title: In vitro activity of Ro 13-9904, a new beta-lactamase-stable cephalosporin.
abstract: The minimal inhibitory concentration (MIC) of Ro 13-9904 against 245 clinical isolates was determined by an agar dilution method. The activity of Ro 13-9904 against most Enterobacteriaceae was similar to that of cefotaxime; it was slightly more active than cefotaxime against Proteus mirabilis, Providencia species, and Serratia marcescens, but slightly less active against Klebsiella species. Ro 13-9904 was twofold more active than cefotaxime and threefold more active than ticarcillin against ticarcillin-susceptible Pseudomonas aeruginosa, with a mean MIC of 7.2 micrograms/ml; isolates highly resistant to ticarcillin were inhibited by a mean MIC of 17.2 micrograms/ml. Ro 13-9904 was fourfold more active than ampicillin against susceptible Haemophilus influenzae and was equally active against beta-lactamase-producing isolates. Ro 13-9904 was highly active against pneumococci and moderately active (MIC, 4 micrograms/ml) against Staphylococcus aureus isolates, whether they were susceptible or resistant to penicillin G. Oxacillin-resistant S. aureus and Streptococcus faecalis were completely resistant to Ro 13-9904 (MIC, greater than 128 micrograms/ml).
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D002439:Cefotaxime / Q000031:analogs & derivatives* / Q000494:pharmacology; D002443:Ceftriaxone; D006801:Humans; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D002443:Ceftriaxone; D001618:beta-Lactamases; D002439:Cefotaxime