Department of Population Health & Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA; Comparative Medicine Institute, North Carolina State University, Raleigh, NC 27607, USA.
Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC 27607, USA.
Int J Food Microbiol. 2020 Apr 16;319:108472. doi: 10.1016/j.ijfoodmicro.2019.108472. Epub 2019 Dec 30.
The interaction of typical host adapted enteric bacterial pathogens with fresh produce grown in fields is complex. These interactions can be more pronounced in co-managed or sustainable farms where animal operations are, by design, close to fresh produce, and growers frequently move between the two production environments. The primary objectives of this study were to 1) determine the transmission of STEC or enteric pathogens from small and large animal herds or operations to fresh produce on sustainable farms in TN and NC, 2) identify the possible sources that impact transmission of AMR E. coli, specifically STEC on these systems, and 3) WGS to characterize recovered E. coli from these sources. Samples were collected from raw and composted manure, environment, and produce sources. The serotype, virulence, and genotypic resistance profile were determined using the assembled genome sequences sequenced by Illumina technology. Broth microdilution was used to determine the antimicrobial susceptibility of each isolate against a panel of fourteen antimicrobials. The prevalence of E. coli increased during the summer season for all sources tested. ParSNP trees generated demonstrated that the transmission of AMR E. coli is occurring between animal feeding operations and fresh produce. Ten isolates were identified as serotype O45, a serotype that is associated with the "Big Six" group that is frequently linked with foodborne outbreaks caused by non-O157 E. coli. However, these isolates did not possess the stx gene. The highest frequency of resistance was detected against streptomycin (n = 225), ampicillin (n = 190) and sulfisoxazole FIS (n = 140). A total of 35 (13.7%) isolates from two TN farms were positive for the blaCMY (n = 5) and blaTEM (n = 32) genes. The results of this study show the potential of AMR E. coli transmission between animal feeding operations and fresh produce, and more studies are recommended to study this interaction and prevent dissemination in sustainable farming systems.
典型宿主适应的肠道细菌病原体与田间种植的新鲜农产品之间的相互作用是复杂的。这些相互作用在共同管理或可持续农场中更为明显，在这些农场中，动物作业的设计是靠近新鲜农产品的，种植者经常在这两种生产环境之间移动。本研究的主要目的是：1）确定 STEC 或肠道病原体是否从田纳西州和北卡罗来纳州可持续农场的小和大动物群或作业传播到新鲜农产品，2）确定影响 AMR 大肠杆菌传播的可能来源，特别是 STEC 在这些系统中的传播，以及 3）WGS 来表征从这些来源回收的大肠杆菌。样品取自生肥和堆肥、环境和农产品来源。使用 Illumina 技术测序的组装基因组序列确定血清型、毒力和基因型耐药谱。肉汤微量稀释法用于确定每个分离株对十四种抗菌药物的药敏性。在所有测试的来源中，大肠杆菌的患病率在夏季增加。生成的 ParSNP 树表明，AMR 大肠杆菌的传播正在动物饲养作业和新鲜农产品之间发生。鉴定出的 10 个分离株为 O45 血清型，该血清型与“六大”组有关，该组经常与由非 O157 大肠杆菌引起的食源性暴发有关。然而，这些分离株不携带 stx 基因。对链霉素（n=225）、氨苄西林（n=190）和磺胺甲恶唑 FIS（n=140）的耐药率最高。来自田纳西州的两个农场的 35 株（13.7%）分离株对 blaCMY（n=5）和 blaTEM（n=32）基因呈阳性。本研究的结果表明，动物饲养作业与新鲜农产品之间存在 AMR 大肠杆菌传播的潜力，建议进行更多研究以研究这种相互作用并防止在可持续农业系统中传播。
