Colitis Causes and Characteristics

Infectious Causes

Bacterial pathogens, including Clostridium difficile, are common causes of infectious colitis, particularly in patients with recent antibiotic exposure 1, 2
Cytomegalovirus (CMV) infection can cause colitis, especially in immunocompromised patients or those with underlying IBD 1

The European Society of Gastrointestinal Endoscopy recommends that ulcerative colitis be characterized by continuous inflammation limited to the colon with rectal involvement 3, 4
Ulcerative colitis presents with bloody diarrhea, abdominal pain, urgency, and tenesmus, with disease extent varying from proctitis to pancolitis 4, 5
Crohn's disease is characterized by patchy, transmural inflammation that can affect any part of the gastrointestinal tract, and can be classified by location or pattern 3, 4
Indeterminate colitis/IBD-unclassified accounts for approximately 5% of IBD cases affecting the colon, with diagnosis relying on the presence of "overlapping features" or absence of a "clear diagnostic pattern" 3, 4, 6, 7

Collagenous colitis is characterized by increased subepithelial collagen and inflammation, presenting with chronic watery (non-bloody) diarrhea and normal or near-normal endoscopic appearance 1, 8
Lymphocytic colitis is characterized by increased intraepithelial lymphocytes, presenting with chronic watery diarrhea and normal endoscopic appearance 1, 8

Non-steroidal anti-inflammatory drugs (NSAIDs) can exacerbate existing colitis or cause new-onset colitis, while selective COX-2 inhibitors appear to be safer in short-term use 9
Antibiotics can disrupt normal gut flora, predisposing to C. difficile infection 2

Ischemic colitis is due to reduced blood flow to the colon, and is more common in older adults with vascular disease 4
Radiation colitis can occur following radiotherapy to the abdomen or pelvis 8
Bile acid malabsorption can cause diarrhea and inflammation, particularly in microscopic colitis 8
Food intolerances, such as maldigestion of fermentable carbohydrates (FODMAPs) and lactose, can cause symptoms similar to colitis 8

Genetic susceptibility plays a role in IBD development, with a stronger genetic component in Crohn's disease than in ulcerative colitis 4
Environmental triggers, such as smoking and prior appendectomy, interact with genetic susceptibility to influence IBD risk 4, 5, 9
Intestinal infections may trigger the onset of IBD or cause flares in established disease 1, 6
Alterations in gut microbiota contribute to various forms of colitis 4

Not all colitis presents with bloody diarrhea - microscopic colitis typically presents with watery, non-bloody diarrhea 1, 8
C. difficile infection in IBD patients may not present with typical pseudomembranes, making diagnosis challenging 1
When evaluating chronic diarrhea, consider microscopic colitis, which requires specific biopsies despite normal endoscopic appearance 8