Abstract
A total of 53 vancomycin-resistant
vanA
-positive enterococci isolates from poultry farms (17
Enterococcus faecium
; 8
Enterococcus durans
) and from different hospitals (23
E. faecium
;
5
Enterococcus faecalis
) in northeastern Italy were compared on the basis of their antibiotic susceptibilities, their
Sma
I pulsed-field gel electrophoresis (PFGE) patterns, and the organization
of their Tn
1546
-related elements. Ampicillin resistance was similar in both groups of isolates (52 and 60.7%, respectively), whereas human strains were 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. faecium
and
E. durans
animal isolates, nine and six distinct PFGE patterns, respectively, were found: in two instances indistinguishable isolates were found 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 same hospital. Elements mediating
vanA
-glycopeptide resistance were characterized by PCR with primers that amplified 10 overlapping fragments of Tn
1546
. A total of 84.6% of animal strains and 64.2% of human strains contained
elements indistinguishable from the prototype Tn
1546
. In addition, nine different types were identified, but none was common to animal and human strains.