What are the treatment options for infectious vs inflammatory colitis?

Treatment Options for Infectious vs Inflammatory Colitis

The treatment of colitis should be guided by the underlying etiology, with infectious causes requiring antimicrobial therapy while inflammatory bowel disease requires anti-inflammatory medications, immunomodulators, or biologics depending on disease severity.

Distinguishing Between Infectious and Inflammatory Colitis

Diagnostic Approach

• Infectious causes of diarrhea should be excluded before diagnosing and treating inflammatory bowel disease (IBD) 1
• Stool testing for inflammatory markers (lactoferrin and calprotectin) can help stratify high-risk patients for endoscopic evaluation 1, 2
• Endoscopic confirmation of diagnosis and severity should be considered before initiating high-dose systemic glucocorticoids for suspected IBD 1
• Multiplex PCR followed by guided culture can confirm active infection while standard culture methods provide isolates for antibiotic susceptibility testing 3

Clinical Differentiation

• Infectious colitis typically presents with acute onset (81% of cases), early fever, and presentation within 1 week of symptom onset 4
• IBD often has insidious onset (56% of cases) or warning signs such as previous bowel symptoms and absence of early fever 4
• Basal plasmocytosis on histology is the strongest predictor of IBD, rarely found in infectious colitis 4

Treatment of Infectious Colitis

Clostridium difficile Infection (CDI)

• For initial episode of non-severe CDI: metronidazole 500 mg three times daily orally for 10 days 1
• For severe CDI: vancomycin 125 mg four times daily orally for 10 days 1
• If oral therapy is impossible: metronidazole 500 mg three times daily intravenously for 10 days 1
• For severe CDI with oral therapy impossible: add intracolonic vancomycin 500 mg in 100 mL normal saline every 4-12 hours 1
• For second recurrence and later recurrences: vancomycin 125 mg four times daily orally for at least 10 days, consider taper/pulse strategy 1

Other Infectious Colitis

• For febrile dysenteric diarrhea: empiric treatment with 1000 mg azithromycin in a single dose for adults 2
• For Shigella, Salmonella, and Campylobacter: pathogen-specific antimicrobial therapy should be initiated once laboratory diagnosis is made 2
• Avoid antibiotics for Shiga toxin-producing E. coli (STEC) infections as treatment may increase risk of complications 1, 2
• Be aware that ciprofloxacin, while effective for infectious colitis, may cause drug-induced pancreatitis in approximately 3% of patients 5

Treatment of Inflammatory Bowel Disease

Ulcerative Colitis (UC)

Mild to Moderate Distal UC

• First-line therapy: topical mesalazine 1 g daily combined with oral mesalazine 2-4 g daily 1
• Second-line therapy (for those intolerant to topical mesalazine): topical corticosteroids 1
• For patients failing combination therapy: oral prednisolone 40 mg daily, with topical agents as adjunctive therapy 1
• Prednisolone should be reduced gradually over 8 weeks according to severity and patient response 1

Severe UC

• Requires admission for intensive intravenous therapy 1
• Joint management by gastroenterologist and colorectal surgeon 1
• Daily physical examination, vital signs monitoring, stool charting, and laboratory tests 1
• Intravenous fluid and electrolyte replacement, blood transfusion to maintain hemoglobin >10 g/dL 1
• Subcutaneous heparin to reduce thromboembolism risk 1
• Nutritional support if malnourished 1
• Acute onset UC can be difficult to distinguish from infectious colitis, but treatment with corticosteroids should not be delayed until stool microbiology results are available 1

Crohn's Disease (CD)

Active Ileal or Ileocolonic CD

• Treatment options include high-dose mesalazine, corticosteroids, nutritional therapy, or surgery based on disease severity 1
• Infliximab 5 mg/kg is effective but should be avoided in patients with obstructive symptoms 1, 6
• Surgery should be considered for those who have failed medical therapy 1

Fistulating and Perianal Disease

• Metronidazole 400 mg three times daily and/or ciprofloxacin 500 mg twice daily for simple perianal fistulae 1
• Azathioprine 1.5-2.5 mg/kg/day or mercaptopurine 0.75-1.5 mg/kg/day for simple perianal or enterocutaneous fistulae 1
• Infliximab (three infusions of 5 mg/kg at 0,2, and 6 weeks) for refractory fistulae 1, 6
• Surgical options including Seton drainage, fistulectomy, and advancement flaps in combination with medical treatment 1

Maintenance Therapy

Ulcerative Colitis

• Lifelong maintenance therapy generally recommended, especially for left-sided or extensive disease 1
• Options include aminosalicylates, azathioprine, or mercaptopurine 1
• Discontinuation may be reasonable for distal disease in remission for 2 years 1

Crohn's Disease

• Smoking cessation is the most important factor in maintaining remission 1
• Azathioprine 1.5-2.5 mg/kg/day or mercaptopurine 0.75-1.5 mg/kg/day are effective but reserved as second-line therapy due to potential toxicity 1
• Methotrexate (15-25 mg IM weekly) is effective for patients whose active disease has responded to IM methotrexate 1

Special Considerations

Immune Checkpoint Inhibitor Colitis

• Exclude infectious causes before treatment 1
• Typically responds to high-dose systemic glucocorticoids (0.5-2 mg/kg prednisone equivalent daily with a 4-6 week taper) 1
• Infliximab and vedolizumab are reasonable options for glucocorticoid-refractory colitis 1

Refractory Proctitis and Distal Colitis

• Review symptoms, treatment history, and adherence to medical therapy 1
• Reassess diagnosis by stool culture, endoscopy, and biopsy 1
• Check for proximal constipation which may affect drug delivery 1
• Options for truly refractory disease include IV steroid therapy, oral or rectal cyclosporine, oral or rectal tacrolimus, or infliximab 1

Pitfalls and Caveats

• Antiperistaltic agents and opiates should be avoided in CDI 1
• Avoid antibiotics for STEC infections as they may increase risk of complications 1
• Acute onset UC can mimic infectious colitis, but corticosteroid treatment should not be delayed until stool microbiology results are available 1
• Consider C. difficile infection in any patient with bloody diarrhea, particularly those with healthcare exposure or recent antibiotics 1
• Ciprofloxacin can cause drug-induced pancreatitis in approximately 3% of patients treated for infectious colitis 5