Comparison of in vitro activity of cefepime against fresh clinical isolates and isolates 10 years ago

Abstract

The antibacterial activity of cefepime, cefozopran, cefpirome, ceftazidime, cefotaxime, piperacillin, and imipenem/cilastatin against clinical isolates in 1996-98 were tested (a total of 523 strains from 19 organism groups, i.e., methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, Citrobacter freundii, Enterobacter cloacae, Enterobacter aerogenes, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Serratia marcescens Pseudomonas aeruginosa, Burkholderia cepacia, Acinetobacter spp. and Bacteroides spp.) and compared to those against clinical isolates in 1985-87, prior to cefepime use. Staphylococci were uniformly susceptible (MIC₉₀, ≤0.025-3.13μg/mL) to all drugs except ceftazidime (MIC₉₀, 12.5μg/mL). This did not change in 1985-87. Among E. coli and K pneumoniae, the ranking of antibacterial activity was cefepime>cefpirome=cefozopran>imipenem/cilastatin>ceftazidime>piperacillin. Isolates of 13.3% of C. freundii and 16.7%of E. cloacae resistant to ceftazidime (13.3, 16.7% resistance respectibility) remained susceptible to cefepime and imipenem/cilastatin. Imipenem and fourth-generation cephalosporin were stable to β-lactamase produced from these species. P. aeruginosa isolates were susceptible to cefepime, cefozopran, ceftazidime and imipenem/cilastatin. Metalloenzyme was identified in 1 strain of S. marcescense. No difference in the antibacterial activity of cefepime to most species of bacteria was seen between this study and that 10 years ago. Cefepime thus has a low rate of selection in drug resistance because it has potent antibacterial activity and is stable to β-lactamase. Our results suggest that cefepime is useful in the treatment of bacterial infections. An extended-spectrum β-lactamase was identified in 2 strains from 82E. coli strains isolated from the same clinical center and showed the same pulsed-field gel electrophoresis (PFGE) pattern. It was surmised that the same clone had spread throughout the hospital.