isolates (P < .05). However, the rate of consumption for fluoroquinolones and glycopeptides had no correlation with the prevalence of ciprofloxacin resistance among gram-negative bacteria or vancomycin resistance among E. faecium isolates. These data are suggestive of a differential relationship between antimicrobial consumption and the prevalence of antimicrobial resistance among various species and for various antimicrobial agents. These findings may help to optimize antimicrobial prescription policies in the hospital, especially in departments that have both high rates of antimicrobial consumption and a high prevalence of antimicrobial resistance.