Common PFGE patterns in antibiotic-resistant Enterococcus faecalis from humans and cheeses

A prospective laboratory-based surveillance of resistant Enterococcus faecalis isolates among patients at Besancon Hospital and other hospitals in the Franche-Comte region of France was initiated in 1995. Resistant E. faecalis screening was extended to cheeses. DNA fingerprints by pulsed-field gel electrophoresis of resistant E. faecalis from cheeses and clinical specimens were then compared in order to seek evidence of a common origin. All samples of each of the five varieties of cheeses contained high-level kanamycin resistant (HLKR) E. faecalis. Infection with E. faecalis occurred in 217 out of 9152 patients admitted during the study period giving a crude incidence estimated at 2.37%. One hundred and eighty-three E. faecalis clinical isolates (81.3%) expressed one or more mechanisms of acquired resistance and 106 isolates (47.1%) were HLKR. The rate of HLKR among isolates responsible for community-acquired infections (29/54) was not significantly different from that of isolates responsible for hospital-acquired infections (77/171). Two major epidemic DNA patterns including respectively 39 and 32 clinical isolates, predominantly HLKR, and resistant isolates from cheeses clustered in two clonal groups of patterns. These results were confirmed by combined-gel analysis of patterns obtained after macrorestriction with two enzymes used separately. Our study suggests that cheeses may serve as a reservoir of antibiotic-resistant Enterococcus with characteristics that allow it to persist and spread in the community. (C) 2000 Academic Press.