WBR0888

Author	[[PageAuthor::Ayokunle Olubaniyi, M.B,B.S [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Inpatient Facilities
Sub Category	SubCategory::Infectious Disease
Prompt	[[Prompt::A healthy 70-year-old man with a past medical history of prostatectomy five years ago is being conservatively treated for perianal abscess. He is on intravenous ciprofloxacin, and he is gradually getting better. On the third day on admission, he suddenly develops lower abdominal pain and watery diarrhea. He denies any nausea or vomiting. Vital signs reveals a temperature of 38 deg Celsius, pulse rate of 101/min, respiratory rate of 22/min and a blood pressure of 100/70 mmHg. Examination reveals an elderly man, mildly dehydrated with a mild lower abdominal pain on deep palpation. Laboratory investigations reveal an elevated white blood cell count of 11,000/cm3 and sigmoidoscopy done reveals the image below: Which of the following is the treatment of choice for this patient?]]
Answer A	AnswerA::Oral metronidazole
Answer A Explanation	AnswerAExp::Oral metronidazole is the initial therapy for mild cases of the disease.
Answer B	AnswerB::Intravenous vancomycin
Answer B Explanation	AnswerBExp::There is no place for intravenous vancomycin in the treatment of this condition.
Answer C	AnswerC::Oral fidoxomicin
Answer C Explanation	AnswerCExp::This is reserved for cases of recurrence. Fidoxomicin has been proven to have a lower recurrence rates than vancomycin.
Answer D	AnswerD::Oral vancomycin
Answer D Explanation	[[AnswerDExp::This is reserved for severe cases, and also for those who experienced a relapse after a course of metronidazole treatment. The use of vancomycin is limited due its expensive cost, and also the risk of developing vancomycin-resistant enterococci (VRE).]]
Answer E	AnswerE::Oral rifaximin
Answer E Explanation	AnswerEExp::This is beneficial in the treatment of recurrent C. diff infections (CDI).
Right Answer	RightAnswer::A
Explanation	[[Explanation::This is a case of antibiotic-associated colitis or otherwise called pseudo-membranous colitis. Pseudomembranous colitis is an infection of the colon often caused by the bacterium Clostridium difficile. It is characterized by offensive-smelling watery diarrhea, fever, and abdominal pain. It can be severe, causing toxic megacolon, or even fatal. The Clostridium difficile bacteria are normally seen in the intestine. However, it may overgrow when you take antibiotics. The bacteria release a powerful toxin that causes the lining of the colon to become inflamed and bleed. The image shown above reveals the presence of pseudomembranes. The most common antibiotics associated with this condition are penicillin, clindamycin, fluoroquinolones, and cephalosporins (broad spectrum). Other antibiotics implicated are macrolides, trimethoprim, sulphonamides, and rarely implicated drugs such as aminoglycosides, tetracyclines, metronidazole and vancomycin. Pseudomembranous colitis is rare in infants younger than 12 months old and uncommon in children. It is most often seen in hospitalized patients on prolonged antibiotic treatment. However, it can also be community acquired. The initial step in management involves discontinuing the offending antibiotic agent and placing the patient on contact precaution. Oral metronidazole 500mg three times daily for 10-14 days is recommended for the treatment of mild forms of the disease i.e., with a WBC count of less than 15,000/cm3, temperature <38.5C, a creatinine less than 1.5 times of the normal. Oral vancomycin is usually reserved for the severe forms. There is no place for intravenous vancomycin in the treatment of pseudomembranous colitis since the drug is not excreted into the colon in appreciable quantity. Alternative drugs include fidoxomicin, which has a lower recurrence rate compared with vancomycin, and rifaximin. Educational Objective: Oral metronidazole remains the first line of therapy for antibiotic-associated clostridium difficile infection, and also in cases of relapse. Oral vancomycin is usually reserved for severe cases of primary infection and subsequent relapses. Other choices of medication in situations of recurrence are fidoxomicin and rifaximin. References: http://www.wikidoc.org/index.php/Pseudomembranous_colitis]]
Approved	Approved::No
Keyword	WBRKeyword::Pseudomembranous colitis, WBRKeyword::antibiotic-associated colitis, WBRKeyword::Clostridium difficile infrection
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