Gast Richard K, Guraya Rupa, Guard Jean, Holt Peter S
United States Department of Agriculture, Agricultural Research Service, Egg Safety and Quality Research Unit, Russell Research Center, 950 College Station Road, Athens, GA 30605, USA.
Avian Dis. 2011 Jun;55(2):243-7. doi: 10.1637/9540-092810-Reg.1.
Contamination of eggs by Salmonella Enteritidis has been a prominent cause of human illness for several decades and is the focus of a recently implemented national regulatory plan for egg-producing flocks in the United States. Salmonella Heidelberg has also been identified as an egg-transmitted pathogen. The deposition of Salmonella strains inside eggs is a consequence of reproductive tract colonization in infected laying hens, but prior research has not determined the relationship between the numbers of Salmonella that colonize reproductive organs and the associated frequency of egg contamination. In the present study, groups of laying hens in two trials were experimentally infected with large oral doses of strains of Salmonella Enteritidis (phage type 13a), Salmonella Heidelberg, or Salmonella Hadar. Reproductive tissues of selected hens were cultured to detect and enumerate Salmonella at 5 days postinoculation, and the interior contents of eggs laid between 6 and 25 days postinoculation were tested for contamination. Significantly more internally contaminated eggs were laid by hens infected with Salmonella Enteritidis (3.58%) than with strains of either Salmonella Heidelberg (0.47%) or Salmonella Hadar (0%). However, no significant differences were observed between Salmonella strains in either isolation frequency or the number of colony-forming units (CFU) isolated from ovaries or oviducts. Salmonella isolation frequencies ranged from 20.8% to 41.7% for ovaries and from 8.3% to 33.3% for oviducts. Mean Salmonella colonization levels ranged from 0.10 to 0.51 log CFU/g for ovaries and from 0.25 to 0.46 log CFU/g for oviducts. Although parallel rank-orders were observed for Salmonella enumeration (in both ovaries and oviducts) and egg contamination frequency, a statistically significant relationship could not be established between these two parameters of infection.
几十年来，肠炎沙门氏菌污染鸡蛋一直是人类疾病的一个突出原因，也是美国最近实施的一项针对产蛋鸡群的国家监管计划的重点。海德堡沙门氏菌也被确定为一种通过鸡蛋传播的病原体。鸡蛋内部沙门氏菌菌株的沉积是受感染产蛋母鸡生殖道定植的结果，但先前的研究尚未确定生殖器官定植的沙门氏菌数量与相关鸡蛋污染频率之间的关系。在本研究中，两组产蛋母鸡在两项试验中经口大量接种肠炎沙门氏菌（噬菌体分型13a）、海德堡沙门氏菌或哈达尔沙门氏菌菌株。在接种后5天对选定母鸡的生殖组织进行培养以检测和计数沙门氏菌，并对接种后6至25天所产鸡蛋的内部内容物进行污染检测。感染肠炎沙门氏菌的母鸡所产内部受污染鸡蛋（3.58%）明显多于感染海德堡沙门氏菌菌株（0.47%）或哈达尔沙门氏菌（0%）的母鸡。然而，在分离频率或从卵巢或输卵管分离的菌落形成单位（CFU）数量方面，沙门氏菌菌株之间未观察到显著差异。卵巢的沙门氏菌分离频率在20.8%至41.7%之间，输卵管的分离频率在8.3%至33.3%之间。卵巢的平均沙门氏菌定植水平在0.10至0.51 log CFU/g之间，输卵管的平均沙门氏菌定植水平在0.25至0.46 log CFU/g之间。尽管在沙门氏菌计数（卵巢和输卵管中）和鸡蛋污染频率方面观察到平行的排序，但这两个感染参数之间未能建立统计学上的显著关系。
