RESUMEN
BACKGROUND: A high proportion of currently isolated gram-negative bacilli are resistant to beta-lactams by producing beta-lactamases. beta-lactam and beta-lactamase inhibitor combinations have been successfully used to overcome the resistance. In this study, in vitro antimicrobial activity of a new combination, cefatrizine-clavulanic acid, was determined against gram-negative bacilli isolated from community-acquired urinary track infections. METHODS: Nonduplicate strains of Enterobacteriaceae, isolated in 2003 from urine specimens of outpatients and inpatients of less than 3 hospital days at Severance Hospital, were tested by the NCCLS agar dilution method. RESULTS: Of a total of 204 isolates, 144 (71%) were Escherichia coli and 30 (15%) were Klebsiella spp. MIC50 and MIC90 of cefatrizine for E. coli were 2 microgram/mL and 16 microgram/mL, respectively. MIC90s of both cefaclor and cefoxitin were also 16 g/mL. MIC50 and MIC90 of cefatrizine-clavulanic acid for E. coli were 1 microgram/mL and 4 microgram/mL, respectively, which were 1/2-1/4 of those of cefaclor and cefoxitin. For Klebsiella spp., MIC90 of cefatrizine was 4 microgram/mL with an MIC range of 1->128 microgram/mL, whereas that of cefatrizine-clavulanic acid was 2 microgram/mL with an MIC range of 0.5-32 microgram/mL. In vitro activity of cefatrizine-clavulanic acid was higher than that of cefatrizine. CONCLUSIONS: Improved in vitro activity of cefatrizine-clavulanic acid against isolates of E. coli and Klebsiella spp. from community-acquired urinary track infection suggested that the combination is useful for an empirical treatment of the infection.