Duchet-Suchaux M, Léchopier P, Marly J, Bernardet P, Delaunay R, Pardon P
Institut National de la Recherche Agronomique, Pathologie Infectieuse et Immunologie, Centre de Tours-Nouzilly, Monnaie, France.
Avian Dis. 1995 Oct-Dec;39(4):796-803.
Quantification of the carrier state of Salmonella enteritidis in chicks (i.e., persistent asymptomatic association of S. enteritidis with the host), should provide an optimized means for further investigations into this problem. We therefore developed an experimental carrier state model by oral inoculation of low doses (10(2)-10(4)) of S. enteritidis in B13 chicks at different ages. Liver, spleen, and ceca colonizations by the challenge strains were measured weekly by enumeration of S. enteritidis colony-forming units (CFU) for 7-12 weeks. High mortality rates, incompatible with the carrier state, were observed in chicks inoculated with 10(2) organisms of either a parental strain of S. enteritidis (5556) or a mutant resistant to streptomycin (Smr) and nalidixic acid (Nalr) (strain 1009) at 1 day old. Both strains colonized organs similarly, allowing us to use subsequently the SmrNalr mutant strain. The selected low doses of S. enteritidis induced no deaths in chicks inoculated at 1 or 3 weeks of age. However, inoculation of 3-week-old chicks did not induce a satisfactory carrier state; organ colonization by S. enteritidis was weak and transient, even after inoculation of 10(8) SE. In contrast, some birds infected at 1 week of age presented the challenge strain in the liver and spleen for 3 weeks after inoculation and in the ceca for 12 weeks postchallenge. Most of these birds were colonized by S. enteritidis in the liver and in the ceca for 3 weeks and 10 weeks, respectively, following inoculation. Generally, CFU levels were highest during the first week(s) after inoculation and then decreased progressively. Levels of S. enteritidis were lower in the liver and spleen than in the ceca. Oral inoculation of 1-week-old birds with 5 x 10(4) S. enteritidis provided the required model, allowing quantification of the carrier state of S. enteritidis in chicks.
对雏鸡中肠炎沙门氏菌携带状态（即肠炎沙门氏菌与宿主的持续性无症状关联）进行定量分析，应为进一步研究该问题提供一种优化方法。因此，我们通过给不同年龄的B13雏鸡口服低剂量（10² - 10⁴）的肠炎沙门氏菌，建立了一个实验性携带状态模型。通过每周对肠炎沙门氏菌菌落形成单位（CFU）进行计数，持续7 - 12周，来检测攻击菌株在肝脏、脾脏和盲肠的定植情况。在1日龄时接种10²个肠炎沙门氏菌亲本菌株（5556）或对链霉素（Smr）和萘啶酸（Nalr）耐药的突变株（菌株1009）的雏鸡中，观察到高死亡率，这与携带状态不符。两种菌株在器官中的定植情况相似，因此我们随后使用了SmrNalr突变株。选定的低剂量肠炎沙门氏菌在1周龄或3周龄接种的雏鸡中未导致死亡。然而，接种3周龄雏鸡并未诱导出令人满意的携带状态；即使接种10⁸个肠炎沙门氏菌，肠炎沙门氏菌在器官中的定植也很微弱且短暂。相比之下，一些1周龄感染的雏鸡在接种后3周内在肝脏和脾脏中呈现出攻击菌株，在攻毒后12周内在盲肠中呈现。这些雏鸡中的大多数在接种后，肠炎沙门氏菌分别在肝脏和盲肠中定植3周和10周。一般来说，CFU水平在接种后的第一周内最高，然后逐渐下降。肠炎沙门氏菌在肝脏和脾脏中的水平低于盲肠。给1周龄雏鸡口服5×10⁴个肠炎沙门氏菌提供了所需的模型，可用于定量分析雏鸡中肠炎沙门氏菌的携带状态。
