Comparison of glycopeptide-resistant Enterococcus faecium isolates and glycopeptide resistance genes of human and animal origins

One hundred thirty-two glycopeptide-resistant Enterococcus faecium (GREF) i solates from different hospitals and pig and poultry farms in Belgium were compared on the basis of (i) their antibiotic susceptibilities, (ii) their SmaI pulsed-field gel electrophoresis (PFGE) patterns, and (iii) the organi zation of their Tn1546 or related elements in order to detect possible phen otypic and genotypic relationships among both groups of isolates. Human and animal vanA-positive GREF isolates were found to have similar susceptibili ty patterns; they remained susceptible to gentamicin and were, in general, susceptible to ampicillin. PFGE demonstrated a very high degree of genomic heterogeneity in both groups of isolates, However, indistinguishable isolat es were found within different farms or hospitals, and in two instances, ep idemiologically unrelated pig and human isolates showed indistinguishable P FGE patterns. In total, eight different transposon types were identified, a nd all were related to the prototype transposon Tn1546, The two predominant types, Tn1546 and type 2 transposons, which differed at three band positio ns, were present in both human and animal isolates, Type 2 transposons were significantly associated with pig isolates. The other types were seldom de tected. These data suggest a possible exchange of glycopeptide resistance m arkers between animals and humans.