WBR0947

Author	[[PageAuthor::William J Gibson (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Infectious Disease
Prompt	[[Prompt::A 62-year-old woman undergoes total body irradiation followed by autologous bone marrow transplant for Chronic Lymphocytic Leukemia (CLL). Approximately one month following her transplant, she develops bloody stools, diarrhea, fever, abdominal pain, and dysphagia. Colonoscopy reveals several ulcers, and pp65 antigen assay is positive. Which of the following treatments is most appropriate to treat this patient's condition?]]
Answer A	AnswerA::Metronidazole
Answer A Explanation	[[AnswerAExp::Metronidazole would be the appropriate treatment for Clostridium difficile colitis. This patient is suffering from CMV colitis.]]
Answer B	AnswerB::Ganciclovir
Answer B Explanation	[[AnswerBExp::Ganciclovir is a guanosine analogue that is converted to its active anti-metabolite by a virally encoded kinase. It is indicated for the treatment of CMV infections.]]
Answer C	AnswerC::Vancomycin
Answer C Explanation	[[AnswerCExp::Oral vancomycin would be an appropriate treatment for Clostridium difficile colitis. This patient is suffering from CMV colitis.]]
Answer D	AnswerD::Cyclosporine
Answer D Explanation	[[AnswerDExp::Cyclosporine is an immunosuppressive agent used for prophylaxis against graft-versus-host-disease (GVHD). While GVHD can manifest as early as one month following transplant and cause damage to the gastrointestinal tract, the clinical features strongly suggest CMV colitis.]]
Answer E	AnswerE::Acyclovir
Answer E Explanation	[[AnswerEExp::While acyclovir shares a similar mechanism of action to ganciclovir, acyclovir is not effective to treat CMV infections because CMV does not contain a thymidine kinase.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient in this vignette is suffering from cytomegalovirus (CMV)-associated colitis. CMV colitis is associated with ulcerating lesions that may occur throughout the entire digestive tract. The diagnosis of CMV colitis is based on serology, CMV antigen testing (pp65 antigen) and colonoscopy with biopsy. CMV colitis should be treated with ganciclovir, a guanosine analogue that is converted to its active anti-metabolite by a virally encoded kinase. Educational Objective: CMV colitis should be treated with ganciclovir, a guanosine analogue that is converted to its active anti-metabolite by a virally encoded kinase. References: First Aid 2015 page 193.]]
Approved	Approved::Yes
Keyword	WBRKeyword::CMV, WBRKeyword::Cytomegalovirus, WBRKeyword::Bone marrow transplantation, WBRKeyword::BMT, WBRKeyword::Cancer, WBRKeyword::Leukemia, WBRKeyword::Ulcer, WBRKeyword::Graft, WBRKeyword::Transplant, WBRKeyword::CLL, WBRKeyword::Chronic lymphocytic leukemia
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