AUTHOR=Pina-Vaz Cidália , Silva Ana P. , Faria-Ramos Isabel , Teixeira-Santos Rita , Moura Daniel , Vieira Tatiana F. , Sousa Sérgio F. , Costa-de-Oliveira Sofia , Cantón Rafael , Rodrigues Acácio G. 

TITLE=A Flow Cytometric and Computational Approaches to Carbapenems Affinity to the Different Types of Carbapenemases

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 7 - 2016

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01259

DOI=10.3389/fmicb.2016.01259

ISSN=1664-302X

ABSTRACT=The synergy of carbapenem combinations regarding Enterobacteriaceae producing different types of carbapenemases was study through different approaches: flow cytometry and computa-tional analysis. Ten well characterized Enterobacteriaceae (KPC, verona integron-encoded metallo-β-lactamases –VIM and OXA-48-like enzymes) were selected for the study. The cells were incubated with a combination of ertapenem with imipenem, meropenem or doripenem and killing kinetic curves performed with and without reinforments of the drugs. A cephalosporin was also used in combination with ertapenem. A flow cytometric assay with DiBAC4-(3), a membrane potential dye, was developed in order to evaluate the cellular lesion after 2 h incuba-tion. A chemical computational study was performed to understand the affinity of the different drugs to the different types of enzymes. Flow cytometric analysis and time-kill assays showed a synergic effect against KPC and OXA-48 producing-bacteria with all combinations; only ertapenem with imipenem was synergic against VIM producing-bacteria. A bactericidal effect was observed in OXA-48-like enzymes. Ceftazidime plus ertapenem was synergic against ESBL-negative KPC producing-bacteria. Ertapenem had the highest affinity for those enzymes according to chemical computational study. The synergic effect between ertapenem and others carbapenems against different carbapenemase-producing bacteria, representing a therapeutic choice, was described for the first time.  Easier and faster laboratorial methods for car-bapenemase characterization are urgently needed. The design of an ertapenem derivative with similar affinity to carbapenemases but exhibiting more stable bonds was demonstrated as highly desirable.