Multicentre study of antimicrobial resistance and antibiotic consumption among 6,780 patients with bloodstream infections

Abstract

Several lines of evidence suggest there is a causal association between the use of antimicrobial agents and the prevalence of antimicrobial resistance in hospitalacquired bacterial pathogens [1, 2]. However, recently published works have indicated the magnitude of the association may be lower than that previously observed and that many other variables, such as patient factors may be responsible for the development of antimicrobial resistance [3, 4]. The specific goals of this study were (1) to estimate antimicrobial resistance rates for four epidemiologically important pathogens causing bloodstream infections (BSI), (2) to compare the antimicrobial resistance rates with the hospital’s antibiotic consumption data, and (3) to determine a possible relationship between the use of antimicrobial agents and the prevalence of drug resistance in these microorganisms. The participating hospitals were partners in the TREAT project, financed by the European Community (EC, 5th Framework, 1999) and focusing on the application of an electronic decision support system to reduce antimicrobial resistance in hospitalised patients [5] This multicentre study was conducted at Freiburg University Hospital, Freiburg, Germany; Rabin Medical Center, Tel Aviv (Petah Tiqva), Israel; Aalborg Hospital, Aalborg, Denmark; and Catholic University Hospital, Rome, Italy. Data on consumption of antibiotics (from 1998 to 2001) were supplied by the hospital pharmacies and expressed in daily defined doses (DDD) per 1,000 bed-days, as outlined by the World Health Organisation. Data on consumption of the following drugs were provided (if included in the local formulary): clindamycin, trimethoprim-sulfamethoxazole, imipenem, ampicillin, ceftazidime, cefepime, piperacillin, piperacillin-tazobactam, and gentamicin. We prospectively included, from 1998 to 2001, all consecutive non-repeat blood isolates of patients with nosocomial BSI according to the definition given by the Centers for Disease Control and Prevention (Atlanta, GA, USA). Mixed cultures were excluded. Selected isolates from patients with bacteraemia included Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. Microorganisms were identified using standard methods. Trends in resistance and the possible correlation between resistance and consumption were analysed using the logit regression line. Antimicrobial consumption patterns varied widely at the four sites. The most frequently prescribed drugs (>40 DDD per 1,000 bed-days) were ampicillin and gentamicin in Denmark and Israel and ceftazidime in Germany and Italy. Eur J Clin Microbiol Infect Dis (2006) 25:815–817 DOI 10.1007/s10096-006-0211-2