Susceptibility to first-generation cephalosporins in Enterobacteriaceae isolated from urine culture according to CLSI and EUCAST breakpoints

Abstract

Currently, the use of cefazolin is recommended to determine the susceptibility to first-generation oral cephalosporins in strains of enterobacteria in uncomplicated UTI. We determined susceptibility differences to oral cephalosporins in urinary strains according to cefazolin or cefalotin breakpoints and the correlation of susceptibility between cefazolin and cefadroxil. We studied 52 strains with cefalotin and cefazolin by disk-diffusion and MIC (Kirby-Bauer and Vitek XL) and a subgroup by disk-diffusion for cefadroxil. Agreement among different methods was 100% for K. pneumoniae and Proteus spp. In Escherichia coli, agreement for Vitek and disk-diffusion were 0 and 50% respectively. Susceptibility to first generation cephalosporins in E. coli should be determined with cefazolin. Agreement between cefazolin and cefadroxil suggests that cefazolin could also predict the susceptibility of cefadroxil.