Departamento de Bioquímica, Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense Madrid, Madrid, Spain.
J Antimicrob Chemother. 2015 Jan;70(1):71-4. doi: 10.1093/jac/dku320. Epub 2014 Aug 21.
To detect the occurrence of low susceptibility to colistin (polymyxin E), a last-resort antimicrobial, among enterobacteria isolated from samples of animal origin (poultry and swine) and to find out the molecular basis of colistin resistance.
Salmonella enterica and Escherichia coli were isolated from eggs and swine samples. Bacterial strains were screened for colistin resistance by using MIC determinations interpreted according to EUCAST recommendations. pmrAB genes were amplified by PCR from bacterial isolates and their sequences were characterized.
Nine colistin-resistant strains were detected in a collection of 739 enterobacteria (S. enterica and E. coli) isolated from animal samples taken in different environments. Sequences encoding the PmrAB two-component sensor-regulator from two colistin-resistant E. coli strains isolated from swine faeces presented three non-synonymous polymorphisms, producing the variants 39S → I and 81R → S of PmrA and 161V → G of PmrB, among which the involvement of mutations in PmrA-81 and PmrB-161 in resistance to the antimicrobial had been previously shown. No variation at the protein level was detected after analysis of PmrAB sequences from seven colistin-resistant S. enterica strains.
E. coli strains carrying mutations in PmrAB that confer resistance to polymyxins, which might have evolved in vivo and have been rarely detected, are described for the first time in enterobacteria isolated from animals.
检测源于动物源性样本（家禽和猪）的肠杆菌科细菌对黏菌素（多黏菌素 E）这种最后手段抗菌药物的低敏感性的发生情况，并确定黏菌素耐药的分子基础。
从鸡蛋和猪的样本中分离出肠道沙门氏菌和大肠埃希菌。采用 MIC 测定法根据 EUCAST 建议来筛选对黏菌素有耐药性的细菌菌株。通过 PCR 从细菌分离株中扩增 pmrAB 基因，并对其序列进行了特征描述。
在从不同环境中采集的 739 株肠杆菌（肠道沙门氏菌和大肠埃希菌）的样本中，检测到 9 株耐黏菌素的菌株。从猪粪便中分离出的两株耐黏菌素的大肠埃希菌的 PmrAB 两组分传感器-调节剂的编码序列存在 3 个非同义突变，导致 PmrA 的 39S→I 和 81R→S 以及 PmrB 的 161V→G 变异，先前已经表明这些变异与该抗菌药物的耐药性有关。在对 7 株耐黏菌素的肠道沙门氏菌的 PmrAB 序列进行分析后，未检测到蛋白质水平的变化。
首次在从动物分离的肠杆菌中描述了携带 PmrAB 突变的大肠埃希菌菌株，这些突变赋予了对黏菌素的耐药性，这些突变可能是在体内进化而来的，且很少被检测到。
