Systemic mycobacteriosis caused by ‘Mycobacterium aviumsubspecies hominissuis’ in a 14-month-old Japanese black beefsteer

[摘要] A 14-month-old Japanese black beef steer presented with severe chronic diarrhea andemaciation and was euthanized. Postmortem examination showed thickened and corrugatedintestinal mucosa and enlarged granulomatous mesenteric lymph nodes with caseatingnecrosis. Numerous epithelioid cells and multinucleated giant cells infiltrated in thelamina propria and the submucosal tissue of the intestines. These cells were also observedin the systemic organs. Many acid-fast bacilli were detected in the cytoplasm of thesecells and were identified as ‘Mycobacterium avium subsp.hominissuis’ (Mah) on the basis of the results ofmolecular examinations and immunohistochemistry. These findings indicate thatMah can cause systemic mycobacteriosis, and this unique infection needsto be distinguished from Johne’s disease and tuberculosis in cattle.

[学科分类] 兽医学

[关键词] caseating granuloma;cattle;chronic diarrhea;Mycobacterium avium subsp. hominissuis