What is Colitis and How to Treat and Manage It
Colitis encompasses multiple inflammatory conditions of the colon, each requiring distinct treatment approaches based on the specific type, location, and severity of disease.
Types of Colitis
1. Ulcerative Colitis (UC)
The most common chronic inflammatory bowel disease affecting the colon, with treatment stratified by disease extent and severity 1, 2.
2. Microscopic Colitis
Includes lymphocytic and collagenous colitis, presenting with watery diarrhea despite minimal endoscopic changes 3.
3. Immune Checkpoint Inhibitor (ICI) Colitis
An immune-related adverse event from cancer immunotherapy, with endoscopic findings ranging from normal to IBD-like changes 4, 3.
4. Infectious Colitis
Caused by various pathogens requiring antimicrobial therapy 5.
Treatment Approach for Ulcerative Colitis
Ulcerative Proctitis (Rectum Only)
Start with topical 5-ASA suppositories as first-line therapy 1.
- If no response or intolerance: Add oral 5-ASA or switch to topical corticosteroids
- Refractory cases: Consider oral corticosteroids, topical tacrolimus, JAK inhibitors, S1P agonists, or biologic therapy 1
Mild to Moderate Left-Sided or Extensive Colitis
Initiate oral 5-ASA, preferably combined with topical 5-ASA enemas (which reach the splenic flexure) 1, 6.
- Assess response at 2-4 weeks
- If inadequate response: Start oral corticosteroids (prednisolone)
- Once remission achieved: Continue 5-ASA maintenance therapy
- Critical caveat: Corticosteroids are NEVER used for long-term maintenance 1
Moderate to Severe Ulcerative Colitis
Begin prednisolone combined with 5-ASA immediately 1.
Alternative approach: High-dose 5-ASA alone can be attempted, but if no response within 2 weeks, immediately escalate to corticosteroids 1.
Escalation criteria for advanced therapy (biologics/small molecules):
- No adequate response to oral corticosteroids within 2 weeks
- Unsuccessful corticosteroid taper
- Need to avoid repeated corticosteroid courses 1
Advanced Therapy Selection
The choice between biologics (infliximab, vedolizumab, ustekinumab) and small molecules (JAK inhibitors, S1P agonists) requires consideration of:
- Patient and disease factors
- Prior treatment history
- Local availability and reimbursement 1
For maintenance: Continue the agent that successfully induced remission. Purine analogues can be used but typically require induction with another agent (often corticosteroids), and are suggested alongside infliximab therapy 1.
Treatment Approach for ICI Colitis
ICI colitis responds rapidly to treatment (typically <1 week), contrasting with IBD 4.
Mild Cases
- Budesonide (colonically formulated) is highly effective for microscopic colitis pattern from ICIs 4
- Many patients can continue immunotherapy while on budesonide 4
Moderate to Severe or Steroid-Refractory Cases
Escalate to biologic therapy with either infliximab or vedolizumab 4, 3.
Infliximab selection considerations:
- Avoid in hematologic malignancies (risk of rare lymphomas)
- Use with caution in severe congestive heart failure
- Consider carefully if concurrent ICI hepatitis present (infliximab can induce hepatitis) 4
Vedolizumab selection considerations:
- May interfere with antitumor responses in primary GI malignancies or GI metastases 4
If first biologic fails: Switch treatment class (infliximab to vedolizumab or vice versa) within weeks—do NOT wait for standard washout period given severity 4.
Refractory to both biologics: Consider ustekinumab, tofacitinib, or abatacept in life-threatening cases, though each carries substantial risk of interfering with antitumor responses 4.
Treatment Approach for Microscopic Colitis
First-line: Budesonide 3.
Budesonide-refractory cases: Biologics have shown successful outcomes in recent studies 3.
Important reassurance: Microscopic colitis does NOT confer added risk for colorectal cancer 3.
Treatment Approach for Infectious Colitis
Diagnosis requires multiplex PCR followed by guided culture on PCR-positive pathogens 5.
- PCR confirms active infection rapidly
- Standard culture provides isolates for antibiotic susceptibility testing, subtyping, and Whole Genome Sequencing 5
Treatment: Antimicrobials guided by culture and susceptibility results 5.
Critical differential: Must distinguish from neutropenic colitis, drug-induced colitis, and inflammatory bowel disease to prevent complications like toxic megacolon 5.
Key Treatment Goals and Monitoring
The treatment paradigm has shifted from clinical response to achieving complete remission 1.
Remission should be assessed:
- Biochemically
- Endoscopically
- Histologically 1
This approach aims to prevent long-term disease complications 1.
Common Pitfalls to Avoid
- Never use corticosteroids for maintenance therapy in UC 1
- Do not delay biologic therapy in steroid-refractory UC—escalate within 2 weeks 1
- In ICI colitis switching biologics, do not wait for washout periods—treat within weeks if failing first agent 4
- Prophylactic budesonide does NOT prevent ICI enterocolitis (shown in RCT), but treats microscopic colitis pattern effectively 4
- Distinguish ICI colitis from IBD—ICI colitis responds much faster (typically <1 week vs weeks for IBD) 4