Delayed Diagnosis of Clostridium difficile Colitis in a 48-Year-Old Woman with a Homozygous Mutation of the UGT1A1 Gene While on Chemotherapy for Colorectal Carcinoma.

BACKGROUND There are many causes of chronic colitis and diarrhea, including the effects of chemotherapy. Mutations in the UGT1A1 gene can be associated with increased toxicity from irinotecan-based chemotherapy. This report is of a case of delayed diagnosis of Clostridium difficile (C. difficile) colitis in a 48-year-old woman with a homozygous mutation of the UGT1A1 gene treated with chemotherapy for colorectal carcinoma. CASE REPORT A 48-year-old woman with a low-differentiated colonic adenocarcinoma was treated after surgery with irinotecan, 5 fluorouracil, and panitumumab and had a history of chronic and severe diarrhea. Genetic testing identified a mutation in the UGT1A1 gene associated with increased toxicity to irinotecan, and the EIA tests performed for evaluation of C. difficile toxins A and B showed repeatedly negative results. Replacement of irinotecan with oxaliplatin did not have significant therapeutic results, but these were achieved by the administration of active antibiotics against C. difficile (metronidazole, vancomycin, and fidaxomicin). CONCLUSIONS This report has shown that in complex cases where patients are treated with chemotherapy and have increased susceptibility to drug toxicity, chronic diarrhea may still have an infectious cause. Only when the diagnosis is correctly made can the patient be appropriately treated.