Hutto D L, Galvin J E, Wannemuehler M J
Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, USA.
J Med Microbiol. 1998 Mar;47(3):275-80. doi: 10.1099/00222615-47-3-275.
This laboratory has previously reported a murine model of Serpulina hyodysenteriae infection in which mice fed a defined diet, Teklad 85420 (TD), developed caecal lesions more consistently than mice fed a conventional rodent chow (CRC). The objectives of the current studies were to characterise and compare the time of onset of lesions, the morphological nature and severity of lesions and the extent of colonisation by S. hyodysenteriae in mice fed the two diets. In the first of two experiments, 50 C3H/HeJ and 50 C3H/HeOuJ mice were fed either TD or CRC and then half of each group was infected with S. hyodysenteriae. Mice (n = 5) from each group were killed and examined on days, 1, 2, 4, 9 or 17 after infection. Each mouse was examined grossly and microscopically and assigned lesion scores based on lesion severity. The second experiment was designed in an identical way to the first, but had slightly smaller group sizes (n=20). Mice (n=4) were killed for necropsy at the same five time points after infection and their caeca were homogenised and examined by quantitative bacteriology with media selective for S. hyodysenteriae. There were no differences in any finding due to mouse strain. Group lesion scores over the entire experimental period were significantly higher in mice fed TD (mean total lesion index = 13) than in mice fed CRC (mean total lesion index = 8.8). Lesions were also temporally distributed in a significantly different manner in that they appeared earlier (day 1) and persisted longer in the TD-fed mice in comparison to CRC-fed mice. Furthermore, lesions of equivalent severity from each treatment group presented identical microscopic features. Finally, quantitative bacteriological results indicated that there was no significant difference in the number of cfu of S. hyodysenteriae isolated from mice fed TD and those fed CRC. These results demonstrate that the characteristic severe lesions associated with S. hyodysenteriae infection in mice can occur 1 day after oral challenge in mice fed Teklad diet 85420. Bacteriological results further indicate that the enhancement of lesion formation in this model is not due to any significant effect of the diet on numbers of spirochaetes in the caeca of infected mice.
本实验室先前报道过一种猪痢疾蛇形螺旋体感染的小鼠模型，在该模型中，喂食特定日粮Teklad 85420（TD）的小鼠比喂食传统啮齿动物饲料（CRC）的小鼠更易出现盲肠病变。当前研究的目的是对喂食这两种日粮的小鼠病变的发病时间、病变的形态学特征和严重程度以及猪痢疾蛇形螺旋体的定植范围进行表征和比较。在两项实验中的第一项实验中，给50只C3H/HeJ和50只C3H/HeOuJ小鼠喂食TD或CRC，然后每组中的一半小鼠感染猪痢疾蛇形螺旋体。在感染后的第1、2、4、9或17天，处死并检查每组中的5只小鼠。对每只小鼠进行大体和显微镜检查，并根据病变严重程度给出病变评分。第二项实验的设计与第一项相同，但每组小鼠数量略少（n = 20）。在感染后的相同五个时间点处死4只小鼠进行尸检，并将其盲肠匀浆，用对猪痢疾蛇形螺旋体有选择性的培养基进行定量细菌学检查。未发现因小鼠品系不同而产生的差异。在整个实验期间，喂食TD的小鼠的组病变评分（平均总病变指数 = 13）显著高于喂食CRC的小鼠（平均总病变指数 = 8.8）。病变在时间上的分布也有显著差异，与喂食CRC的小鼠相比，喂食TD的小鼠病变出现得更早（第1天）且持续时间更长。此外，来自每个治疗组的同等严重程度的病变呈现出相同的微观特征。最后，定量细菌学结果表明，从喂食TD的小鼠和喂食CRC的小鼠中分离出的猪痢疾蛇形螺旋体的cfu数量没有显著差异。这些结果表明，在喂食Teklad日粮85420的小鼠中，口服攻击后1天即可出现与猪痢疾蛇形螺旋体感染相关的典型严重病变。细菌学结果进一步表明，该模型中病变形成的增强并非由于日粮对感染小鼠盲肠中螺旋体数量有任何显著影响。
