Emergence of vancomycin-resistant enterococci in New York City

Area of Science:

• Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Enterococci are a significant cause of hospital-acquired infections.
• These bacteria possess intrinsic antimicrobial resistance and can acquire new resistance mechanisms.
• Vancomycin-resistant enterococci (VRE) have been identified in clusters of nosocomial infections since 1988.

Purpose of the Study:

• To identify the clinical and epidemiological characteristics of VRE infections.
• To investigate the antimicrobial susceptibility of VRE isolates.
• To determine the molecular basis for the spread of vancomycin resistance.

Main Methods:

• Retrospective analysis of clinical and epidemiological data from 361 VRE patients.
• Antimicrobial susceptibility testing of VRE isolates.
• Molecular analyses including restriction enzyme analysis and DNA-DNA hybridization with the vanA gene probe.

Main Results:

• VRE cases increased significantly in New York City from 1989 to 1991, involving 38 hospitals.
• The majority of VRE infections (98%) were nosocomially acquired, with 83% of patients having recent vancomycin/cephalosporin exposure.
• Of 23 tested isolates, 19 (83%) were resistant to all tested antimicrobials.
• Molecular analyses identified four vanA probing patterns and 14 distinct strains, suggesting a mobile genetic element is responsible for resistance spread.

Conclusions:

• VRE has emerged as a rapidly spreading pathogen in New York City healthcare settings.
• The rapid dissemination of vancomycin resistance is likely mediated by highly mobile genetic elements, such as transposons.
• VRE poses a significant challenge due to its resistance to multiple antimicrobials.