Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.
Department of Food Hygiene and Aquaculture, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.
Microb Pathog. 2019 Jul;132:355-361. doi: 10.1016/j.micpath.2019.05.018. Epub 2019 May 13.
It is important to evaluate the antimicrobial resistance pattern by genotypic and phenotypic methods in epidemiological studies in order to control antimicrobial resistance and to improve the outcome of the treatments. Four-hundred and thirty clinical mastitis samples were collected from 14 dairy herds in five different cities. The antimicrobial susceptibility test was performed using agar disk diffusion for 70 identified Escherichia coli isolates. The antimicrobial resistance genes including strA, strB, aadA, sulI, sulII, sulIII, ampC were detected by PCR method. Phylogenic groups were determined by Clermont's multiplex PCR method, and RAPD typing was performed on all isolates. Most isolates were resistant to lincomicin and streptomycin, whereas sulfa-trimethoprim has the lowest resistance rate. Moreover, ampC, aadA and sul2 genes had the highest frequency (92.85%, 38.57%, and 32.85% respectively). 20% of all the isolates carried strA and strB genes, and 11.42% of the isolates had sul1 gene and 10% of the isolates had the less frequent sul3 gene. Of the total of 70 E. coli isolates, 26 (37.14%), 20 (28.5%), 17 (24.2%), 8 (11.4%) isolates belonged to B1, A, B2 and D phylogenic groups respectively. strA, strB, sul2and aadA resistance genes had the highest percentage in A phylogenic groups. Based on RAPD-PCR method, E. coli isolates were classified in four clusters. The result showed a high phenotypic and genotypic E. coli resistance to the current antimicrobials with a similar pattern in different cities; also the majority of E. coli isolates belonged to B1 group which mainly contains the commensal E. coli isolates.
在流行病学研究中，通过基因和表型方法评估抗菌药物耐药模式，对于控制抗菌药物耐药性和改善治疗效果非常重要。从五个不同城市的 14 个奶牛场采集了 430 份临床乳腺炎样本。对 70 株鉴定为大肠杆菌的分离株进行琼脂平板扩散药敏试验。采用 PCR 法检测 strA、strB、aadA、sulI、sulII、sulIII 和 ampC 等抗菌药物耐药基因。采用 Clermont 多重 PCR 法确定菌群群，对所有分离株进行 RAPD 分型。大多数分离株对林可霉素和链霉素耐药，而磺胺-三甲氧嘧啶的耐药率最低。此外，ampC、aadA 和 sul2 基因的频率最高（分别为 92.85%、38.57%和 32.85%）。所有分离株中 20%携带 strA 和 strB 基因，11.42%携带 sul1 基因，10%携带较少见的 sul3 基因。在 70 株大肠杆菌分离株中，26（37.14%）、20（28.5%）、17（24.2%）和 8（11.4%）株分别属于 B1、A、B2 和 D 菌群群。A 菌群群中 strA、strB、sul2 和 aadA 耐药基因的比例最高。基于 RAPD-PCR 方法，将大肠杆菌分离株分为 4 个聚类。结果表明，目前的抗菌药物对大肠杆菌表现出较高的表型和基因型耐药性，不同城市的耐药模式相似；大多数大肠杆菌分离株属于 B1 群，主要包含共生的大肠杆菌分离株。
