Association between antecedent intravenous antimicrobial exposure and isolation of vancomycin-resistant enterococci

Area of Science:

• Infectious Diseases
• Clinical Microbiology
• Hospital Epidemiology

Background:

• Vancomycin-resistant enterococci (VRE) are a significant cause of healthcare-associated infections.
• Understanding antimicrobial exposure risks is crucial for VRE prevention strategies.

Purpose of the Study:

• To evaluate the association between specific intravenous antimicrobial exposures and the isolation of VRE.
• To identify antimicrobial agents that predict VRE development or enterococcal colonization.

Main Methods:

• Case-control study design comparing VRE isolates to vancomycin-susceptible enterococci (VSE) and non-enterococci controls.
• Statistical analysis adjusted for time at risk, patient morbidity, and concurrent antimicrobial use.
• Evaluation of intravenous antimicrobial exposures including imipenem, ceftazidime, ampicillin, piperacillin, and vancomycin.

Main Results:

• Imipenem and ceftazidime were significant predictors of VRE compared to VSE controls.
• Ampicillin and imipenem were significantly associated with VRE compared to non-enterococci controls.
• Neither piperacillin nor vancomycin showed an association with VRE in either comparison.

Conclusions:

• Exposure to imipenem and ceftazidime increases the risk of VRE isolation.
• Ampicillin and imipenem are associated with VRE, suggesting a need for judicious use.
• Replacing broad-spectrum cephalosporins with extended-spectrum penicillins like piperacillin may be an effective strategy to reduce VRE.