Binding affinities of β-lactam antibodies for penicillin-binding protein 2' in methicillin-resistant staphylococcus aureus

Yoshihiro Sumita, Masatomo Fukasawa, Susumu Mitsuhashi, Matsuhisa Inoue

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We devised an accurate procedure with which to measure the affinities of β-lactam antibiotics for penicillin-binding protein (PBP) 2' in methicillin-resistant Staphylococ-cus aureus (MRSA). In the present study, we usedtwo isogenic strains of MRSA, one heterogeneous and the other homogeneous, derived from the methicillin-susceptible strainFDA209P, harbouring the mecA gene. In these MRSA strains, PBP2' was saturated by [14C]benzylpenicillin (PCG) at a concentration of 300 mg/L. In addition, the saturation of PBP2' by [14C]PCG required anincubation period of 30 min. According to these results, the precise affinities of β-lactam antibiotics for PBP2' were determined by the 'accurate competition assay', using a high concentration of [14C]PCG and extending the reaction time. This procedure yielded lower IC50 values of β-lactams than the 'usual competition assay'. However, each β-lactam had almost the same affinity for PBP2' in heterogeneous and homogeneous strains. These results suggest there is a factor(s) other than PBP2' responsible for controlling resistance levels and the heterogeneity or homogeneity of MRSA strains.

Original languageEnglish
Pages (from-to)473-481
Number of pages9
JournalJournal of Antimicrobial Chemotherapy
Volume35
Issue number4
DOIs
Publication statusPublished - Apr 1 1995

ASJC Scopus subject areas

  • Pharmacology
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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