EFFECT OF THE COMBINATION OF VANCOMYCIN AND BACTERIOCIN AGAINST VANCOMYCIN-RESISTANT Enterococcus (VRE)

Enterococcus sp are opportunistic pathogens recognized for causing serious hospital infections, their resistance to glycopeptides such as vancomycin, decreases therapeutic alternatives and increases mortality rates. A new option to this problem is the combination of bacteriocins with antimicrobials. Currently, the synergistic actions between bacteriocins and antimicrobials have been studied aiming to reduce the concentration of antibiotics necessary to eliminate a certain target pathogen, to potentiate its action, as well as to reduce the side effects. Therefore, the objective of this work was to evaluate a potential synergistic action between bacteriocin and vancomycin antimicrobials in vancomycin-resistant enterococci (VRE). For this, 6 strains of Enterococcus sp were used, 5 isolates of clinical origin, vancomycin resistance profile, and 1 milk isolate, already proven to produce bacteriocin (enterocin). The study of the interaction between enterocin and vancomycin was performed by the checkerboard methodology. In a microtiter plate were aliquoted into the columns, different concentrations for vancomycin, and in the lines, different concentrations of enterocin. For vancomycin, an initial concentration of 256 μg / mL was used, followed by a serial dilution to the concentration of 4 μg / mL. The enterocin was diluted 1: 2 to 1: 256. Subsequently, 100 μL of the inoculum of the VRE bacteria, adjusted to 108 CFU / mL, was added to each well. One column was filled with inoculum of the VRE bacteria and the concentrated enterocine; another containing inoculum and concentrated vancomycin; and a column with inoculum adjusted only, in order to establish control for the measurement of the results. The incubation was at 37ºC for 24 hours, and a UFC test was performed to measure the result. In 100% of the cases there was decrease of 1Log in bacterial growth after association enterocin / drug. In 60% of the cases the reduction can be observed in the concentration of 16 μg / mL vancomycin. And 40% at the concentration of 32 μg / mL. In 80% of the cases there was a decrease in bacterial growth in the presence of the 1: 256 dilution of enterocin. In this way, our results showed a reduction in cellular concentration when applied to the enterocin / drug combination, and this combination made it possible to decrease the vancomycin concentration, making it more tolerable to a clinical application according to the parameters of vancocinemia.