Study of the in vitro activity of norfloxacin and other drugs on amoxicillin-resistant uropathogenic isolates.
The in vitro activity of a quinolinecarboxylic acid compound, norfloxacin, was compared with those of amikacin, carbenicillin, cefazolin, cefoxitin, gentamicin, nalidixic acid, and oxolinic acid against 243 Gram-positive and Gram-negative amoxicillin-resistant (MIC 800 greater than or equal to micrograms/ml) uropathogenic isolates. Norfloxacin showed remarkable activity against the majority of the bacteria tested. Ninety percent of strains of Staphylococcus aureus, Streptococcus faecalis, Citrobacter freundii and Serratia spp. were inhibited by 3.12 micrograms/ml or less. Among the Gram-negative urinary isolates, only a few Enterobacter, Escherichia coli, Klebsiella, Proteus and Pseudomonas aeruginosa strains required norfloxacin levels between 12.5 and 25 micrograms/ml. The MBC was within one dilution of the MIC for 100% of the Gram-positive strains and 95% of the Gram-negative isolates against norfloxacin and aminoglycosides. Norfloxacin had a markedly higher inhibitory index than all other antimicrobial agents for Gram-positive cocci and Gram-negative bacteria. From its in vitro activity, norfloxacin appears to be a potentially valuable agent for the treatment of serious urinary tract infections.
D000658:Amoxicillin / Q000494:pharmacology*; D000892:Anti-Infective Agents, Urinary / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D009643:Norfloxacin; D010403:Penicillin Resistance; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000382:microbiology*
D000892:Anti-Infective Agents, Urinary; D009268:Nalidixic Acid; D000658:Amoxicillin; D009643:Norfloxacin