title: In vitro activity of cefotiam against oxacillin-resistant Staphylococcus epidermidis strains--reevaluation of beta-lactam antibiotics efficiency on MRSE.
abstract: We evaluated the efficacy of cefotiam (CTM) against Staphylococcus epidermidis (S. epidermidis) isolated from blood culture and central venous catheters. Of the S. epidermidis strains tested, 82.3% were methicillin (MPIPC)-resistant (MPIPC MIC > or = 0.5 microg/ml) and expressed the mecA gene, and 89.2% of these MPIPC-resistant S. epidermidis (MRSE) showed less than 8.0 microg/ml CTM MIC. In vitro killing kinetics of CTM against MRSE demonstrated that strains with high CTM MIC (> or = 4.0 microg/ml) showed high MPIPC MIC (> or = 4.0 microg/ml). All strains with low CTM MIC (< or = 2.0 microg/ml) showed MPIPC MIC lower than 2.0 microg/ml. In time-kill studies, CTM had high bactericidal activity against strains with low CTM MIC (< or = 2.0 microg/ml), regardless of whether they were mecA positive. These results demonstrated that MRSE isolates with low CTM MIC (< or = 2.0 microg/ml) are not easily induced CTM resistance by CTM treatment in vitro, and indicated the possibility that beta-lactams such as CTM could be an effective antibiotic agents against beta-lactam-sensitive MRSE infections.
authors.affiliation: Clinical Laboratory, Juntendo University Hospital, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nakamura
authors.forename: Toyoko
authors.initials: T
authors.lastname: Oguri
authors.forename: Shigeki
authors.initials: S
authors.lastname: Misawa
authors.forename: Yoko
authors.initials: Y
authors.lastname: Tabe
authors.forename: Sigemi
authors.initials: S
authors.lastname: Kondo
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miyake
authors.forename: Noriko
authors.initials: N
authors.lastname: Miyake
authors.forename: Jun
authors.initials: J
authors.lastname: Igari
authors.forename: Akimichi
authors.initials: A
authors.lastname: Ohsaka
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015310:Cefotiam / Q000494:pharmacology*; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology*; D010403:Penicillin Resistance; D013212:Staphylococcus epidermidis / Q000187:drug effects*; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D015310:Cefotiam; D010068:Oxacillin