Background: Cefroxadine is an oral first-generation cephalosporin, which has been used for several years. But, the susceptibility data of cefroxadine were rarely reported in Korea. The current study attempted to determine the antibacterial activity of cefroxadine against the major clinical isolates.

Methods: According to the NCCLS recommendations, antibacterial activities of cefroxadine were measured against total 500 major clinical isolates. MICs were determined by the agar dilution method, a series of doubling dilutions from 128 to 0.03μg /mL, on Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, Proteus mirabilis, and Staphylococcus spp. In case of Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis, broth microdilution method, a series of doubling dilutions from 16 to 0.015μg /mL, was performed.

Results: Cefroxadine had variable activity against Enterobacteriaceae. MIC cumulative curves showed that cefroxadine had relatively low MIC distributions against E. coli, K. pneumoniae and P. mirabilis, showing MIC₅₀ were 4, 4, and 8μg/mL, respectively. Against E. cloacae, C. freundii, and S. marcescens, cefroxadine’s MIC₅₀ values ranged from 128 to >128μg /mL. For clinical isolates of methicillin-susceptible Staphylococcus aureus and methicillin-susceptible Staphylococcus epidermidis, cefroxadine had MIC₉₀ values were 4μg /mL and 8μg /mL, respectively. Cefroxadine had MIC₅₀ values of 1 μg/mL and >16μg /mL for penicillin-susceptible and penicillin-not-susceptible strains of S. pneumoniae, respectively. Cefroxadine had MIC₅₀ values of 8μg /mL and 4 μg/mL against H. influenzae and M. catarrhalis, respectively.

Conclusion: Cefroxadine had good activity against gram-positive bacteria, except penicillinresistant S. pneumoniae, and showed moderate antimicrobial activity against M. catarrhalis, E. coli, P. mirabilis, and K. pneumonaie. Cefroxadine had variable activity against Enterobacteriaceae other than the above-mentioned species. (Korean J Clin Microbiol 2003;6(1):37-40)