%0 Journal Article %A Cornelis, G. %T Distribution of β-Lactamases A and B in some Groups of Yersinia enterocolitica and their Role in Resistance %D 1975 %J Microbiology, %V 91 %N 2 %P 391-402 %@ 1465-2080 %R https://doi.org/10.1099/00221287-91-2-391 %I Microbiology Society, %X SUMMARY: Yersinia enterocolitica W222 (serological group 3) synthesized two different intracellular β-lactamases, called A and B. Enzyme B was more sensitive than A to inhibition by cloxacillin. The minimum inhibitory concentrations of various β-lactam antibiotics for strains of Y. enterocolitica of groups 3 and 9 and the effect of cloxacillin on these concentrations suggested differential roles for β-lactamases of types A and B in penicillin and cephalosporin resistance. Type B enzymes protected Y. enterocolitica against cephalothin and cephalosporin C, whereas type A enzymes protected very efficiently against carbenicillin. Protection against other β-lactam antibiotics was exerted by both enzymes. However, while both enzymes readily hydrolysed cephaloridine and showed no crypticity with this substrate, they only conferred a very weak protection against it. This may be because cephaloridine reached its target quickly, before it was degraded. The resistance of strains of Y. enterocolitica from groups 1, 2 and 16 was also explicable in terms of a two-enzyme system, whereas strains belonging to group 5b produced only a type B lactamase and were sensitive to carbenicillin. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-91-2-391