Jones Deana R, Gast Richard K, Regmi Prafulla, Ward Garrett E, Anderson Kenneth E, Karcher Darrin M
U.S. Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Egg Safety and Quality Research Unit, Athens, Georgia 30605.
Department of Animal Sciences, Purdue University, West Lafayette, Indiana 47907.
J Food Prot. 2020 Jun 1;83(6):943-950. doi: 10.4315/JFP-19-467.
Environmental testing for Salmonella Enteritidis is required for U.S. shell egg producers with ≥3,000 hens on a farm. The egg producer assumes all costs for the mandatory testing. According to the U.S. Food and Drug Administration (FDA) Egg Rule, either manure scraper or drag swabs can be collected according to published guidelines and requirements. The present study was undertaken to determine the efficacy of Salmonella detection with one-, two-, and four-swab pools of either manure scraper or drag swabs. Resistant isolates of Salmonella serovars Enteritidis (1,000 ppm of streptomycin), Heidelberg (200 ppm of nalidixic acid [NA]), Typhimurium (200 ppm of NA), and Kentucky (200 ppm of NA) were utilized. Low (approximately 8.4 CFU) and high (approximately 84 CFU) levels of inocula were introduced onto a single swab within a pool. Single flocks from each conventional cage (manure scraper swabs) and cage-free barn (drag swabs) were monitored throughout the study at the ages required under the FDA Egg Rule. The highest and most consistent recovery of inoculum was found in single swab samples. For low dose inocula, recovery of isolates was low from single manure scraper swabs (57.9 to 29.2%) and decreased as more swabs were added to the pool. Recovery of isolates from manure scraper swabs was higher for high dose inocula, although Salmonella Heidelberg was outcompeted by the naturally occurring flora and had the lowest rate of recovery among the isolates tested. One- and two-swab pools of drag swabs had similar rates of recovery at both low and high doses for Salmonella Enteritidis, Salmonella Heidelberg, and Salmonella Typhimurium. When Salmonella Enteritidis and Salmonella Kentucky were combined in an inoculum, Salmonella Enteritidis was recovered at a much higher rate than was Salmonella Kentucky for all types of swabs and doses of inocula. Pooling of two drag swabs allowed for similar detection of low and high dose Salmonella, but the pooling of manure scraper swabs decreased detection of low dose Salmonella.
对于美国农场中饲养母鸡数量≥3000只的蛋鸡生产商，需要对肠炎沙门氏菌进行环境检测。蛋鸡生产商承担强制检测的所有费用。根据美国食品药品监督管理局（FDA）的《蛋类规定》，可按照已发布的指南和要求采集粪便刮板样本或拖拭样本。本研究旨在确定粪便刮板样本或拖拭样本单拭子、双拭子和四拭子组合用于检测沙门氏菌的效果。使用了肠炎沙门氏菌（1000 ppm链霉素）、海德堡沙门氏菌（200 ppm萘啶酸[NA]）、鼠伤寒沙门氏菌（200 ppm NA）和肯塔基沙门氏菌（200 ppm NA）的耐药菌株。将低水平（约8.4 CFU）和高水平（约84 CFU）的接种物接种到一个组合拭子中的单个拭子上。在整个研究过程中，按照FDA《蛋类规定》要求的年龄，对每个传统鸡笼（粪便刮板拭子）和无笼鸡舍（拖拭样本）中的单个鸡群进行监测。在单拭子样本中发现接种物的回收率最高且最稳定。对于低剂量接种物，单粪便刮板拭子中分离株的回收率较低（57.9%至29.2%），且随着组合中拭子数量的增加而降低。对于高剂量接种物，粪便刮板拭子中分离株的回收率较高，不过海德堡沙门氏菌在自然菌群中竞争力较弱，在所测试的分离株中回收率最低。对于肠炎沙门氏菌、海德堡沙门氏菌和鼠伤寒沙门氏菌，拖拭样本的单拭子和双拭子组合在低剂量和高剂量时的回收率相似。当接种物中同时含有肠炎沙门氏菌和肯塔基沙门氏菌时，对于所有类型的拭子和接种物剂量，肠炎沙门氏菌的回收率都远高于肯塔基沙门氏菌。双拖拭样本组合能够相似地检测低剂量和高剂量的沙门氏菌，但粪便刮板拭子组合会降低低剂量沙门氏菌的检测率。
