Granulomatous colitis: more than a canine disease? A case of Escherichia coli-associated granulomatous colitis in an adult cat

Abstract

Case summary: This report describes a 4-year-old cat with chronic intermittent haematochezia and faecal incontinence of 7 months' duration. Investigation revealed severe colonic multifocal mucosal ulcerations and infiltration of the mucosal lamina propria by large numbers of periodic acid-Schiff-positive macrophages. Fluorescence in situ hybridisation analysis of colonic biopsies revealed multifocal clusters of intracellular Escherichia coli. Treatment with fluoroquinolones for 6 weeks led to a complete resolution of clinical signs.

Relevance and novel information: The findings reveal that mucosally invasive E coli can also be associated with granulomatous colitis in cats and indicate the need for diagnostic testing of mucosal samples for E coli and other infectious agents.

Figure 1

Colonoscopy showed thick irregular mucosa with multiple superficial ulcers (first image 11 o’clock). The mucosa was friable and bled easily during the procedure

Figure 2

Histopathology of colonic biopsies showed accumulation of macrophages with abundant cytoplasm containing periodic acid–Schiff (PAS)-positive material throughout mucosal lamina propria (original photos: LAPVSO). H&E = haematoxylin and eosin

Figure 3

Fluorescence in situ hybridisation of colonic biopsies showing multifocal clusters of invasive intracellular rods (EUB-338, upper row) that hybridised with a probe to Escherichia coli/Shigella species (lower row), similar to granulomatous colitis in dogs. Bacteria stain red (cy-3). Nuclei/DNA stain blue (4’,6-diamidino-2-phenylindole)