Investigation of oxacillin-hydrolyzing beta-lactamase in borderline methicillin-resistant clinical isolates of Staphylococcus aureus

Zsuzsanna Gál, Péter Kovács, Ferenc Hernádi, György Barabás, László Kiss, Attila Iglói, István Szabó

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Background: Mechanisms of borderline resistance of Staphylococcus aureus to penicillinase-resistant penicillins (PRPs) may include hyperproduction of classical penicillinase and/or production of β-lactamase hydrolyzing also PRPs. Methods: β-Lactamase activity of whole cells and purified enzymes was estimated spectrophotometrically and in isolated cytoplasmic membranes by bioassay with Bacillus subtilis as test strain. Results: Out of 53 clinical isolates of S. aureus, 18 showed oxacillin MIC values from 0.5 to 2 μg/ml, which were reduced by sulbactam and/or clavulanic acid in the case of four isolates producing large quantities of inducible, type A β-lactamase. Cytoplasmic membranes isolated from these strains showed oxacillin-hydrolyzing activity. One of these strains was grown also in the presence of globomycin, an antibiotic known to interfere with the anchorage of membrane lipoproteins; this treatment eliminated the oxacillin-hydrolyzing activity. Conclusions: The resistance in these strains was due to a membrane-bound lipoprotein with oxacillin-hydrolyzing activity.

Original languageEnglish
Pages (from-to)233-238
Number of pages6
JournalCHEMOTHERAPY
Volume47
Issue number4
DOIs
Publication statusPublished - Jul 9 2001

Keywords

  • Methicillin resistance
  • Staphylococcus aureus
  • β-Lactamase

ASJC Scopus subject areas

  • Oncology
  • Pharmacology
  • Drug Discovery
  • Pharmacology (medical)
  • Infectious Diseases

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