Del Collo Laura P, Karns Jeffrey S, Biswas Debabrata, Lombard Jason E, Haley Bradd J, Kristensen R Camilla, Kopral Christine A, Fossler Charles P, Van Kessel Jo Ann S
Environmental Microbial and Food Safety Laboratory, USDA-Agricultural Research Service, Beltsville, MD 20705; Department of Animal and Avian Sciences, University of Maryland, College Park 20742.
Environmental Microbial and Food Safety Laboratory, USDA-Agricultural Research Service, Beltsville, MD 20705.
J Dairy Sci. 2017 May;100(5):3470-3479. doi: 10.3168/jds.2016-12084. Epub 2017 Feb 23.
Campylobacter spp. are frequently isolated from dairy cows as commensal organisms. Sporadic Campylobacter infections in humans in the United States are generally attributed to poultry, but outbreaks are also commonly associated with dairy products, particularly unpasteurized or raw milk. Bulk tank milk samples and milk filters from US dairy operations were collected during the National Animal Health Monitoring System Dairy 2014 study and analyzed using real-time PCR and traditional culture techniques for the presence of thermophilic Campylobacter species. The weighted prevalence of operations from which we detected Campylobacter spp. in either bulk tank milk or milk filters was 24.9%. We detected Campylobacter spp. in a higher percentage of operations with 100-499 cows (42.8%) and 500 or more cows (47.5%) than in operations with 30-99 cows (6.5%). Campylobacter spp. were also more frequently detected in operations in the west than the east (45.9 and 22.6%, respectively). We isolated Campylobacter spp. from approximately half of PCR-positive samples, representing 12.5% (weighted prevalence) of operations. The majority (91.8%) of isolates were C. jejuni, but C. lari and C. coli were also isolated. We detected resistance to tetracycline in 68.4% of C. jejuni isolates, and resistance to ciprofloxacin and nalidixic acid in 13.2% of C. jejuni isolates. Based on pulsed-field gel electrophoresis, we found that dairy-associated C. jejuni were genotypically diverse, although clonal strains were isolated from different geographic regions. These results suggest that bulk tank milk can be contaminated with pathogenic Campylobacter spp., and that the consumption of unpasteurized or raw milk presents a potential human health risk.
弯曲杆菌属通常作为共生生物从奶牛中分离出来。在美国，人类偶尔发生的弯曲杆菌感染一般归因于家禽，但疫情暴发也通常与乳制品有关，尤其是未经过巴氏杀菌的牛奶或生牛奶。在2014年国家动物卫生监测系统奶牛研究期间，采集了美国奶牛场的大罐牛奶样本和牛奶过滤器，并使用实时PCR和传统培养技术分析了嗜热弯曲杆菌属的存在情况。我们在大罐牛奶或牛奶过滤器中检测到弯曲杆菌属的养殖场加权患病率为24.9%。与拥有30 - 99头奶牛的养殖场（6.5%）相比，我们在拥有100 - 499头奶牛（42.8%）和500头及以上奶牛（47.5%）的养殖场中检测到弯曲杆菌属的比例更高。在西部养殖场中检测到弯曲杆菌属的频率也高于东部（分别为45.9%和22.6%）。我们从大约一半的PCR阳性样本中分离出弯曲杆菌属，占养殖场的12.5%（加权患病率）。分离出的菌株大多数（91.8%）为空肠弯曲菌，但也分离出了海鸥弯曲菌和大肠弯曲菌。我们在68.4%的空肠弯曲菌分离株中检测到对四环素的耐药性，在13.2%的空肠弯曲菌分离株中检测到对环丙沙星和萘啶酸的耐药性。基于脉冲场凝胶电泳，我们发现与乳制品相关的空肠弯曲菌在基因上具有多样性，尽管从不同地理区域分离出了克隆菌株。这些结果表明，大罐牛奶可能被致病性弯曲杆菌属污染，食用未经过巴氏杀菌的牛奶或生牛奶会对人类健康构成潜在风险。
