苏北地区白羽肉鸡父母代种鸡及其商品鸡中沙门氏菌的分离、鉴定与生物特性

Isolation, identification and characterization of Salmonella from a parental breeder farm of white broiler and its commercial chickens in northern Jiangsu

摘要:

【背景】沙门氏菌是一种重要的人兽共患食源性致病菌，控制沙门氏菌在动物中的感染和在食品生产链中的污染对于畜牧生产、公共卫生和食品安全具有重要意义。【目的】调查苏北地区某白羽肉鸡父母代种鸡及其商品鸡的沙门氏菌感染和流行情况，为其沙门氏菌防治提供参考依据。【方法】于2018?2019年从江苏泰州、宿迁、盐城、徐州、连云港等地区分别采集某白羽肉鸡父母代种鸡场产蛋鸡及其商品鸡场1?2日龄弱雏和10日龄雏鸡的泄殖腔拭子样品共360份，进行沙门氏菌的分离与鉴定，用纸片法和PCR方法对菌株耐药表型及相关耐药基因进行检测，通过多位点序列分型(multilocus sequence typing，MLST)技术对分离菌株的亲缘关系进行研究。【结果】从120份父母代产蛋鸡分离到3株沙门氏菌，从120份商品代1?2日龄弱雏分离到25株沙门氏菌，从120份商品代10日龄雏鸡分离到82株沙门氏菌。分离的沙门氏菌对多粘菌素B、亚胺培南、多西环素、甲氧苄啶、替加环素、氟苯尼考、头孢噻肟、恩诺沙星表现为全部敏感，对呋喃妥因、青霉素、利福平、利奈唑胺、万古霉素均表现为全部耐药；对阿莫西林耐药的菌株有30株(占27.27%)，敏感的有80株(占72.73%)。耐药基因的PCR检测结果显示：β内酰胺类耐药基因blaTEM存在于所有沙门氏菌分离株中，但其他常见耐药基因在本研究的分离株中未发现。通过对分离菌7对管家基因进行PCR扩增、测序和MLST分型，发现所有沙门氏菌分离株的ST型均为ST11，属于肠炎沙门氏菌。MLST分型结果结合药敏试验结果表明，分离的沙门氏菌属于同一进化系统，具有相同或相似的来源。【结论】被调查商品鸡群的肠炎沙门氏菌感染很可能是其同一来源的父母代种鸡场垂直传播所致，这为该地区白羽肉鸡的沙门氏菌防治提供了参考。

Abstract:

[Background] Salmonella is an important zoonotic foodborne pathogen. Therefore, controlling of Salmonella infection in animals and pollution in the food production chain has great significance for livestock production, public health and food safety. [Objective] Studying the infection and epidemic of Salmonella from a parental breeder farm of white broiler and its commercial chickens in northern Jiangsu will provide a reference for the prevention and control of Salmonella. [Methods] A total of 360 samples of cloaca swabs were collected from farms in Taizhou, Suqian, Yancheng and Lianyungang from 2018 to 2019, including 120 samples from parental breeders, their 1 or 2 days old weak commercial broilers and 10 days old commercial broilers, respectively. Then, the Salmonellas were isolated and identified, their drug resistance phenotypes and genotypes were characterized by Kirby-Bauer and PCR methods, and the genetic relationship of the isolates was analyzed by multilocus sequence typing (MLST). [Results] In total, 120 Salmonella strains were isolated, including 3 strains from the parental breeders, 25 strains from the 1 or 2 days old weak commercial broilers and 82 strains from the 10 days old commercial broilers. By using Kirby-Bauer test, all strains were found to be sensitive to antibiotics polymyxin B, imipenem, doxycycline, trimethoprim, tigecycline, florfenicol, cefotaxime and enrofloxacin, and resistant to macrodantin, penicillin, rifampicin, linezolid and vancomycin. Moreover, 80 isolates (72.73%) were sensitive to antibiotic amoxicillin while the other 30 strains (27.27%) were resistant to it. The drug-resistant genes analyzed by PCR showed that blaTEM existed in all isolates, but not other common resistance genes. The ST type of all Salmonella isolates in this study was identified as ST11 based on the MLST typing and sequencing results of 7 pairs of housekeeping genes. Collectively, out data demonstrate that the phylogenies of these Salmonella isolates are very similar. [Conclusion] Salmonella infections occurred in the commercial broilers seemed to be caused by vertical transmission from the same herds of parental breeders. This study provided a reference for the prevention and control of Salmonella in white broiler farms in this area.