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

Abstract

Case summaryThis 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 informationThe 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.

Escherichia coli‐associated granulomatous colitis in a cat

“…In cats, despite no genetic basis for GC to date, this and other case reports demonstrate intracellular E. coli within granulomatous colonic lesions. [9][10][11] This would seem, at least in part, to support E. coli as the causative agent for GC in cats. Studies investigating cats for a potential underlying genetic basis, such as candidate gene NCF2 mutations in humans and dogs, are needed.…”

“…To date, this represents only the fourth reported adult cat with confirmed PAS+ GC. [9][10][11] In this particular case, the presence of severe macrophage infiltration on colonic histopathology prompted concern for an infectious aetiology. Faecal PCR testing and special stains on the biopsies excluded parasitic, fungal, and other noninvasive bacteria as causes for the granulomatous colonic infiltrate.…”

“…8 The decision to treat with a fluoroquinolone was extrapolated from the current recommendations in successfully treated dogs and two prior feline case reports. 5,9,10 One of the limitations in this case was the lack of a bacterial culture for guiding antibiotic selection. In dogs, obtaining this information prior to starting treatment is important because of fluoroquinolone resistance, particularly when administered prior to a definitive diagnosis.…”

“…Like prior cases, this report also confirms both a bacterial aetiology and successful response to antimicrobial treatment for GC in the cat. [9][10][11]…”

“…To date, only three feline cases of GC have been reported, a five‐year‐old Persian, a four‐year‐old domestic shorthair, and a 10‐year‐old domestic shorthair 9–11 . All cases had colonic histopathology lesions identical to that of canine GC and long‐standing remission following the administration of either a fluoroquinolone 9,10 antibiotic or chloramphenicol 11 .…”