Clinical characteristics and long-term outcome of E. coli-associated granulomatous ileocolitis in dogs: five cases (2010-2014)

Fluorescent In Situ Hybridization for the Detection of Intracellular Bacteria in Companion Animals

FISH techniques have been applied for the visualization and identification of intracellular bacteria in companion animal species. Most frequently, these techniques have focused on the identification of adhesive-invasive Escherichia coli in gastrointestinal disease, although various other organisms have been identified in inflammatory or neoplastic gastrointestinal disease. Previous studies have investigated a potential role of Helicobacter spp. in inflammatory gastrointestinal and hepatic conditions. Other studies evaluating the role of infectious organisms in hepatopathies have received some attention with mixed results. FISH techniques using both eubacterial and species-specific probes have been applied in inflammatory cardiovascular, urinary, and cutaneous diseases to screen for intracellular bacteria. This review summarizes the results of these studies.

Repeat histopathology and culture of colonic biopsy specimens after treatment for Escherichia coli-associated granulomatous colitis in a cat

Case summary

A 7.5-year-old neutered male Oriental Shorthair cat presented with an 8-month history of haematochezia, mucoid diarrhoea, tenesmus and vocalisation after a 4-year history of small bowel diarrhoea. Transabdominal ultrasonography confirmed diffuse colonic wall thickening and extensive ulceration and erythema after colonoscopy. Colonic histopathology confirmed periodic acid-Schiff positive macrophages, consistent with granulomatous colitis; Escherichia coli was cultured from colonic biopsy specimens. Fluorescent in situ hybridisation (FISH) identified intracellular E coli, and an 8-week oral course of marbofloxacin, a hydrolysed protein diet and a 5-day course of fenbendazole yielded a transient partial clinical remission of the colitis signs. A reported resolution in the small bowel signs was also reported. Colonoscopy was repeated 5 months later due to the recurrence of colitis signs. Histopathology was not consistent with granulomatous colitis supporting a complete remission; however, a chronic inflammatory enteropathy was confirmed with moderate lymphoplasmacytic, neutrophilic and eosinophilic colitis without a histiocytic component. E coli was again cultured from colonic biopsies with sensitivity to fluoroquinolones; FISH was positive for intracellular E coli. Clinical signs persisted despite a 2-week course of oral marbofloxacin.

Relevance and novel information

E coli-associated granulomatous colitis is rare in cats. Colonic biopsy specimen culture is important to guide appropriate antibiotic therapy. Repeat histopathology, culture and FISH have not been previously reported after treatment of a cat with E coli-associated granulomatous colitis. Persistent clinical signs after treatment with oral marbofloxacin alongside a confirmed complete histologic remission support the presence of a concurrent chronic inflammatory enteropathy and pathology for the cat's ongoing colitis.

Role of adherent invasive Escherichia coli in pathogenesis of inflammatory bowel disease

Gut microbiota imbalances play an important role in inflammatory bowel disease (IBD), but no single pathogenic microorganism critical to IBD that is specific to the IBD terminal ileum mucosa or can invade intestinal epithelial cells has been found. Invasive Escherichia coli (E. coli) adhesion to macrophages is considered to be closely related to the pathogenesis of inflammatory bowel disease. Further study of the specific biological characteristics of adherent invasive E. coli (AIEC) may contribute to a further understanding of IBD pathogenesis. This review explores the relationship between AIEC and the intestinal immune system, discusses the prevalence and relevance of AIEC in Crohn's disease and ulcerative colitis patients, and describes the relationship between AIEC and the disease site, activity, and postoperative recurrence. Finally, we highlight potential therapeutic strategies to attenuate AIEC colonization in the intestinal mucosa, including the use of phage therapy, antibiotics, and anti-adhesion molecules. These strategies may open up new avenues for the prevention and treatment of IBD in the future.

Influence and Implications of the Molecular Paradigm of Nitric Oxide Underlying Inflammatory Reactions of the Gastrointestinal Tract of Dog: A Major Hallmark of Inflammatory Bowel Disease

Nitric oxide (NO), a pleiotropic free radical messenger molecule, is responsible for the various cellular function of the gastrointestinal mucosa. It plays a major role in the maintenance of perfusion, regulation of microvascular, epithelial permeability, and immune functions. Nitric oxide exerts its beneficial effect on the initiation and maintenance of inflammation in human inflammatory bowel disease (IBD). But the accelerated production of NO triggers activation of the inducible form of the NO synthase enzyme (iNOS) that leads to damages of the intestinal membrane. Nitric oxide synthase enzyme is responsible for the higher production of NO from l-arginine and causes an inflammatory condition in the intestinal epithelium. Nitric oxide induces nitrative DNA damage and oxidative DNA damage in the cellular system. Accelerated production of NO enhances iNOS activity that is associated with cytotoxicity and apoptosis of gastrointestinal epithelial cells in the dog. Chronic inflammation leads to angiogenesis that is modulated by the immune system in IBD. Chronic inflammation is a major risk factor for the development of gastrointestinal malignancies. Nitric oxide participates in mucosal inflammation in the intestine through invigoration of NO synthase enzyme. The intrinsic complex mechanism is correlated with the inflammation in the gastrointestinal tract and is also correlated with the expression of iNOS, enzymatic activity and NO production. Nitric oxide employs a significant role in modulating epithelial permeability with accelerated immune response in acute colitis. But the enormous generation of NO causes adverse effects on the mucosal cell during the inflammatory process in IBD. In this review, a complex episode of NO generation with altered biochemical pathways was assessed for the regulation of mucosal inflammation in inflammatory bowel disease of dogs. This review is a unique compilation of the role of NO in the pathogenesis of inflammatory bowel disease of dogs. Nitric oxide plays a key role in modulating cancer in the gastrointestinal tract. This review seeks to explore the characteristics of NO as a major hallmark of canine inflammatory bowel diseases.