Diagnosing C. difficile Infection in Cancer Patients Undergoing Chemoradiation

Risk Factors and Context

Cancer patients receiving chemoradiation are at increased risk for C. difficile infection due to disruption of gastrointestinal microflora from both chemotherapy and antibiotics 3, 4
In cancer patients with diarrhea, C. difficile overgrowth occurs in 7-50% of cases following antibiotic administration 3
While chemotherapy toxicity is the most common cause of diarrhea in cancer patients, infectious causes must always be ruled out before symptomatic management 5, 3

Evaluate diarrhea severity, duration, and associated symptoms (fever, abdominal pain, blood in stool) 6, 2
Assess for risk factors: recent antibiotic use, hospitalization, immunosuppression from cancer treatment 3, 1
Check for warning signs of complicated diarrhea: fever, neutropenia, dehydration, severe cramping 7, 6

Primary C. difficile testing should use a two-step approach with enzyme immunoassays (EIAs) for glutamate dehydrogenase and toxins A/B, or nucleic acid amplification tests, as recommended by most guidelines 1, 2
Complete blood count to assess for neutropenia and leukocytosis 2
Electrolytes, creatinine, and BUN to evaluate hydration status 2
Blood cultures if fever is present (minimum two sets including from any indwelling catheters) 2

Test for other enteric pathogens: Salmonella, Shigella, Campylobacter, Yersinia 9, 8
Consider viral causes: adenovirus, astrovirus, CMV, norovirus, rotavirus 9
Evaluate for parasitic infections 9, 8
Consider lactose breath test for chemotherapy-associated lactose intolerance 3, 9

Neutropenic patients may not develop typical pseudomembranes on endoscopy as their formation requires neutrophils 1
In patients with persistent symptoms despite negative initial testing, repeat C. difficile testing may be warranted 9
Colonoscopy is generally not recommended in neutropenic patients due to increased risk of perforation 1

Confirmation of C. difficile infection will guide appropriate antimicrobial therapy 8
If C. difficile is ruled out, treatment for non-infectious diarrhea can be initiated with loperamide 5, 10
For loperamide-refractory cases, octreotide may be considered after infectious causes are excluded 10
Patients with complicated diarrhea may require IV fluids, antibiotics, and possibly hospitalization 7, 6