Antimicrobial susceptibility of strains of Enterobacteriaceae isolated from bloodstream infections using current CLSI and EUCAST breakpoints

Abstract

Understanding local susceptibility patterns is important when selecting antimicrobials for initial empirical antibiotic-therapy of bloodstream infections. Because the determination of susceptibility is dependent on the breakpoints used, the aim of the study was to compare the antimicrobial susceptibility results to different classes of antibiotics of 512 strains of Enterobacteriaceae (200 ESβL positive) isolated from bloodstream using CLSI 2013 and current EUCAST 2013 guidelines to evaluate the impact of breakpoint discrepancies. The results of the study showed that statistically significant discrepancies (p ≤ 0.001) were found for amoxicillin/clavulanic acid, piperacillin alone or with tazobactam, imipenem, meropenem, cefepime (only ESβL negative isolates), amikacin and gentamicin using current CLSI or EUCAST interpretive criteria. Further harmonization of CLSI and EUCAST breakpoints is warranted.