Jejunal granuloma associated with an argyrophilic gram-negative non-segmented filamentous bacterium in a Holstein cow

A length of intussuscepted jejunum, associated with a granuloma, was removed surgically from a 35-month-old Holstein cow. Microscopically, the granuloma consisted of multifocal aggregates of macrophages, epithelioid cells and occasional multinucleated giant cells within the lamina propria. Numerous argyrophilic, gram-negative, periodic acid Schiff-negative, non-segmented, long filamentous bacteria (2-17 microm in length, 0.1-0.3 microm in diameter) were detected in the cytoplasm of the epithelioid cells. The bacteria were localized to the granulomatous lesions. Comparative 16S rDNA gene sequencing analysis revealed that the organism was an unpublished species (accession number AB472332). This argyrophilic non-segmented filamentous bacterium appears to have been the cause of multifocal granulomatous jejunitis accompanied by intestinal intussusception in this cow.