Critical Care Medicine-Infections and Immunologic Disease>>>>>Gastrointestinal and Intra-abdominal Infections
Question 2#

A 68-year-old woman has been in the ICU for 5 days receiving ceftazidime for Pseudomonas aeruginosa meningitis following surgical removal of a meningioma. This morning on rounds her nurse mentions that the patient had three loose stools overnight. Laboratory results show that the patient’s white blood cell count jumped from 7,600 to 16,500 cells/µL. Serum creatinine has also increased from 1.2 to 1.9 mg/dL. Nucleic acid amplification test and stool toxin test are both positive for Clostridium difficile.

What is the recommended management?

A. Metronidazole 500 mg PO three times daily for 10 days
B. Vancomycin 125 mg PO four times daily or fidaxomicin 200 mg PO twice daily for 10 days
C. Repeat testing for C. difficile toxin at 14 days
D. Both A and C
E. Both B and C

Correct Answer is B


Correct Answer: B

All antibiotics, including vancomycin and metronidazole, carry a risk for C. difficile infection (CDI); however, clindamycin, ampicillin, cephalosporins, and fluoroquinolones are associated with the majority of infections. Patients with three or more new, unexplained loose stools in 24 hours should be tested for CDI. All patients with suspected CDI should be placed on contact precautions pending test results and, if positive, these precautions should be continued for at least 48 hours after diarrhea has resolved. Nucleic acid amplification testing, either alone or as part of an algorithm including initial enzyme immunoassay screening for glutamate dehydrogenase antigen and toxins A and B, is now the preferred diagnostic test. Vancomycin or fidaxomicin PO are the recommended antibiotics for the initial episode of both severe and nonsevere disease; however, metronidazole can be used for nonsevere disease if access to oral vancomycin or fidaxomicin is limited. This patient has severe disease based on a leukocytosis of >15,000 cells/µL and serum creatinine >1.5 mg/dL. Repeat testing following resolution of diarrhea is not indicated because >50% of patients will continue to harbor both the organism and toxin. 


  1. Gerding DN, Johnson S. Clostridium difficile infection, including Pseudomembranous colitis. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J, eds. Harrison’s Principles of Internal Medicine. 19 ed. New York, NY: McGraw-Hill; 2014.
  2. McDonald LC, Gerding DN, Johnson S, et al. Clinical practice guidelines for Clostridium difficile infection in adults and children: 2017 update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA). Clin Infect Dis. 2018;66(7):e1-e48.