Biochemical characteristics of a carbapenemase from an Acinetobacter baumannii isolate collected in Buenos Aires, Argentina

J Antimicrob Chemother. 1999 Jan;43(1):127-31. doi: 10.1093/jac/43.1.127.


Three carbapenem-resistant Acinetobacter baumannii isolates were collected at a hospital in Buenos Aires, Argentina. Isoelectric focusing revealed multiple beta-lactamases, with two of the isolates showing identical profiles. A pI 6.9 carbapenemase with a molecular weight of 30 kDa was purified from one of these two isolates. The enzyme was predominantly a penicillinase, with its highest Vmax for oxacillin but highest Vmax/Km for benzylpenicillin. First-generation cephalosporins and imipenem were weaker substrates than penicillins, and oxyimino-aminothiazolyl cephalosporins were essentially stable. Meropenem-hydrolysing activity was not detected, despite resistance. The carbapenemase was inhibited by clavulanic acid and tazobactam, but not by EDTA. These kinetics place the enzyme into functional group 2; as an oxacillinase it could be placed in sub-group 2d or, as a zinc-independent carbapenemase, in sub-group 2f.

MeSH terms

  • Acinetobacter / drug effects
  • Acinetobacter / enzymology*
  • Acinetobacter / isolation & purification
  • Argentina
  • Bacterial Proteins*
  • Carbapenems
  • Humans
  • Imipenem / metabolism
  • Imipenem / pharmacology
  • Isoelectric Focusing
  • Meropenem
  • Microbial Sensitivity Tests
  • Molecular Weight
  • Species Specificity
  • Sputum / microbiology
  • Thienamycins / metabolism
  • Thienamycins / pharmacology
  • Urine / microbiology
  • beta-Lactam Resistance / genetics
  • beta-Lactamases / chemistry*
  • beta-Lactamases / drug effects
  • beta-Lactamases / metabolism*


  • Bacterial Proteins
  • Carbapenems
  • Thienamycins
  • Imipenem
  • beta-Lactamases
  • carbapenemase
  • Meropenem