title: Physiological and molecular analysis of a mecA-negative Staphylococcus aureus clinical strain that expresses heterogeneous methicillin resistance.
abstract: Staphylococcus aureus clinical isolate 61/5896 exhibited methicillin resistance (MIC 64 mg/L), but lacked mecA, which encodes penicillin-binding protein 2'. The strain was isolated in England in 1961, and exhibited unstable heterogeneous methicillin resistance. When cultivated in drug-free medium, the methicillin resistance of 61/5896 increased after three daily passages, then decreased and was completely lost after 12 days' passage. Electron microscopy revealed that strain 61/5896 had a thicker and rougher cell wall than its methicillin-susceptible derivatives. It produced about three times more penicillin-binding protein 2 (PBP2) than methicillin-susceptible derivatives. The strain was characteristically a non-producer of autolytic enzyme, though the phenotype, which was lost easily, was not directly correlated with methicillin resistance.
authors.affiliation: Department of Bacteriology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Yoshida
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kuwahara-Arai
authors.forename: Tadashi
authors.initials: T
authors.lastname: Baba
authors.forename: Longzhu
authors.initials: L
authors.lastname: Cui
authors.forename: Judith F
authors.initials: JF
authors.lastname: Richardson
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramatsu
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001329:Autolysis; D001426:Bacterial Proteins; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics*; D002473:Cell Wall / Q000648:ultrastructure; D006602:Hexosyltransferases; D017403:In Situ Hybridization; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008854:Microscopy, Electron; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics*; D046915:Penicillin-Binding Proteins; D010405:Penicillinase / Q000235:genetics / Q000378:metabolism; D010406:Penicillins / Q000494:pharmacology; D010458:Peptidyl Transferases; D010957:Plasmids; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000648:ultrastructure; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D010405:Penicillinase; D001618:beta-Lactamases; D008712:Methicillin; D000117:Acetylglucosamine