Takaoka Health and Welfare Center, Toyama, Japan.
Department of Animal Hygiene, School of Veterinary Medicine, Kitasato University, Aomori, Japan.
J Vet Med Sci. 2024 Jun 1;86(6):600-605. doi: 10.1292/jvms.24-0067. Epub 2024 Apr 16.
To investigate the etiological role of vapB-positive Rhodococcus equi in pigs, R. equi was isolated from the submaxillary lymph nodes with or without macroscopically detectable lesions of apparently healthy growing-finishing pigs at a slaughterhouse in Toyama Prefecture, Japan. R. equi was isolated from 57 (24.6%) of 232 pigs with macroscopically detectable lymph node lesions, and 56 (98.2%) of the 57 isolates were vapB-positive. R. equi was isolated from 10 (2.4%) of 420 pigs without lymph node lesions, and six (60%) of the 10 isolates were vapB-positive. Plasmid DNA was isolated from the 62 vapB-positive isolates and digested with EcoRI and NsiI to obtain the plasmid profile. Fifty-two (83.9%), three (4.8%), and four (6.5%) isolates contained pVAPB subtypes 1, 2, and 3, respectively, while the remaining three isolates were of pVAPB subtypes 9, 13, and 14, respectively. Twelve specimens from lymph nodes with macroscopically detectable lesions were randomly selected for histopathological staining. Granulomatous lesions resembling tuberculosis were found in 11 of the 12 specimens, and the remaining specimen showed typical foci of malakoplakia in the lymph node. The isolation rates of R. equi and vapB-positive R. equi from lymph nodes with macroscopically detectable lesions were significantly higher (P<0.05) than those of lymph nodes without lesions, suggesting an etiologic association between vapB-positive R. equi and macroscopically detectable granulomatous lesions in porcine submaxillary lymph nodes. Previous reports on the prevalence of vapB-positive R. equi in pigs are reviewed and discussed.
为了研究 vapB 阳性马红球菌在猪中的病因作用，我们从日本富山县一家屠宰场的下颌淋巴结中分离出了有或没有肉眼可见病变的看似健康的生长-育肥猪的 R. equi。从 232 头有肉眼可见淋巴结病变的猪中分离出 57 株（24.6%）R. equi，其中 56 株（98.2%）为 vapB 阳性。从 420 头无淋巴结病变的猪中分离出 10 株（2.4%）R. equi，其中 6 株（60%）为 vapB 阳性。从 62 株 vapB 阳性分离株中提取质粒 DNA，并用 EcoRI 和 NsiI 消化获得质粒图谱。52 株（83.9%）、3 株（4.8%）和 4 株（6.5%）分离株分别含有 pVAPB 亚型 1、2 和 3，而其余 3 株分别为 pVAPB 亚型 9、13 和 14。从有肉眼可见病变的淋巴结中随机选择 12 个标本进行组织病理学染色。在 12 个标本中的 11 个中发现了类似于结核病的肉芽肿病变，而其余的标本在淋巴结中显示了典型的马尔科拉卡akia 病灶。有肉眼可见病变的淋巴结中 vapB 阳性 R. equi 和 R. equi 的分离率明显高于无病变淋巴结（P<0.05），表明 vapB 阳性 R. equi 与猪下颌淋巴结中肉眼可见的肉芽肿病变之间存在病因关联。本文回顾和讨论了以前关于 vapB 阳性 R. equi 在猪中的流行率的报道。
