Rectal colonization with vancomycin-resistant enterococci among high-risk patients in an Israeli hospital.

The prevalence of rectal carriage of vancomycin-resistant enterococci (VRE) in two high-risk populations--61 patients admitted to ICU and 92 patients on renal dialysis--was studied longitudinally over a period of six months in a 650-bed general hospital. ICU patients were swabbed weekly and dialysis patients monthly. Enterococcal isolates were fully identified using the ATB identification system, and MICs were determined according to the NCCLS recommendations. Enterococci were isolated in 52 (83.6%) ICU patients and 86 (93.4%) dialysis patients. VRE were recovered at least once in 14 (27%) ICU patients and four (4.8%) dialysis patients. All VRE isolates (MIC of vancomycin > or = 256 micrograms/mL) were resistant to teicoplanin (MIC > or = 32 micrograms/mL; vanA phenotype), 87.5% were ampicillin-resistant, and 92% showed high-level resistance to gentamicin; 88% were E. faecium. The main risk factors for acquisition of VRE included duration of hospitalization in the six months preceding entry into the study and during the survey (P = 0.009 and 0.007 respectively, for ICU patients), and duration of antibiotic administration (P = 0.005, for ICU patients). The impact of vancomycin was most prominent (P = 0.005 for receipt and 0.06 for duration of administration, in ICU patients). Six of the 18 VRE carriers developed bacteraemia, six isolates being vancomycin-susceptible and one vancomycin-resistant (one patient had both). In this study, the first in Israel, a low rectal carriage rate occurred in renal dialysis patients and antibiotic use was the most important risk factor for VRE colonization.