ABSTRACT
In the early papers, several authors reported that antibiotics that belong to the β-lactam group have little or no activity against Yersinia enterocolitica, there is indeed a striking difference between Y. enterocolitica and Y. pseudotuberculosis in their sensitivity to β-lactam antibiotics. Members of serological groups of Y. enterocolitica are resistant to benzylpenicillin and cephalothin and most of the groups also to ampicillin and carbenicillin. Nearly all the strains of Y. enterocolitica that belong to serotype O:3 are highly resistant to carbenicillin. β-Lactamases A and B from Y. enterocolitica are cell-bound and are released only when the cells are subjected to some form of lysis. Isoelectric focusing allows one to determine and to compare the isoelectric points of β-lactamases with great accuracy and extreme sensitivity. Several authors showed that Y. enterocolitica could also act as a recipient for resistance plasmids. As might be expected, resistance factors were subsequently detected in Y. enterocolitica strains isolated in 1970.
