Impact of diversity of antibiotic use on the development of antimicrobial resistance

J Antimicrob Chemother. 2006 Jun;57(6):1197-204. doi: 10.1093/jac/dkl097. Epub 2006 Mar 24.

Abstract

Objectives: To evaluate the impact of different antibiotic strategies on acquisition of resistant microorganisms.

Methods: A prospective study was conducted over a 44 month period in a single ICU. Four empirical antibiotic strategies for ventilator-associated pneumonia (VAP) were sequentially implemented. Over the initial 10 months, patient-specific antibiotic therapy was prescribed; then, 4 month periods of prioritization or restriction rotation cycles of various antimicrobial agents were implemented for a total of 24 months; and, finally, during the last 10 months (mixing period) the first-line antibiotic for VAP was changed following a pre-established schedule to ensure maximum heterogeneity. Antibiotic consumption was closely monitored every month, and antimicrobial resistance patterns were regularly assessed. Antimicrobial heterogeneity was estimated using a modified Peterson index (AHI) measuring the ratios for the five most used antibiotics. Colonization by targeted microorganisms and susceptibility patterns were compared with the patient-specific period.

Results: Higher diversity of antibiotic prescription was obtained during patient-specific therapy (AHI = 0.93) or mixing periods (AHI = 0.95) than during prioritization (AHI = 0.70) or restriction periods (AHI = 0.68). High homogeneity was associated with increases in carbapenem-resistant Acinetobacter baumannii (CR-Ab) [relative risk (RR) 15.5; 95%CI 5.5-42.8], extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (RR 4.2; 95%CI 1.9-9.3) and Enterococcus faecalis (RR 1.7; 95%CI 1.1-2.9). During the restriction period, incidence of ESBL-producing Enterobacteriaceae and E. faecalis returned to patient-specific rates but CR-Ab remained higher.

Conclusions: Antibiotic prescription patterns balancing the use of different antimicrobials should be promoted to reduce the selection pressure that aids the development of resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter baumannii / drug effects
  • Acinetobacter baumannii / isolation & purification
  • Adult
  • Aged
  • Anti-Bacterial Agents / therapeutic use*
  • Drug Resistance, Bacterial*
  • Enterobacteriaceae / drug effects
  • Enterobacteriaceae / isolation & purification
  • Enterococcus faecalis / drug effects
  • Enterococcus faecalis / isolation & purification
  • Female
  • Humans
  • Intensive Care Units
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Pneumonia, Bacterial / prevention & control*
  • Prospective Studies
  • beta-Lactamases / analysis

Substances

  • Anti-Bacterial Agents
  • beta-Lactamases