Transferable vanB2 Tn5382-containing elements in fecal streptococcal strains from veal calves

Three vancomycin-resistant veal calf fecal streptococci, identified as Streptococcus gallolyticus (n = 2) and Streptococcus lutetiensis, were shown to harbor vanB2 Tn5382-like elements earlier described in enterococci. One S. gallolyticus strain had a 1,495-bp IS256-related element inserted in vanS(B). The vanB2 Tn5382 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 x 10(-7) to 7 x 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.