Oxacillin-hydrolyzing beta-lactamase involved in resistance to imipenem in Acinetobacter baumannii

FEMS Microbiol Lett. 1997 Aug 15;153(2):333-9. doi: 10.1111/j.1574-6968.1997.tb12593.x.

Abstract

Acinetobacter baumannii strain A148, a clinical isolate resistant to imipenem (MIC = 32 mg l-1), synthesized two beta-lactamases with pIs 6.3 and > 9.2. The pI 6.3 enzyme hydrolyzed the penicillins, including isoxazoylpenicillins, first-, second- and, to a lesser extent, third-generation cephalosporins. It was inhibited by chloride ions and by the penem beta-lactamase inhibitor BRL 42715. Clavulanate was a weak inhibitor and EDTA did not affect the beta-lactamase activity. This enzyme also hydrolyzed imipenem with a catalytic efficiency (Kcat/Km) of 1500 mM-1 s-1. Moreover, this purified beta-lactamase produced a positive microbiological clover-leaf test with imipenem. Therefore, the pI 6.3 beta-lactamase was considered to be involved in the imipenem resistance of A. baumannii strain A148.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter / drug effects*
  • Acinetobacter / enzymology
  • Anti-Bacterial Agents / pharmacology
  • Cephalosporins / metabolism
  • Enzyme Inhibitors / pharmacology
  • Hydrolysis
  • Imipenem / pharmacology*
  • Isoelectric Point
  • Kinetics
  • Lactams*
  • Molecular Weight
  • Oxacillin / metabolism*
  • Penicillins / metabolism
  • Sodium Chloride / pharmacology
  • Substrate Specificity
  • Thienamycins / pharmacology*
  • beta-Lactam Resistance / physiology*
  • beta-Lactamase Inhibitors
  • beta-Lactamases / chemistry
  • beta-Lactamases / isolation & purification
  • beta-Lactamases / metabolism*
  • beta-Lactams*

Substances

  • Anti-Bacterial Agents
  • Cephalosporins
  • Enzyme Inhibitors
  • Lactams
  • Penicillins
  • Thienamycins
  • beta-Lactamase Inhibitors
  • beta-Lactams
  • C6-(N1-methyl-1,2,3-trazolylmethylene)penem
  • Sodium Chloride
  • Imipenem
  • beta-Lactamases
  • Oxacillin