NAPLEX Question of the Week: Gastrointestinal Difficulties

A major complication of antibiotic therapy is the subject of our question of the week!
NAPLEX Question of the Week: Gastrointestinal Difficulties

JT is a 45-year-old male who presents to the ED with complaints of severe abdominal discomfort and nausea. Additionally, JT mentions that he had 4 episodes of loose, watery stools in the past 24 hours. The patient’s PMH is significant for hypertension and diabetes. Current medications include Microzide 25mg daily, Janumet 50mg/500mg BID, and Protonix 40mg daily. Laboratory tests confirm a diagnosis of Clostridioides difficile infection (CDI). Of importance, the patient has no prior episodes of CDI.   

Pertinent Labs:  

  • Na: 137, K: 3.6, Cl: 97, BUN: 15, WBC: 14.3K, Scr: 1.4 mg/dL, Glucose: 100 mg/dL
  • Glutamate dehydrogenase (GDH) antigen: positive  
  • Toxin assay: positive  
  • Vitals: BP: 130/76 mm Hg, HR 98, RR 13, Temp 100.3 F 
  • Weight – 85kg    Height 67 inches 

Allergies: Penicillin (rash), Macrolides (anaphylaxis) 

Which of the following would be appropriate options to help manage this patient? Select all that apply. 

A. Vancomycin 125mg PO QID X 10 days

B. Fidaxomicin 200mg IV Q12H x 10 days

C. Vancomycin 125mg IV QID x 10 days 

D. Fecal microbiota transplant

E. Discontinue Protonix therapy

F. Metronidazole 250mg PO TID X 10 days

G. Fidaxomicin 200mg PO BID x 10 days

Answer with rationale: A, E  

Brand/Generics covered: Microzide (hydrochlorothiazide), Janumet (sitagliptin-metformin), and Protonix (pantoprazole) 

Explanation: 

Clostridioides difficile is a gram-positive, anaerobic bacillus that can cause an infection of the large intestine leading to severe diarrhea and colitis. C. difficile is considered a major health threat causing approximately half a million infections yearly. While symptoms of CDI can be non-specific, CDI typically presents as foul-smelling, watery stools, abdominal pain, fever, and leukocytosis. Major risk factors for CDI include antibiotic exposure, advanced age, female gender, duration of stay in healthcare settings, use of proton pump inhibitors, weakened immune system, and previous CDI.  

The Infectious Diseases Society of America (IDSA) Guidelines on the management of CDI provide recommendations for the treatment of CDI in adults based on the number of times infected (initial episode, first recurrence, second/subsequent recurrence) and severity (non-severe, severe, fulminant). JT presents to the ED for treatment for an initial episode of CDI. Additionally, JT’s initial episode is classified as non-severe. Non-severe CDI is defined as leukocytosis with WBC < 15,000 cells/mL AND SCr < 1.5 mg/dL. 

For an initial episode of non-severe CDI, fidaxomicin 200mg PO BID X 10 days is preferred. Vancomycin 125mg PO QID X 10 days serves as an alternative first-line treatment, making answer A correct. If fidaxomicin and vancomycin are both unavailable, metronidazole 500mg PO TID X 10-14 days is acceptable but would not be appropriate for a severe case of CDI as it has been shown to have worse outcomes compared to oral vancomycin.  

Answer choice B is incorrect because the patient has a severe macrolide allergy. It is important to note that fidaxomicin, like azithromycin, erythromycin and clarithromycin is a macrolide antibiotic. Additionally, this answer choice is incorrect because fidaxomicin is an oral antibiotic.  

Answer choice C is incorrect because IV vancomycin is not effective in the management of CDI. 

Answer choice D is incorrect. The guideline panel recommends that appropriate antibiotic treatments for 3 CDI episodes should be tried prior to offering fecal microbiota transplantation. This is JT’s initial episode and should be treated with appropriate antibiotics first.  

Answer choice E is correct. Our patient does not have any history of GERD/PUD and therefore no documented indication for Protonix. Therefore stopping the PPI would be appropriate to help overall CDI treatment and possibly decrease future recurrence. 

Answer F is incorrect as metronidazole is not a first-line option for CDI management. In addition, the dosing is incorrect at 250mg PO TID as the recommended dose is 500mg TID if flagyl must be used. 

Answer choice G is incorrect. Although this answer choice lists the correct dose, route, frequency, and duration of fidaxomicin, the use of fidaxomicin would be inappropriate in this patient due to the macrolide allergy.   

NAPLEX Competencies Covered: Area 1 (Obtain, Interpret, or Assess Data, Medical or Patient Information), 1.5 Signs and symptoms of medical conditions, health physiology, etiology of diseases or pathophysiology; 1.6 Risk factors or maintenance of health and wellness; Area 2 (Identify Drug Characteristics), 2.1 Pharmacology, mechanism of action, or therapeutic class; 2.2 Commercial availability; prescription or non-prescription status; brand, generic, or biosimilar names; physical descriptions; or how supplied; Area 3 (Develop or Manage Treatment Plans), drug dosing or dosing adjustments; duration of therapy; 3.6 drug contraindications, allergies, or precautions.  

Keep up the hard work as many of you are in final preparation for taking the NAPLEX!

Sincerely,

Dr. B