Wasyl Dariusz, Hoszowski Andrzej, Zając Magdalena
Department of Microbiology, National Reference Laboratory for Salmonellosis and Antimicrobial Resistance, National Veterinary Research Institute, Partyzantów 57, 24-100 Puławy, Poland.
Department of Microbiology, National Reference Laboratory for Salmonellosis and Antimicrobial Resistance, National Veterinary Research Institute, Partyzantów 57, 24-100 Puławy, Poland.
Vet Microbiol. 2014 Jul 16;171(3-4):307-14. doi: 10.1016/j.vetmic.2014.01.040. Epub 2014 Feb 15.
The study was focused on characterisation of quinolone resistance mechanisms in Salmonella isolated from animals, food, and feed between 2008 and 2011. Testing of Minimal Inhibitory Concentrations revealed 6.4% of 2680 isolates conferring ciprofloxacin resistance. Simultaneously 37.7% and 40.8% were accounted for, respectively, nalidixic acid and ciprofloxacin Non Wild-Type populations. Amplification and sequencing of quinolone resistance determining region of topoisomerases genes in 44 isolates identified multiple amino-acid substitutions in gyrA at positions Ser83 (N=22; → Leu, → Phe, → Tyr), Asp87 (N=22; → Asn, → Gly, → Tyr) and parC (Thr57Ser, N=23; Ala141Ser, N=1). No relevant mutations were identified in gyrB and parE. Twelve patterns combining one or two substitutions were related to neither serovar nor ciprofloxacin MIC. In 92 isolates suspected for plasmid mediated quinolone resistance two qnr alleles were found: qnrS1 (or qnrS3; N=50) and qnrB19 (or qnrB10; N=24). Additionally, two isolates with chromosomally encoded mechanisms carried qnrS1 and qnrS2. All tested isolates were negative for qnrA, qnrC, qnrD, qepA, aac(6')-Ib-cr. Both chromosomal and plasmid mediated quinolone resistance determinants were found in several Salmonella serovars and Pulsed Field Gel Electrophoresis was used to assess phylogenetic similarity of selected isolates (N=82). Salmonella Newport was found to accumulate quinolone resistance determinants and the serovar was spreading clonally with either variable gyrA mutations, qnrS1/S3, or qnrB10/B19. Alternatively, various determinants are dispersed among related S. Enteritidis isolates. Antimicrobial selection pressure, multiple resistance determinants and scenarios for their acquisition and spread make extremely difficult to combat quinolone resistance.
该研究聚焦于2008年至2011年间从动物、食品和饲料中分离出的沙门氏菌对喹诺酮类药物的耐药机制。最低抑菌浓度测试显示，2680株分离菌中有6.4%对环丙沙星耐药。同时，分别有37.7%和40.8%的菌株对萘啶酸和环丙沙星呈非野生型群体。对44株分离菌的拓扑异构酶基因喹诺酮耐药决定区进行扩增和测序，发现在gyrA基因的Ser83位点（N = 22；→Leu、→Phe、→Tyr）、Asp87位点（N = 22；→Asn、→Gly、→Tyr）以及parC基因（Thr57Ser，N = 23；Ala141Ser，N = 1）存在多个氨基酸替换。在gyrB和parE基因中未发现相关突变。12种由一到两个替换组合而成的模式与血清型和环丙沙星最低抑菌浓度均无关。在92株疑似质粒介导喹诺酮耐药的分离菌中发现了两个qnr等位基因：qnrS1（或qnrS3；N = 50）和qnrB19（或qnrB10；N = 24）。此外，两株具有染色体编码机制的分离菌携带qnrS1和qnrS2。所有测试分离菌的qnrA、qnrC、qnrD、qepA、aac(6')-Ib-cr均为阴性。在多个沙门氏菌血清型中均发现了染色体和质粒介导的喹诺酮耐药决定因素，并采用脉冲场凝胶电泳来评估所选分离菌（N = 82）的系统发育相似性。发现纽波特沙门氏菌积累了喹诺酮耐药决定因素，且该血清型通过可变的gyrA突变、qnrS1/S3或qnrB10/B19进行克隆传播。或者，各种决定因素分散在相关的肠炎沙门氏菌分离株中。抗菌选择压力、多种耐药决定因素以及它们的获得和传播情况使得对抗喹诺酮耐药性极为困难。
