In Vitro Antimicrobial Activity of Cefditoren pivoxil, an Oral Cephalosporin, against Major Clinical Isolates

ABSTRACT

BACKGROUND: Cefditoren is an oral cephalosporin with excellent activity against Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis, which are the predominant bacterial causes of community-acquired respiratory tract infections. The current study attempted to determine the antibacterial activity of cefditoren against the major clinical isolates. METHODS: According to the NCCLS recommendations, antibacterial activities of cefditoren were measured against total 504 major clinical isolates. MICs were determined by the agar dilution method, a series of doubling dilutions from 128 to 0.03 microgram/mL, on E. coli, K. pneumoniae, E. cloacae, C. freundii, S. marcescens, P. mirabilis, and Staphylococcus spp. In case of H. influenzae, S. pneumoniae, and M. catarrhalis, broth microdilution method, a series of doubling dilutions from 16 to 0.015 microgram/mL, was performed. RESULTS: Cefditoren had variable activity against Enterobacteriaceae. MIC cumulative curves showed that cefditoren had low MIC distributions against E. coli and P. mirabilis, and MIC90 were 8 and 0.5 microgram/mL, respectively. Against K. pneumoniae, E. cloacae, C. freundii, and S. marcescens, cefditoren's MIC90 values ranged from 32 to >128 microgram/mL. For clinical isolates of methicillin-susceptible S. aureus and methicillin-susceptible S. epidermidis, cefditoren had MIC90 values of 1 microgram/mL and 0.5 microgram/mL, respectively. Cefditoren had MIC90 values of 1 microgram/mL for penicillin-susceptible and penicillin-not-susceptible strains of S. pneumoniae. Cefditoren had MIC90 values of 0.03 microgram/mL and 0.5microgram/mL against H. influenzae and M. catarrhalis, respectively. CONCLUSION: Cefditoren had excellent activity against S. pneumoniae, H. influenzae, and M. catarrhalis. Cefditoren had variable activity against Enterobacteriaceae. The results of this study confirm the excellent activity of cefditoren against the major respiratory tract pathogens and suggest that cefditoren could be a good antibiotic for empiric oral treatment of community-acquired respiratory tract infections.