In vitro activity of various antimicrobial agents against Staphylococcus aureus isolates including fluoroquinolone- and oxacillin-resistant strains.
To determine susceptibility to 31 old and new antimicrobials, 44 strains of Staphylococcus aureus, most resistant to oxacillin and ciprofloxacin and isolated in a community hospital, were tested in vitro. For the peptide/peptide-derivative compounds, with the exception of mersacidin, all strains were inhibited by less than or equal to 2 micrograms/ml. Minimum inhibitory concentration (MIC)90 values indicated mupirocin, teicoplanin, and MDL 62211 to be fourfold more active than vancomycin, ramoplanin, and decaplanin. For fluoroquinolones, ciprofloxacin-resistant S. aureus exhibited high-level cross-resistance to ofloxacin, norfloxacin, fleroxacin, enoxacin, and Ro 23-9424. WIN 57253, a new fluorinated naphthyridine, showed good activity against these strains. Among the beta-lactams, the penem-derivative compounds (imipenem, meropenem, FCE 22101, and HRE 664) had the greatest activity, although resistance to each compound was detected among oxacillin-resistant S. aureus. The presence of tazobactam reduced the piperacillin MIC90 fourfold. Oxacillin-susceptible strains were susceptible to cephalosporins/cephamycins, whereas most oxacillin-resistant strains exhibited resistance. This study has shown that certain old and new quinolones and peptide-derivative compounds have good in vitro activity against multiply resistant strains of S. aureus.
Aldridge
K E
KE
Louisiana State University Medical Center, New Orleans 70112.
Jones
R N
RN
Barry
A L
AL
Gelfand
M S
MS
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology; D010397:Penicillanic Acid / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*; D000078142:Tazobactam
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D010397:Penicillanic Acid; D000078142:Tazobactam; D010068:Oxacillin