Kinde Hailu, Goodluck Helen A, Pitesky Maurice, Friend Tom D, Campbell James A, Hill Ashley E
A California Animal Health and Food Safety Laboratory System (CAHFS), San Bernardino Branch, School of Veterinary Medicine, 105 W. Central Avenue, San Bernardino, CA 92408.
B Cooperative Extension, School of Veterinary Medicine, Davis, CA 95616.
Avian Dis. 2015 Dec;59(4):548-53. doi: 10.1637/11224-063015-ResNote.1.
Single swabs (cultured individually) are currently used in the Food and Drug Administration (FDA) official method for sampling the environment of commercial laying hens for the detection of Salmonella enterica ssp. serovar Enteritidis (Salmonella Enteritidis). The FDA has also granted provisional acceptance of the National Poultry Improvement Plan's (NPIP) Salmonella isolation and identification methodology for samples taken from table-egg layer flock environments. The NPIP method, as with the FDA method, requires single-swab culturing for the environmental sampling of laying houses for Salmonella Enteritidis. The FDA culture protocol requires a multistep culture enrichment broth, and it is more labor intensive than the NPIP culture protocol, which requires a single enrichment broth. The main objective of this study was to compare the FDA single-swab culturing protocol with that of the NPIP culturing protocol but using a four-swab pool scheme. Single and multi-laboratory testing of replicate manure drag swab sets (n = 525 and 672, respectively) collected from a Salmonella Enteritidis-free commercial poultry flock was performed by artificially contaminating swabs with either Salmonella Enteritidis phage type 4, 8, or 13a at one of two inoculation levels: low, x¯ = 2.5 CFU (range 2.5-2.7), or medium, x¯ = 10.0 CFU (range 7.5-12). For each replicate, a single swab (inoculated), sets of two swabs (one inoculated and one uninoculated), and sets of four swabs (one inoculated and three uninoculated), testing was conducted using the FDA or NPIP culture method. For swabs inoculated with phage type 8, the NPIP method was more efficient (P < 0.05) for all swab sets at both inoculation levels than the reference method. The single swabs in the NPIP method were significantly (P < 0.05) better than four-pool swabs in detecting Salmonella Enteritidis at the lower inoculation level. In the collaborative study (n = 13 labs) using Salmonella Enteritidis phage type 13a inoculated swabs, there was no significant difference (P > 0.05) between the FDA method (single swabs) and the pooled NPIP method (four-pool swabs). The study concludes that the pooled NPIP method is not significantly different from the FDA method for the detection of Salmonella Enteritidis in drag swabs in commercial poultry laying houses. Consequently based on the FDA's Salmonella Enteritidis rule for equivalency of different methods, the pooled NPIP method should be considered equivalent. Furthermore, the pooled NPIP method was more efficient and cost effective.
目前，美国食品药品监督管理局（FDA）的官方方法采用单拭子（单独培养）对商业蛋鸡养殖环境进行采样，以检测肠炎沙门氏菌亚种肠炎血清型（肠炎沙门氏菌）。FDA还临时批准了国家家禽改良计划（NPIP）用于从食用蛋鸡群环境中采集样本的沙门氏菌分离和鉴定方法。与FDA方法一样，NPIP方法要求对蛋鸡舍进行环境采样时采用单拭子培养来检测肠炎沙门氏菌。FDA培养方案需要多步骤的培养富集肉汤，比NPIP培养方案更耗费人力，后者只需要一种富集肉汤。本研究的主要目的是将FDA单拭子培养方案与NPIP培养方案进行比较，但采用四拭子混合方案。通过用肠炎沙门氏菌4型、8型或13a型噬菌体以两种接种水平之一人工污染拭子，对从无肠炎沙门氏菌的商业家禽群中收集的重复粪便拖拭子组（分别为n = 525和672）进行单实验室和多实验室测试：低接种水平，x¯ = 2.5 CFU（范围2.5 - 2.7），或中等接种水平，x¯ = 10.0 CFU（范围7.5 - 12）。对于每个重复样本，使用FDA或NPIP培养方法对单个拭子（接种）、两个拭子组（一个接种和一个未接种）以及四个拭子组（一个接种和三个未接种）进行测试。对于接种8型噬菌体的拭子，在两个接种水平下，NPIP方法对所有拭子组都比参考方法更有效（P < 0.05）。在较低接种水平下，NPIP方法中的单个拭子在检测肠炎沙门氏菌方面明显（P < 0.05）优于四拭子混合组。在使用接种13a型肠炎沙门氏菌噬菌体拭子的协作研究（n = 13个实验室）中，FDA方法（单拭子）和NPIP混合方法（四拭子混合）之间没有显著差异（P > 0.05）。该研究得出结论，在商业家禽蛋鸡舍的拖拭子中检测肠炎沙门氏菌时，NPIP混合方法与FDA方法没有显著差异。因此，根据FDA关于不同方法等效性的肠炎沙门氏菌规定，NPIP混合方法应被视为等效。此外，NPIP混合方法更高效且具有成本效益。
