Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands; Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands.
Centre for Infectious Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands.
Vet Microbiol. 2021 Jul;258:109120. doi: 10.1016/j.vetmic.2021.109120. Epub 2021 May 15.
Salmonella Infantis is a poultry-adapted Salmonella enterica serovar that is increasingly reported in broilers and is also regularly identified among human salmonellosis cases. An emerging S. Infantis mega-plasmid (pESI), carrying fitness, virulence and antimicrobial resistance genes, is also increasingly found. We investigated the prevalence, genetic characteristics and risk factors for (pESI-carrying) S. Infantis in broilers. Faecal samples from 379 broiler flocks (in 198 farms with ≥3000 birds) in the Netherlands were tested. A questionnaire about farm characteristics was also administered. Sampling was performed in July 2018-May 2019, three weeks before slaughter. Fourteen flocks (in 10 farms) were S. Infantis-positive, resulting in a 3.7 % flock-level and 5.1 % farm-level prevalence. Based on multi-locus sequence typing (MLST), all isolates belonged to sequence type 32. All but one isolate carried a pESI-like mega-plasmid. Core-genome MLST showed considerable heterogeneity among the isolates, even within the same farm, with a few small clusters detected. The typical pESI-borne multi-resistance pattern to aminoglycosides, sulphonamide and tetracycline (93 %), as well as trimethoprim (71 %), was found. Additionally, resistance to (fluoro)quinolones based on gyrA gene mutations was detected. S. Infantis was found more often in flocks using salinomycin as coccidiostat, where flock thinning was applied or litter quality was poor, whereas employing external cleaning companies, wheat in feed, and vaccination against infectious bronchitis, were protective. Suggestive evidence for vertical transmission from hatcheries was found. A heterogeneous (pESI-carrying) S. Infantis population has established itself in Dutch broiler flocks, calling for further monitoring of its spread and a comprehensive appraisal of control options.
婴儿沙门氏菌是一种适应家禽的沙门氏菌肠杆菌血清型，在肉鸡中越来越多地被报告，并且在人类沙门氏菌病病例中也经常被发现。一种新兴的婴儿沙门氏菌大型质粒（pESI），携带适应性、毒力和抗微生物药物耐药性基因，也越来越多地被发现。我们调查了肉鸡中（pESI 携带）婴儿沙门氏菌的流行率、遗传特征和危险因素。从荷兰的 198 个农场（每个农场有≥3000 只鸡）的 379 个肉鸡鸡群中采集粪便样本。还进行了关于农场特征的问卷调查。采样于 2018 年 7 月至 2019 年 5 月进行，在屠宰前 3 周进行。有 14 个鸡群（10 个农场）呈婴儿沙门氏菌阳性，鸡群和农场的流行率分别为 3.7%和 5.1%。基于多位点序列分型（MLST），所有分离株均属于序列型 32。除一个分离株外，所有分离株均携带 pESI 样大型质粒。核心基因组 MLST 显示，即使在同一农场内，分离株之间也存在相当大的异质性，检测到一些小的聚类。发现了典型的 pESI 携带的对氨基糖苷类、磺胺类和四环素（93%）以及甲氧苄啶（71%）的多耐药模式。此外，还检测到基于 gyrA 基因突变的对（氟）喹诺酮类药物的耐药性。在使用盐霉素作为球虫抑制剂、应用鸡群分层或垫料质量差、使用外部清洁公司、在饲料中添加小麦以及接种传染性支气管炎疫苗的鸡群中，婴儿沙门氏菌更为常见。发现了来自孵化场的垂直传播的提示性证据。一种异质的（pESI 携带）婴儿沙门氏菌群体已经在荷兰肉鸡鸡群中建立起来，这需要进一步监测其传播情况，并全面评估控制选择。
