Thibodeau V, Frost E H, Chénier S, Quessy S
Department of Microbiology, Faculty of Medicine, University of Sherbrooke, Quebec.
Can J Vet Res. 1999 Apr;63(2):96-100.
In order to study the early events associated with infection of swine by Yersinia enterocolitica, 42 five-week-old crossbred piglets were inoculated per os with approximately 10(8) Y. enterocolitica O:3. Groups of 5 animals (and one negative control) were euthanized 30 min, 3, 6, 12, 24, 48 and 72 h following the infection. Palatine tonsils, retropharyngeal and mesenteric lymph nodes, esophagus, duodenum, jejunum, ileum (and Peyer's patches), stomach, liver, spleen and feces (from colon) were collected and analyzed for the presence of Y. enterocolitica by standard bacteriological procedures. Natural infections were also analyzed, as a complementary study, by taking one-gram samples of fecal material and tonsils from 291 pig carcasses less than 3 h after slaughter and culturing them for Y. enterocolitica using a cold enrichment technique. Within 30 min, Yersinia enterocolitica O:3 was already present at most sites. The presence of Y. enterocolitica in the liver of 3 out of 10 animals and also in the spleen of 3 out of 10 piglets, within the first 3 h postinfection, but not at later times (with one exception), probably indicated a transient bacteremia accompanying the initial stages of infection. The tonsils were colonized in most animals (13/20) as the bacteria remained present from 12 to 72 h postinfection, while only 4 out of 20 fecal samples were found to be positive over the same period. Up to 10(4) colony-forming units of Y. enterocolitica per gram of tonsil and fecal material were recovered. Finally, among the 291 animals sampled at the abattoir, a total of 79 were found positive, 70 of the tonsils sampled were positive, and bacteria were recovered in 17 fecal samples. It is therefore suggested that palatine tonsils are the most reliable tissue for the indication of an infection/colonization by Y. enterocolitica O:3 in swine and that the removal of this tissue during the slaughter process should be considered in order to minimize the possibility of contamination of meat products.
为了研究与小肠结肠炎耶尔森菌感染猪相关的早期事件，给42头5周龄的杂交仔猪经口接种约10⁸小肠结肠炎耶尔森菌O:3。在感染后30分钟、3小时、6小时、12小时、24小时、48小时和72小时，对每组5只动物（和1个阴性对照）实施安乐死。采集腭扁桃体、咽后和肠系膜淋巴结、食管、十二指肠、空肠、回肠（和派伊尔结）、胃、肝脏、脾脏以及粪便（来自结肠），并通过标准细菌学程序分析小肠结肠炎耶尔森菌的存在情况。作为一项补充研究，还对自然感染进行了分析，方法是在屠宰后不到3小时从291头猪的尸体上采集1克粪便样本和扁桃体样本，采用冷增菌技术对其进行小肠结肠炎耶尔森菌培养。在30分钟内，小肠结肠炎耶尔森菌O:3已出现在大多数部位。在感染后最初3小时内，10只动物中有3只的肝脏以及10头仔猪中有3只的脾脏中存在小肠结肠炎耶尔森菌，但在之后的时间里（有一个例外）均未发现，这可能表明在感染初期伴有短暂菌血症。大多数动物（13/20）的扁桃体被定植，因为细菌在感染后12至72小时一直存在，而在同一时期，20份粪便样本中只有4份呈阳性。每克扁桃体和粪便样本中回收的小肠结肠炎耶尔森菌菌落形成单位高达10⁴。最后，在屠宰场采样的291只动物中，共有79只呈阳性，70份采样的扁桃体呈阳性，17份粪便样本中培养出了细菌。因此，建议腭扁桃体是指示猪感染/定植小肠结肠炎耶尔森菌O:3最可靠的组织，并且在屠宰过程中应考虑切除该组织，以尽量减少肉类产品受污染的可能性。
