In vitro activity of cefditoren: antimicrobial efficacy against major respiratory pathogens from Asian countries

In this study we evaluated the in vitro activities of cefditoren and 14 other comparator agents against 1025 isolates of major respiratory tract pathogens including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae and Staphylococcus aureus. Bacterial isolates were collected from 11 Asian countries. The majority of S. pneumoniae isolates (98.8%) were susceptible to cefditoren. The MIC50 and MIC90 values (minimum inhibitory concentrations for 50% and 90% of the organisms, respectively) of S. pneumoniae were ≤0.06 μg/mL and 1 μg/mL, respectively. These values were 2–32-fold lower than those of the other cephalosporins. Activity against S. pneumoniae was observed irrespective of penicillin or macrolide resistance. Cefditoren was also active against methicillin-susceptible S. aureus (100% susceptible; MIC90 = 1 μg/mL), H. influenzae (100% susceptible; MIC90 ≤ 0.016 μg/mL) and M. catarrhalis (MIC90 = 0.016 μg/mL). However, the cefditoren MIC90 of K. pneumoniae reached only 64 μg/mL (81.4% susceptible), which may be due to the high incidence of extended-spectrum β-lactamases in Asian countries. Therefore, cefditoren should be considered as a therapeutic option for the treatment of respiratory tract infections in Asian countries.