In-vitro activity of pefloxacin compared to other antibiotics

Abstract

Pefloxacin is a new quinolone carboxylic acid with a broad spectrum of antibacterial activity. A comparison was made of the in-vitro activity of pefloxacin and that of nine other antibiotics (ampicillin, ticarcillin, piperacillin, cefazolin, cefotaxime, ceftazidime, gentamicin, amikacin and norfloxacin). The MIC ₉₀ of pefloxacin against 500 strains of Enterobacteriaceae ranged from 0.25 mg/1 ( Escherichia coli , indole + Proteus spp., Enterobacter cloacae, Salmonella spp. and Shigella spp.) to 1 mg/1 ( Klebsiella pneumoniae ). Pefloxacin inhibited 90% of 52 strains of Pseudomonas aeruginosa at 2.5 mg/1 (range 0.25 mg/1–4 mg/1). The MIC ₉₀ of pefloxacin against 100 Staphylococcus aureus strains (78 oxacillin resistant strains) was 0.4 mg/1 (range 0.12–0.5 mg/1). It was markedly less active against Streptococcus faecalis and Str. pneumoniae (37 strains of each species) the MIC ₉₀ being 4 mg/1 against both species. Overall, pefloxacin was at least as active as the third-generation cephalosporins against Enterobacteriaceae and was more active than any other antibiotic tested against P. aeruginosa, S. epidermidis , and S. aureus . Against E. coli , pefloxacin had a more rapid anti-bacterial activity than piperacillin. A paradoxical effect was observed with pefloxacin. An optimal killing rate was observed at concentrations of pefloxacin compatible with those one can expect in blood of patients treated with this drug.