Prevalence of vancomycin-resistant enterococci in fecal samples from hospitalized patients and nonhospitalized controls in a cattle-rearing area of France

Abstract

Vancomycin-resistant enterococci (VRE) have emerged as nosocomial pathogens over the last decade, but little is known about their epidemiology. We report on the prevalence of VRE fecal colonization on the basis of a prospective study among patients hospitalized in a hematology intensive care unit and among nonhospitalized subjects living in the local community. A total of 243 rectal swabs from hematology patients and 169 stool samples from the control group were inoculated onto bile-esculin agar plates with and without 6 mg of vancomycin per liter and into an enrichment bile-esculin broth supplemented with 4 mg of vancomycin per liter. A total of 37% of the hospitalized patients and 11.8% of the subjects from the community were found to be VRE carriers. A total of 65 VRE strains were isolated: 12 (18.5%) E. faecium, 46 (70.7%) E. gallinarum, and 7 (10.8%) E. casseliflavus strains. No E. faecalis strains were detected. All the E. faecium strains were of the vanA genotype. Molecular typing by pulsed-field gel electrophoresis revealed a different pattern for each vanA VRE strain that originated from an individual subject. To our knowledge, this is the first study to be carried out in a cattle-rearing region of France. It reports a higher VRE prevalence than that reported in previous European or U.S. studies. A partial explanation is the use of an enrichment broth step which enabled detection of strains which would otherwise have been missed, but the fact that subjects and patients were recruited from a predominantly agricultural area where vancomycin-related antibiotics have recently been used in animal husbandry could also contribute to the high levels of VRE in patients and subjects alike.

FIG. 1

SmaI restriction endonuclease patterns obtained by PFGE for VanA strains. Lanes 1 and 14, PFGE I marker; lane 2, patient 1 (control group); lanes 3, 4, and 5, patient 2 (hematology unit); lane 6, patient 3 (hematology unit); lanes 7 and 8, patient 4 (hematology unit); lane 9, patient 5 (control group); lane 10, patient 6 (control group); lane 11, patient 7 (hematology unit); lane 12, patient 8 (hematology unit); lane 13, patient 9 (hematology unit).