What is the treatment approach for non-Clostridioides (C.) difficile associated colitis?

Treatment of Non-C. difficile Associated Colitis

For non-C. difficile colitis, treatment depends entirely on the underlying etiology—identify and treat the specific cause, whether infectious (bacterial, viral, parasitic), inflammatory (IBD), ischemic, or medication-induced.

Diagnostic Approach

The first critical step is determining the cause through appropriate testing:

• Stool cultures for entero-invasive bacterial pathogens (Salmonella, Shigella, Campylobacter, E. coli O157:H7) should be obtained in all patients presenting with acute colitis 1
• Microscopy and culture for amoebic or Shigella dysentery in patients with relevant travel history 1
• CMV testing via colonic biopsies (H&E staining, immunohistochemistry, or quantitative tissue PCR) in moderate to severe colitis, particularly in corticosteroid-refractory disease 1
• Rule out C. difficile infection with stool assay, as this fundamentally changes management 1

Treatment by Etiology

Infectious Colitis (Non-C. difficile)

Bacterial Pathogens:

• Salmonella, Shigella, Campylobacter: Most cases are self-limited and do not require antibiotics in immunocompetent patients. However, in patients on immunosuppressive therapy, these infections are more severe 1
• Withhold immunomodulators until active bacterial infections are resolved 1
• Anti-TNF therapy should be withdrawn during active infection, with infectious disease consultation before reintroduction 1

CMV Colitis:

• Diagnosed by typical CMV inclusions on H&E stain, immunohistochemistry, or tissue PCR 1
• Risk factors include refractory disease, immunomodulator use, age >30 years, and corticosteroid use 1
• Treatment requires antiviral therapy (typically ganciclovir or valganciclovir), though specific regimens are not detailed in the provided guidelines

Parasitic Infections:

• Amoebic dysentery requires specific antiparasitic treatment based on identification 1

Inflammatory Bowel Disease (IBD) Flares

When colitis is due to underlying IBD without superimposed infection:

• Maintain appropriate IBD treatment to prevent flares, as disease activity carries risks of adverse outcomes 1
• Acute flares require prompt treatment without delay to prevent complications 1
• Corticosteroids, immunomodulators, and biologics are used based on disease severity and prior response, following IBD-specific guidelines 1

Ischemic Colitis

While not explicitly covered in the provided guidelines, management typically involves:

• Supportive care with bowel rest and IV fluids
• Correction of underlying causes (hypotension, cardiac issues)
• Surgical consultation if perforation or peritonitis develops

Critical Management Principles

Immunosuppression Considerations

A careful risk-benefit evaluation is essential when managing colitis in immunosuppressed patients:

• Stop other antibiotics if possible when treating infectious colitis 1
• Pneumococcal vaccination should be offered before starting immunomodulators, ideally 2 weeks before treatment 1
• Screen for latent tuberculosis before anti-TNF therapy 1
• Patients on immunomodulators experience more severe infections with Salmonella, Listeria, and Nocardia 1

Common Pitfalls to Avoid

• Do not assume all diarrhea in IBD patients is a disease flare—always test for superimposed infections including C. difficile, CMV, and bacterial pathogens 1
• Do not escalate immunosuppression (e.g., starting infliximab or calcineurin inhibitors) when active infection is present or suspected 1
• Do not delay infectious disease consultation when managing complex cases with immunosuppression and active infection 1

When Surgical Consultation is Needed

Consider early surgical consultation for:

• Signs of perforation or peritonitis
• Toxic megacolon
• Severe systemic inflammation unresponsive to medical therapy
• Fulminant colitis with hemodynamic instability