Estrategias para la implementación y reporte de los puntos de corte CLSI vigentes y pruebas fenotípicas confirmatorias para BLEE y carbapenemasas en bacilos Gram negativos en laboratorios clínicos de Colombia

In 2010, the Clinical and Laboratory Standards Institute (CLSI) began a process to revise and update the breakpoints for broth microdilution and disk diffusion for cephalosporins (Cefazolin, Cefotaxime, Ceftriaxone, Ceftazidime), monobactams (Aztreonam) and carbapenems (Imipenem, Meropenem, Ertapenem and Doripenem). The changes made were based on PK/PD models that attempt to predict clinical outcomes using minimum inhibitory concentration (MIC) and specific dosage regimens, regardless of the resistance mechanism expressed by the organism. The new breakpoints would eliminate the need to perform screening and confirmatory testing for ESBLs and carbapenemases for treatment decisions, and thus they would be used only for infection control purposes. Nevertheless, there are limitations to current methods in Colombia, a lack of knowledge regarding the recent changes and epidemiologic alarm over new B-lactamases spreading in our country. Therefore it was necessary to formulate and issue recommendations for clinical laboratories, with the aim of standardizing the criteria for reports on antibiograms in Gram-negative bacilli, including the current CLSI breakpoints and applying phenotypic confirmatory testing to detect ESBLs and Carbapenemases.