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 ini-tial empirical antibiotic-therapy of bloodstream infections. Because the determination of sus-ceptibility is dependent on the breakpoints used, the aim of the study was to compare the antimi-crobial susceptibility results to different classes of antibiotics of 512 strains of Enterobacteria-ceae (200 ESβL positive) isolated from blood-stream using CLSI 2013 and current EUCAST 2013 guidelines to evaluate the impact of break- point discrepancies. The results of the study showed that statistically significant discrepan-cies (p ≤ 0.001) were found for amoxicillin/cla- vulanic acid, piperacillin alone or with tazobac- tam, imipenem, meropenem, cefepime (only ESβL negative isolates), amikacin and gentami- cin using current CLSI or EUCAST interpretive criteria. Further harmonization of CLSI and EUCAST breakpoints is warranted. This study could give useful information to physicians for managing bloodstream infections caused by Enterobacteriaceae.