In vitro antimicrobial activity of RU-59863, a C-7 catechol substituted cephalosporin.
The in vitro activity of RU-59863, a so-called "fifth generation" catechol cephalosporin, was evaluated against 606 bacterial isolates and compared with the activities of cefotaxime, ceftazidime, cefepime, and cefpirome. RU-59863 demonstrated a broad spectrum of inhibition and superior overall activity than comparators when tested against Enterobacteriaciae (MIC90s, 0.015 to 2 micrograms/ml), Pseudomonas aeruginosa (MIC90, 0.5 microgram/ml), Stenotrophomonas maltophilia (MIC90, 0.25 microgram/ml), Acinetobacter ssp. (MIC90, 4 micrograms/ml), and oxacillin-susceptible Staphylococcus ssp. (MIC90s, 0.5 to 8 micrograms/ml). Potent RU-59863 activity was also observed against beta-haemolytic and viridans gr. streptococci (MIC90s, 0.12-0.5 microgram/ml), Streptococcus pneumoniae (MIC90s, 0.03 to 0.5 microgram/ml), Haemophilus influenzae (MIC90, 0.06 microgram/ml), and Neisseria gonorrhoeae (MIC90, 0.06 micrograms/ml). RU-59863 demonstrated marginal potency against Enterococcus faecalis (MICs 2 to 16 micrograms/ml) and was inactive against Enterococcus faecium (MIC90, > 128 micrograms/ml). Oxacillin-resistant staphylococci were not inhibited by RU-59863 (MIC90s, 32 to 128 micrograms/ml). Among the cephalosporins tested, RU-59863 performed best versus ceftazidime-resistant Bush group 1 isolates and strains producing extended spectrum beta-lactamases. RU-59863 was also effective against many fluoroquinolone-, aminoglycoside-, and imipenem-resistant isolates. RU-59863 seems to be a significant advance in cephalosporin chemistry and activity, especially against Gram-negative pathogens resistant to current beta-lactam therapeutic agents. Further studies of human pharmacokinetics and against clinical infections are encouraged.
Erwin
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ME
Department of Pathology, University of Iowa College of Medicine, Iowa City 52242, USA.
Varnam
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Jones
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D001419:Bacteria / Q000187:drug effects*; D002511:Cephalosporins / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests
D002511:Cephalosporins; C107662:RU 59863