Antimicrobial activity and disk diffusion susceptibility testing of Ro 40-6890, the active metabolite of the new cephalosporin ester, Ro 41-3399.
Ro 40-6890, the active metabolite of Ro 41-3399, was tested against 391 gram-negative and gram-positive clinical isolates. Ro 40-6890 was active against members of the family Enterobacteriaceae, Moraxella catarrhalis, pneumococci, other Streptococcus spp., and methicillin-susceptible staphylococci. Preliminary disk diffusion interpretive zone criteria were calculated for 5-, 10-, and 30-micrograms Ro 40-6890 disks and several possible MIC susceptibility breakpoints. We recommend the use of the 5-micrograms disk and suggest that the following zone diameters be used as breakpoints in clinical trials: susceptible, > or = 21 mm (MIC, < or = 1 microgram/ml); intermediate, 18 to 20 mm (MIC, 2 micrograms/ml); and resistant, < or = 17 mm (MIC, > or = 4 micrograms/ml).
Oregon Health Sciences University, Portland 97201.
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Pfaller
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Barry
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Fuchs
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D002511:Cephalosporins / Q000493:pharmacokinetics / Q000494:pharmacology*; D005658:Fungi / Q000187:drug effects*; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D002511:Cephalosporins; C079140:Ro 413399; C077918:Ro 406890