Alternativas terapéuticas para revertir la multirresistencia mediada por bombas de eflujo

Abstract

The central objective was to restore the antimicrobial susceptibility in vitro, in strains of Escherichia coli with multidrug resistance phenotype (MDR), from commercial farms by combining antimicrobials with the efflux pump inhibitor 1-(1-naphthylmethyl)-piperazine (NMP). Strains were isolated from the faeces of production and companion animals and from septic tanks. Sensibility profiles were tested to the isolations and 10 MDR strains were obtained. Laboratory strains included two isogenic mutants: AG100A, an RND type pumpdeficient strain and AG112, an acrAB overexpressing strain) and a wild-type strain, AG100. The minimum inhibitory concentrations (MICs) of florfenicol, ciprofloxacin, tetracycline and ampicillin were determined by a serial microdilution method in Luria Bertani (LB) broth in presence or absence of NMP. The highest percentages of resistance were for tetracycline and ampicillin. All combinations of multidrug resistance included tetracycline in their profile. Ampicillin had no effect when combining to NMP. In most of the E. coli MDR strains and in AG112, MICs of ciprofloxacin, florfenicol and tetracycline decreased ≥ 4-fold with NMP. There was no relevant change against wild type strain and MIC remained the same against AG100, independently of NMP´s concentrations. Tetracycline resistance strains strains are probably able to become multirresistant. Ciprofloxacin, tetracycline and florfenicol demonstrated be efflux pumps substrates, but not ampicillin. It is promising the combination of NMP with florfenicol.