BACKGROUND To confirm the hypothesis that Salmonella enterica subspecies enterica serovar (S.) Infantis has higher basic reproductive rates in chicks compared with other Salmonella serovars, 1-day-old specific-pathogen-free chicks (n = 8) were challenged simultaneously with S. Infantis and S. Typhimurium per os. Challenged chicks (Group A) were then housed with non-infected chicks (Group B, n = 4) for 6 days (from 2 to 8 days of age). Group B birds were then housed with other non-infected birds (Group C, n = 4), which were then transferred to cages containing a further group of untreated chicks (Group D, n = 2). A control group consisting of four non-infected chicks was used for comparison. All chickens were humanely sacrificed at 18 days of age, and Salmonella from bowel and liver samples were enumerated. RESULTS Both serovars were isolated from all groups except the control group. S. Typhimurium was isolated at a greater frequency than S. Infantis from the bowel samples of chicks from Groups B, C and D, while no differences in colonisation rates were observed between the two serovars in liver samples from Groups B, C and D. S. Typhimurium, but not S. Infantis, was immunohistochemically detected in the lamina propria of the cecum and rectum in five birds of Group A. Despite the competitive administration, neither of the two serovars completely excluded the other, and no differences were observed in basic reproductive rates between the two serovars. CONCLUSIONS These findings, together with data from previous studies, suggest that the initial quantitative domination of S. Infantis in chicken flocks may explain why this serovar is predominant in broiler chickens.

中文翻译：

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同时口服雏鸡沙门氏菌和鼠伤寒沙门氏菌。

背景技术为证实这一假设，即肠沙门氏菌亚种小肠沙门氏菌（S.）比其他沙门氏菌血清具有更高的基本繁殖率，同时对1天龄无特定病原体的小鸡（n = 8）进行了攻击。婴儿和鼠伤寒沙门氏菌 然后将受攻击的雏鸡（A组）与未感染的雏鸡（B组，n = 4）一起饲养6天（2至8天大）。然后将B组鸡与其他未感染的鸡（C组，n = 4）一起圈养，然后将其转移到包含另一组未经处理的雏鸡（D组，n = 2）的笼子中。将由四只未感染小鸡组成的对照组用于比较。在18日龄时将所有鸡人道处死，并从肠和肝脏样本中沙门氏菌计数。结果从对照组中分离出所有血清型。从B，C和D组的雏鸡的肠道样本中分离到鼠伤寒沙门氏菌的频率要比S. Infantis高，而在B，C和DS组的鼠肝样本中两种血清型之间的定殖率没有差异。在A组五只鸟类的盲肠和直肠固有层中未检测到S. Infantis，尽管进行了竞争性管理，但两种血清型均未完全排斥另一种，基本繁殖率未见差异在两个血清型之间。结论这些发现以及以前的研究数据表明，S的初步定量优势。