Effect of beta-lactamase on minimum inhibitory concentrations of methicillin in methicillin-resistant Staphylococcus aureus.
A study was undertaken to determine whether the production of penicillin-binding protein-2' (PBP-2') and the production of beta-lactamase were related to the minimum inhibitory concentrations of methicillin (DMPPC) in various strains of methicillin-resistant Staphylococcus aureus. The amount of PBP-2' produced by the low-level resistant strain L20A was small and the strain became resistant to DMPPC as a result of inactivation of DMPPC by beta-lactamase. The largest amount of PBP-2' produced was in a moderately resistant strain L21A but the MIC was not high since the strain was not capable of producing beta-lactamase and the population of cells was heterogeneous. The amount of PBP-2' produced in the high-level resistant strain L457A was lower than that in strain L21A but the MIC was high as a result of the production of beta-lactamase. Production of PBP-2' was essential for resistance to methicillin but production of beta-lactamase had a major effect on the MIC.
Sasatsu
M
M
Department of Microbiology, Tokyo College of Pharmacy, Japan.
Miyazawa
K
K
Noguchi
N
N
Kono
M
M
D001426:Bacterial Proteins; D002352:Carrier Proteins; D006602:Hexosyltransferases / Q000378:metabolism*; D008712:Methicillin / Q000494:pharmacology*; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D009097:Multienzyme Complexes / Q000378:metabolism*; D002267:Muramoylpentapeptide Carboxypeptidase; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases / Q000378:metabolism*; D013045:Species Specificity; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D001618:beta-Lactamases / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D009097:Multienzyme Complexes; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D001618:beta-Lactamases; D008712:Methicillin