Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
Foodborne Pathog Dis. 2010 Jul;7(7):815-23. doi: 10.1089/fpd.2009.0481.
The objective of this study was to determine if the within-herd prevalence of fecal Salmonella shedding is higher in dairy herds with clinical outbreaks of disease, as compared to herds with subclinical infections only. Data were collected prospectively from dairy herds throughout New York that had at least 150 lactating cows and that received clinical service from participating veterinarians. After enrollment, Salmonella surveillance consisted of both environmental screening and disease monitoring within the herd. Herds positive by either environmental or fecal culture were sampled during three visits to estimate the within-herd prevalence of Salmonella. We characterized isolates by serovar and antimicrobial resistance pattern. Among 57 enrolled herds, 44 (77%) yielded Salmonella-positive samples during the study period; 27 (61%) of the positive herds had Salmonella isolated from environmental samples only, and 17 (39%) had one or more laboratory-confirmed clinical cases. The within-herd prevalence of fecal Salmonella shedding ranged from 0 to 53%. Salmonella Cerro was the predominant serovar, accounting for 56% of all isolates. Antimicrobial resistance ranged from zero to nine drugs, and 14 (32%) of the positive farms generated multidrug-resistant isolates. Herds with laboratory-confirmed clinical cases had a higher prevalence of fecal Salmonella shedding than herds that only generated positive environmental samples, as estimated by a Poisson regression model (prevalence ratio, 2.7; p = 0.01). An association between dairy herd outbreaks of salmonellosis and a higher prevalence of asymptomatic shedding should help guide strategies for reducing the public health threat of Salmonella, as the ability to recognize high-risk herds by clinical laboratory submissions presents an obvious opportunity to maximize food safety at the preharvest level. This is in contrast with other foodborne zoonotic pathogens, such as Campylobacter jejuni and Escherichia coli O157:H7, which occur widely in adult cattle without accompanying clinical disease.
本研究旨在确定在有临床疾病暴发的奶牛场中，与仅有亚临床感染的奶牛场相比，粪便沙门氏菌脱落的场内流行率是否更高。数据是从整个纽约的奶牛场中前瞻性收集的，这些奶牛场至少有 150 头泌乳奶牛，并接受参与兽医的临床服务。登记后，沙门氏菌监测包括场内环境筛查和疾病监测。通过环境或粪便培养阳性的牛群在三次访问中采样，以估计场内沙门氏菌的流行率。我们根据血清型和抗生素耐药模式对分离株进行了特征描述。在 57 个入组的牛群中，44 个（77%）在研究期间产生了沙门氏菌阳性样本；27 个（61%）阳性牛群仅从环境样本中分离出沙门氏菌，17 个（39%）有一个或多个实验室确诊的临床病例。粪便沙门氏菌脱落的场内流行率为 0 至 53%。沙门氏菌 Cerro 是主要的血清型，占所有分离株的 56%。抗生素耐药范围从 0 到 9 种药物，14 个（32%）阳性农场产生了多药耐药分离株。通过泊松回归模型估计，与仅产生阳性环境样本的牛群相比，实验室确诊的临床病例牛群的粪便沙门氏菌脱落流行率更高（流行率比，2.7；p = 0.01）。奶牛场沙门氏菌病暴发与无症状脱落率较高之间的关联，应有助于指导减少沙门氏菌对公共卫生威胁的策略，因为通过临床实验室提交识别高风险牛群的能力为最大限度地提高收获前食品安全提供了明显的机会。这与其他食源性人畜共患病病原体（如空肠弯曲菌和大肠杆菌 O157：H7）形成对比，这些病原体广泛存在于成年牛中，而无伴随的临床疾病。
