In vitro activity of PD 117596-2, a broad-spectrum difluoroquinolone.
The activity of PD 117596-2, a novel quinolone, was compared to that of other quinolones, ceftazidime, imipenem and gentamicin. PD 117596-2 inhibited most Enterobacteriaceae at concentrations less than 0.25 micrograms/ml, being equal or superior in activity to ciprofloxacin and 2- to 4-fold more active than ofloxacin. It inhibited ceftazidime-resistant Enterobacter spp., Citrobacter spp. and Serratia marcescens. The MIC90 for Pseudomonas aeruginosa, including strains with imipenem MICs of 8 micrograms/ml and gentamicin MICs greater than 16 micrograms/ml, was 0.25 micrograms/ml. PD 117596-2 was more active than ciprofloxacin against Pseudomonas cepacia and Pseudomonas maltophilia, and it inhibited Neisseria gonorrhoeae and Haemophilus influenzae at less than 0.03 micrograms/ml. PD 117596-2 inhibited staphylococci at 0.5 micrograms/ml, being 2-fold superior to other quinolones, and with an MIC of 0.25 micrograms/ml was more active against group A, B, C and G streptococci and Streptococcus pneumoniae. MICs for Bacteroides spp. were 2 micrograms/ml compared to 8-32 micrograms/ml for other agents. The frequency of spontaneous resistance was low (less than 10(-10]. Differences in MICs and MBCs were within one dilution, and there was a minimal effect of inoculum size. Although PD 117596-2 was less active at pH 5.5, MICs were less than 0.5 micrograms/ml.
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Department of Medicine, College of Physicians & Surgeons, Columbia University, New York, New York 10032.
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D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D002442:Ceftazidime / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects*; D005839:Gentamicins / Q000494:pharmacology; D015378:Imipenem / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000494:pharmacology; D011549:Pseudomonas / Q000187:drug effects; D013210:Staphylococcus / Q000187:drug effects; D013291:Streptococcus / Q000187:drug effects
D000890:Anti-Infective Agents; D005839:Gentamicins; D002939:Ciprofloxacin; D015378:Imipenem; D002442:Ceftazidime; D015242:Ofloxacin