Campylobacter species and neutrophilic inflammatory bowel disease in cats

Background - Inflammatory bowel disease (IBD) is a common cause of signs of gastrointestinal disease in cats. A subset of cats with IBD has neutrophilic inflammation of the intestinal mucosa.

Hypothesis - Neutrophilic enteritis in cats is associated with mucosal invasion by microorganisms, and specifically Campylobacter spp.

Animals - 7 cats with neutrophilic IBD and 8 cats with lymphoplasmacytic IBD.

Methods – Retrospective review of duodenal biopsy samples that were collected endoscopically for histologic examination. Cases were identified and selected by searching the histopathology archive for cats with a diagnosis of neutrophilic and lymphoplasmacytic IBD. Fluorescence in situ hybridisation (FISH) targeting either all eubacteria or individual Campylobacter spp. was performed on archived samples. Neutrophils were detected on the same samples using a FISH probe for neutrophil elastase.

Results - C. coli was present in (6/7) cats with neutrophilic IBD and in (1/8) cats with lymphoplasmacytic IBD (P=0.009). Cats with neutrophilic IBD had significantly higher numbers of C. coli (median bacteria 0.7/hpf) in the mucosa than cats with lymphoplasmacytic IBD (median bacteria 0/hpf) (P=0.004). Co-localisation of neutrophils and C. coli was demonstrated, with C. coli closer to the neutrophils than any other bacteria (P<0.001).

Conclusions and clinical importance - identification of C. coli associated with neutrophilic inflammation suggests that C. coli is able either to produce compounds which stimulate neutrophils or to induce feline intestinal cells to produce neutrophil chemoattractants. This association should allow a directed therapeutic approach in cats with neutrophilic IBD, potentially improving outcome and reducing any zoonotic risk.