Consejo Nacional de Investigaciones Científicas y Tecnológicas, CONICET, Buenos Aires, Argentina.
Department of Pharmacology, Facultad de Ciencias Veterrinarias, Universidad Nacional de La Plata, 60 y 118 CC 296, 1900 La Plata, Buenos Aires, Argentina.
J Med Microbiol. 2012 Jun;61(Pt 6):786-792. doi: 10.1099/jmm.0.040204-0. Epub 2012 Feb 16.
The objective of this study was to evaluate the interaction of the efflux pump inhibitor 1-(1-naphthylmethyl)-piperazine (NMP) when combined with different families of antimicrobial agents against isogenic strains and multidrug-resistant (MDR) Escherichia coli field strains isolated from animals. Laboratory isogenic strains of E. coli with different levels of expression of efflux pumps were used as quality controls. Ten MDR E. coli strains were collected from healthy animals in a cross-sectional study in four commercial dairy farms. The MICs of florfenicol, ciprofloxacin, tetracycline and ampicillin were determined by a serial microdilution method in Luria-Bertani broth in the presence or absence of NMP. NMP used with ampicillin exerted no effect on the isogenic or field strains. In most of the field MDRE. coli strains and in an acrAB-overexpressing (AG112) isogenic strain, the MICs of florfenicol, ciprofloxacin and tetracycline decreased at least fourfold when the antimicrobial was combined with the highest NMP concentrations. In the wild-type strain (AG100), there were no decreases of more than twice the MIC, whilst in strain AG100A, an efflux pump-deficient strain, the MIC did not change, regardless of the concentration of NMP used with these three antimicrobials. Thus, ampicillin was not affected by the efflux pump mechanism, whereas ciprofloxacin, tetracycline and florfenicol were shown to be substrates of efflux pumps, with a consequent significant reduction in MICs. Resistance could not be completely reversed in the E. coli field strains by NMP, probably because other resistance mechanisms were also present. However, in strain AG112, the MIC results demonstrated that NMP expressed an important synergistic activity with florfenicol. The reduction in florfenicol MIC value was sufficient to reverse antimicrobial resistance completely for AG112.
本研究旨在评估外排泵抑制剂 1-(1-萘基甲基)-哌嗪（NMP）与不同抗菌药物家族联合使用时对具有不同外排泵表达水平的同种异源大肠杆菌实验室菌株和从动物中分离的多药耐药（MDR）大肠杆菌田间菌株的相互作用。使用具有不同外排泵表达水平的同种异源大肠杆菌实验室菌株作为质量控制。从四个商业奶牛场的横断面研究中，从健康动物中收集了 10 株 MDR 大肠杆菌。通过在 Luria-Bertani 肉汤中进行连续微量稀释法，在存在或不存在 NMP 的情况下，测定氟苯尼考、环丙沙星、四环素和氨苄西林的 MIC。NMP 与氨苄西林联合使用对同种异源或田间菌株均无影响。在大多数 MDR 大肠杆菌田间株和过表达 acrAB（AG112）的同种异源菌株中，当抗菌药物与最高 NMP 浓度联合使用时，氟苯尼考、环丙沙星和四环素的 MIC 至少降低了四倍。在野生型菌株（AG100）中，MIC 没有增加两倍以上，而在缺乏外排泵的菌株 AG100A 中，无论使用 NMP 的浓度如何，MIC 均未发生变化。因此，氨苄西林不受外排泵机制的影响，而环丙沙星、四环素和氟苯尼考被证明是外排泵的底物，导致 MIC 显著降低。NMP 不能完全逆转大肠杆菌田间株的耐药性，可能是因为还存在其他耐药机制。然而，在 AG112 菌株中，MIC 结果表明 NMP 与氟苯尼考具有重要的协同作用。氟苯尼考 MIC 值的降低足以完全逆转 AG112 的抗菌耐药性。
