What is the recommended treatment for Cytomegalovirus (CMV) colitis?

Treatment of CMV Colitis

Initiate intravenous ganciclovir 5 mg/kg twice daily for 3-5 days, then transition to oral valganciclovir 900 mg twice daily to complete a 2-3 week total course. 1, 2

Diagnostic Confirmation Before Treatment

• Obtain colonoscopy with multiple biopsies from ulcer bases and edges for histology and immunohistochemistry (IHC), as these locations have the highest densities of CMV-positive cells 1
• IHC is the gold standard diagnostic test with sensitivity of 78-93% and specificity of 92-100% 1
• Colonic tissue CMV DNA PCR improves diagnostic sensitivity, though a viral load cut-off of >250 viral copies/mg tissue is suggested to distinguish clinically significant infection 1
• Begin ganciclovir immediately when CMV colitis is suspected clinically or endoscopically, even before histopathologic confirmation, due to high mortality risk in severely immunocompromised patients 3

Standard Antiviral Regimen

• Start IV ganciclovir 5 mg/kg every 12 hours for 3-5 days as initial therapy 1, 3, 2
• Switch to oral valganciclovir 900 mg twice daily after the initial IV phase to complete a total 2-3 week course 1, 2
• For pediatric patients or severely immunodeficient patients (e.g., SCID), maintain parenteral ganciclovir for the full 14-21 day course rather than switching to oral therapy, as early transition may promote CMV reactivation 3
• Continue antiviral therapy until CMV is no longer detected in blood by PCR 3

Management of Immunosuppression

This is a critical decision point where guidelines provide nuanced recommendations:

• In inflammatory bowel disease (IBD) patients with CMV colitis, immunosuppressive therapy should not be discontinued in general 1
• Steroids should be tapered rather than abruptly stopped 1
• Antiviral therapy should be considered in steroid-refractory IBD patients with CMV colitis 1
• Many case series show that immunosuppressants are maintained for disease activity control in most cases, and CMV clearance may parallel remission achievement even without antivirals, particularly in patients with low viral load 1
• Discontinuation of immunosuppressive therapy is recommended only in symptomatic disseminated CMV infection (mononucleosis-like syndrome with fever, malaise, leukopenia, thrombocytopenia, elevated liver enzymes) 1
• Prompt antiviral treatment and temporary discontinuation of immunomodulators is associated with clinical improvement and decreased mortality in non-IBD contexts 1

Monitoring Requirements

• Check complete blood count at least twice weekly during ganciclovir therapy, as severe neutropenia occurs in approximately 11% of treated patients 3
• Obtain weekly CMV viral load by PCR to assess treatment response 3
• Monitor serum creatinine and electrolytes closely, particularly if foscarnet is required 3

Alternative Agents for Resistance or Intolerance

• Foscarnet 90 mg/kg IV every 12 hours (or 60 mg/kg every 8 hours) for 14-21 days is the primary alternative when ganciclovir resistance is documented or suspected 3, 4
• Foscarnet requires infusion over 1-2 hours with concurrent saline fluid loading (1 liter normal saline with each infusion) to prevent nephrotoxicity 4
• High-dose valganciclovir (1800 mg twice daily based on creatinine clearance) may be considered for ganciclovir-resistant CMV colitis when foscarnet causes acute kidney injury 5
• Cidofovir is reserved as a third-line agent due to substantial nephrotoxicity risk 3

Surgical Intervention Criteria

• Proceed urgently to subtotal or partial colectomy if the patient develops toxic megacolon, fulminant colitis, colonic perforation, or bowel ischemia despite antiviral therapy 3
• Obtain early surgical consultation on admission for severely immunocompromised patients given the extremely high mortality risk 3
• Antiviral treatment significantly improves surgery-free survival in UC patients with CMV colitis, with benefits lasting up to 70 months 6

Adjunctive Measures

• Add broad-spectrum antibiotics to the antiviral regimen, as bacterial translocation and secondary infection are common complications with bowel wall necrosis 3
• Consider infectious disease consultation early in the treatment course 1, 2

Critical Pitfalls to Avoid

• Do not delay antiviral therapy waiting for histopathologic confirmation in severely ill or immunocompromised patients 3
• Do not switch to oral therapy prematurely in children or severely immunodeficient patients 3
• Do not abruptly discontinue all immunosuppression in IBD patients with CMV colitis, as this may worsen the underlying inflammatory disease without clear benefit 1
• Recognize that CMV reactivation in IBD may be an innocent bystander in some cases, particularly with low viral loads, where immunosuppressant-induced remission can clear CMV without antivirals 1