Delgado-Valverde, MercedesValiente-Mendez, AdoracionTorres, EvaAlmirante, BenitoGomez-Zorrilla, SilviaBorrell, NuriaAller-Garcia, Ana IsabelGurgui, MercedesAlmela, ManelSanz, MercedesBou, GermanMartinez-Martinez, LuisCanton, RafaelAntonio Lepe, JoseCausse, ManuelGutierrez-Gutierrez, BelenPascual, AlvaroRodriguez-Baño, Jesus2023-01-252023-01-252016-12-02Delgado-Valverde M, Valiente-Mendez A, Torres E, Almirante B, Gómez-Zorrilla S, Borrell N, et al. MIC of amoxicillin/clavulanate according to CLSI and EUCAST: discrepancies and clinical impact in patients with bloodstream infections due to Enterobacteriaceae. J Antimicrob Chemother. 2017 May 1;72(5):1478-1487http://hdl.handle.net/10668/10780To compare results of amoxicillin/clavulanate susceptibility testing using CLSI and EUCAST methodologies and to evaluate their impact on outcome in patients with bacteraemia caused by Enterobacteriaceae. A prospective observational cohort study was conducted in 13 Spanish hospitals. Patients with bacteraemia due to Enterobacteriaceae who received empirical intravenous amoxicillin/clavulanate treatment for at least 48 h were included. MICs were determined following CLSI and EUCAST recommendations. Outcome variables were: failure at the end of treatment with amoxicillin/clavulanate (FEAMC); failure at day 21; and 30 day mortality. Classification and regression tree (CART) analysis and logistic regression were performed. Overall, 264 episodes were included; the urinary tract was the most common source (64.7%) and Escherichia coli the most frequent pathogen (76.5%). Fifty-two isolates (19.7%) showed resistance according to CLSI and 141 (53.4%) according to EUCAST. The kappa index for the concordance between the results of both committees was only 0.24. EUCAST-derived, but not CLSI-derived, MICs were associated with failure when considered as continuous variables. CART analysis suggested a 'resistance' breakpoint of > 8/4 mg/L for CLSI-derived MICs; it predicted FEAMC in adjusted analysis (OR = 1.96; 95% CI: 0.98-3.90). Isolates with EUCAST-derived MICs >16/2 mg/L independently predicted FEAMC (OR = 2.10; 95% CI: 1.05-4.21) and failure at day 21 (OR= 3.01; 95% CI: 0.93-9.67). MICs >32/2 mg/L were only predictive of failure among patients with bacteraemia from urinary or biliary tract sources. CLSI and EUCAST methodologies showed low agreement for determining the MIC of amoxicillin/clavulanate. EUCAST-derived MICs seemed more predictive of failure than CLSI-derived ones. EUCAST-derived MICs >16/2 mg/L were independently associated with therapeutic failure.enÁrea de Gestión Sanitaria Sur de SevillaAmoxicillin-potassium clavulanate combinationAnti-bacterial agentsBacteremiaEnterobacteriaceaeAgedAged, 80 and overEnterobacteriaceae infectionsEscherichia coliEscherichia coli infectionsFemaleHumansMaleMicrobial sensitivity testsMiddle agedProspective studiesbeta-lactamase inhibitorsresearch article28093484open accessEstudios prospectivosInfecciones por EnterobacteriaceaeInfecciones por Escherichia coliInhibidores de beta-lactamasasPruebas de sensibilidad microbiana10.1093/jac/dkw5621460-2091https://academic.oup.com/jac/article-pdf/72/5/1478/13703338/dkw562.pdf