Transferable vanB2 Tn 5382 -Containing Elements in Fecal Streptococcal Strains from Veal Calves

Abstract

ABSTRACT Three vancomycin-resistant veal calf fecal streptococci, identified as Streptococcus gallolyticus ( n = 2) and Streptococcus lutetiensis , were shown to harbor vanB2 Tn 5382 -like elements earlier described in enterococci. One S. gallolyticus strain had a 1,495-bp IS 256 -related element inserted in vanS B . The vanB2 Tn 5382 element present in the plasmid-free S. lutetiensis strain was transferable to Enterococcus faecium BM4105-RF, Enterococcus faecalis JH2-2, and its recombination-deficient derivative, UV202. The transfer frequencies were comparable between recipient strains (from 1 × 10 −7 to 7 × 10 −6 ). All transconjugants acquired a vanB -containing chromosomal insert of approximately 100 kb, apparently by site-specific integration. Secondary transconjugants were not observed in intraspecies retransfer experiments. These observations are consistent with a conjugative, selftransmissible, integrative element that might be involved in the interspecies spread of vanB2 resistance determinants. Two JH2-2-derived transconjugants had also gained additional copies of large vanB -containing chromosomal fragments, a process that involves unexplained mechanisms that seems to require functional host cell-dependent recombination mechanisms.