ABSTRACT
Twenty-three strains of Staphylococcus aureus with borderline resistance to oxacillin were studied. These strains were not detected by the cefoxitin test, tests for penicillin-binding protein 2a (PBP2a), mecA, and mecA(LGA251) were negative, and the strains were genetically unrelated. To detect all strains resistant to oxacillin, laboratories should routinely test for both cefoxitin and oxacillin.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Methicillin-Resistant Staphylococcus aureus/drug effects , Oxacillin/pharmacology , Staphylococcal Infections/microbiology , Bacterial Proteins/genetics , Cefoxitin/pharmacology , Cluster Analysis , Electrophoresis, Gel, Pulsed-Field , Humans , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests/methods , Molecular Epidemiology , Molecular Typing , Penicillin-Binding Proteins/genetics , Staphylococcal Infections/epidemiology , Tunisia/epidemiologyABSTRACT
Activity of rifampin against 129 Streptococcus mitis isolates obtained from patients with hematologic cancer was investigated. One hundred twenty-five strains were susceptible to rifampin, and 4 were resistant (MIC = 32 to 64 microg/ml). Resistance to rifampin was related to mutations in the rpoB gene: His(526)Asn in three strains and His(526)Asp in one strain.
