Kinetics of Sulbactam Hydrolysis by ?-Lactamases, and Kinetics of ?-Lactamase Inhibition by Sulbactam.

ABSTRACT: Sulbactam is one of four ?-lactamase inhibitors in current clinical use to counteract drug resistance caused by degradation of ?-lactam antibiotics by these bacterial enzymes. As a ?-lactam itself, sulbactam is susceptible to degradation by ?-lactamases. I investigated the Michaelis-Menten kinetics of sulbactam hydrolysis by 14 ?-lactamases, representing clinically widespread groups within all four Ambler classes, i.e., CTX-M-15, KPC-2, SHV-5, and TEM-1 for class A; IMP-1, NDM-1, and VIM-1 for class B; Acinetobacter baumannii ADC-7, Pseudomonas aeruginosa AmpC, and Enterobacter cloacae P99 for class C; and OXA-10, OXA-23, OXA-24, and OXA-48 for class D. All of the ?-lactamases were able to hydrolyze sulbactam, although they varied widely in their kinetic constants for the reaction, even within each class. I also investigated the inactivation kinetics of the inhibition of these enzymes by sulbactam. The class A ?-lactamases varied widely in their susceptibility to inhibition, the class C and D enzymes were very weakly inhibited, and the class B enzymes were essentially or completely unaffected. In addition, we measured the sulbactam turnover number, the sulbactam/enzyme molar ratio required for complete inhibition of each enzyme. Class C enzymes had the lowest turnover numbers, class A enzymes varied widely, and class D enzymes had very high turnover numbers. These results are valuable for understanding which ?-lactamases ought to be well inhibited by sulbactam. Moreover, since sulbactam has intrinsic antibacterial activity against Acinetobacter species pathogens, these results contribute to understanding ?-lactamase-mediated sulbactam resistance in Acinetobacter, especially due to the action of the widespread class D enzymes.

SUBMITTER: Shapiro AB 

PROVIDER: S-EPMC5700308 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature