Food Safety and Animal Health Division, Alberta Agriculture and Rural Development, Edmonton, Alberta, Canada.
Poult Sci. 2011 Mar;90(3):660-4. doi: 10.3382/ps.2010-00634.
Salmonella is one of the frequent causes of bacterial foodborne diseases with major public health impact in industrialized countries. Food-producing animals, in particular poultry, are major sources of human salmonellosis. Salmonella is normally found in the gastrointestinal tract of animals and can contaminate the carcass during the slaughtering process. In poultry, crops are also colonized by this pathogen. Crops are more likely to get ruptured during evisceration and contaminate the carcass and therefore present a health risk to consumers. Reducing Salmonella colonization in crops could decrease carcass contamination and is considered a potential preharvest critical control point in poultry production. Furthermore, rapid and reliable diagnostic methods to detect Salmonella are needed to monitor crop colonization to help ensure food safety. However, detection of Salmonella by bacteriological methods is time consuming and labor intensive and is not suitable for routine screening of a large number of samples. Therefore, this study was undertaken to validate a real-time PCR (RPCR) assay for the detection of Salmonella spp. in crop samples of broiler chickens. In total, 997 crop samples (35 spiked, 962 field) were processed by both RPCR and culture. The RPCR correctly identified all spiked crop samples. Out of 962 field crop samples, 100 tested positive by RPCR and 88 tested positive by culture for Salmonella, giving a sample level prevalence of 10.4 % (95% CI: 8.54 to 12.50%) and 9.1% (95% CI: 7.40 to 11.15%), respectively. The agreement beyond chance between RPCR and culture was 92% (P < 0.001) and 100% (P < 0.001) for field and spiked samples, respectively. Compared with culture, the sensitivity and specificity of RPCR were 98.86 and 98.51% for field samples and 100 and 100% for spiked samples, respectively. Where bacterial speciation is required, only the positive samples would be cultured. Therefore, RPCR can be used as a good screening tool for Salmonella spp. in crops by eliminating the time-consuming and labor-intensive culture of negative samples.
沙门氏菌是导致食源性细菌病的常见原因之一，对工业化国家的公共卫生有重大影响。食用动物，特别是家禽，是人类沙门氏菌病的主要来源。沙门氏菌通常存在于动物的胃肠道中，在屠宰过程中可能会污染胴体。在禽类中，这种病原体也会定植于嗉囊。在去脏过程中，嗉囊更容易破裂，污染胴体，因此对消费者构成健康风险。减少嗉囊中的沙门氏菌定植可降低胴体污染，并被认为是家禽生产中潜在的收获前关键控制点。此外，需要快速可靠的诊断方法来检测沙门氏菌，以监测嗉囊定植情况，帮助确保食品安全。然而，通过细菌学方法检测沙门氏菌既耗时又费力，不适合对大量样本进行常规筛选。因此，本研究旨在验证一种实时聚合酶链反应（RPCR）检测肉鸡嗉囊样本中沙门氏菌的方法。总共处理了 997 个嗉囊样本（35 个加标，962 个田间），分别用 RPCR 和培养法进行检测。RPCR 正确识别了所有加标嗉囊样本。在 962 个田间嗉囊样本中，有 100 个样本通过 RPCR 检测呈阳性，88 个样本通过培养法检测呈阳性，沙门氏菌的样本水平流行率分别为 10.4%（95%CI：8.54%至 12.50%）和 9.1%（95%CI：7.40%至 11.15%）。RPCR 与培养法的一致性分别为 92%（P < 0.001）和 100%（P < 0.001），对于田间和加标样本分别为 92%（P < 0.001）和 100%（P < 0.001）。与培养法相比，RPCR 对田间样本的灵敏度和特异性分别为 98.86%和 98.51%，对加标样本的灵敏度和特异性分别为 100%和 100%。如需进行细菌鉴定，只有阳性样本才需要进行培养。因此，RPCR 可用于通过消除对阴性样本的耗时费力的培养，作为一种检测嗉囊中沙门氏菌的良好筛选工具。
