-Lactamases from Yersinia enterocolitica

Abstract

SUMMARYTwo P-lactamases, A and B, have been shown to be present in a strain of Yersinia enterocolitica (w222). P-Lactamase A hydrolyses a variety of penicillins and cephalosporins. This enzyme is sensitive to thiol reagents, is only partially inhibited by 0-1 mM-cloxacillin and has a molecular weight of approximately 20000. P-Lactamase B shows strong cephalosporinase activity but does not hydrolyse some of the penicillins. It is more resistant than P-lactamase A to thiol reagents, is completely inhibited by 0-1 mM-cloxacillin and has a molecular weight of about 34000. With cephaloridine as a substrate, which is readily hydrolysed by both enzymes, about 85 % of the total activity of a cell extract is due to P-lactamase A and 15 % to B.Addition of 6-aminopenicillanic acid to the culture during growth results in a 2-to 4-fold selective increase in the amount of P-lactamase B.Two P-lactamases similar to enzymes A and B have been found in five other strains of Y. enterocolitica. In contrast, only one p-lactamase, similar to enzyme B, has been detected in a different strain of Y. enterocolitica (~66), which is abnormal in that it is sensitive to ampicillin. Addition of 6-aminopenicillanic acid to cultures of this strain results in an 8-to 10-fold increase in p-lactamase production.

β-Lactamase expression in Yersinia enterocolitica biovars 1A, 1B and 3

“…This group con®rmed the latter view, ®nding a relationship between biovar and susceptibility to several â-lactam antibiotics (Table 1 and [22]). Furthermore, differences in the regulation and expression of BlaA and BlaB, the two chromosomal â-lactamases of Y. enterocolitica [24], were found among strains of biovars 2, 4 and 5 [25] and these data were related to biovar-speci®c susceptibilities to â-lactams. This report describes the extension of these studies to Y. enterocolitica strains of biovars 1A, 1B and 3.…”

“…Because BlaA and BlaB display characteristic inhibition pro®les [24,26], inhibition results were interpreted as follows. Where clavulanate inhibited activity completely, BlaA (class A) was deduced to be the sole â-lactamase; where aztreonam inhibited activity completely, BlaB (class C) was deduced to be the sole enzyme.…”

Cefoxitin Resistance to Beta-Lactamase: a Major Factor for Susceptibility of Bacteroides fragilis to the Antibiotic

“…Onishi and co-workers (17) tested 91 isolates, mainly members of the family Enterobacteriaceae, and were able to demonstrate &3lactamase activity against ce-foxitin by only seven cultures: three of Enterobacter sp., three ofEscherichia coli, and one of Klebsiella sp. Cefoxitin has also been demonstrated to be resistant to the &-lactamases of Yersinia enterocolitica (4).…”

Homology between virF, the transcriptional activator of the Yersinia virulence regulon, and AraC, the Escherichia coli arabinose operon regulator

“…Transconjugants were selected on MacConkey agar. Selective agents were nalidixic acid (35 ,ugIml), kanamycin (25 FgIml), and ampicillin (100 ,ug/ml to select pUC19, pTZ19R, or pSUP2O2 derivatives in E. coli; 300 ,uwg/ml to select the same plasmids in Y. enterocolitica [12] Fig. 2.…”