Molecular analysis of vanA enterococci isolated from humans and animals innortheastern Italy

A total of 53 vancomycin-resistant vanA-positive enterococci isolates from poultry farms (17 Enterococcus faecium; 8 Enterococcus durans) and from dif ferent hospitals (23 E. faecium; 5 Enterococcus faecalis) in northeastern I taly were compared on the basis of their antibiotic susceptibilities, their SmaI pulsed-field gel electrophoresis (PFGE) patterns, and the organizatio n of their Tn1546-related elements. Ampicillin resistance was similar in bo th groups of isolates (52 and 60.7%, respectively), whereas human strains w ere more resistant to high-level gentamicin and streptomycin. A total of 52 % of animal strains and 60% of human strains were resistant to tetracycline , and 56% and 46.4% to quinupristin/dalfopristin, respectively. In E. faeci um and E. durans animal isolates, nine and six distinct PFGE patterns, resp ectively, were found: in two instances indistinguishable isolates were foun d from different farms. In E. faecium and E. faecalis human isolates, nine and six distinct PFGE patterns, respectively, were, found; among E.,faecium strains, 12 were identical or closely related and were isolates from the s ame hospital. Elements mediating vanA-glycopeptide resistance were characte rized by PCR with primers that amplified 10 overlapping fragments of Tn1546 . A total of 84.6% of animal strains and 64.2% of human strains contained e lements indistinguishable from the prototype Tn1546. In addition, nine diff erent types were identified, but none was common to animal and human strain s.