WBR0947
| Author | PageAuthor::William J Gibson |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Oncology, SubCategory::Infectious Disease |
| Prompt | [[Prompt::A 75-year-old woman undergoes total body irradiation followed by autologous bone marrow transplant for Chronic Lymphocytic Leukemia. 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?]] |
| Answer A | AnswerA::Metronidazole |
| Answer A Explanation | AnswerAExp::'''Incorrect:''' 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::'''Correct:''' Ganciclovir is a guanosine analogue that is converted to the active anti-metabolite by a virally encoded kinase. It is used for the treatment of CMV infections. |
| Answer C | AnswerC::Vancomycin |
| Answer C Explanation | AnswerCExp::'''Incorrect:''' 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::Incorrect: Cyclophosphamide is an immunosuppressive agent used for prophylaxis against graft-versus-host-disease (GVHD). While GVHD can manifest as early as one month after transplant and cause damage to the gastrointestinal tract, the clinical scenario strongly suggests CMV colitis. Furthermore, we one may be assured of an infectious etiology by the mention of pp65 antigen.]] |
| Answer E | AnswerE::Acyclovir |
| Answer E Explanation | AnswerEExp::'''Incorrect:''' While acyclovir shares a similar mechanism of action to ganciclovir, acyclovir is ineffective for CMV colitis 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, from the esophagus to the colon. The diagnosis of CMV colitis is based on serology, CMV antigen testing (pp65 antigen) and colonscopy with biopsy. CMV colitis should be treated with ganciclovir, a guanosine analogue that is converted to the active anti-metabolite by a virally encoded kinase.
Educational Objective: CMV colitis should be treated with ganciclovir, a guanosine analogue that is converted to the active anti-metabolite by a virally encoded kinase. References: First Aid 2013 page 188 (Ganciclovir) |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::CMV, WBRKeyword::Bone marrow transplantation, WBRKeyword::Cancer, WBRKeyword::Leukemia, WBRKeyword::Ulcer, WBRKeyword::Graft, WBRKeyword::Transplant, WBRKeyword::CLL, WBRKeyword::Chronic lymphocytic leukemia |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |