Review Question - QID 220788

This patient who presents with a productive cough and fever in the setting of chronic alcohol use disorder most likely has aspiration pneumonia that was treated with antibiotics. He then developed profuse watery diarrhea and lower abdominal tenderness, suggestive of Clostridioides difficile (C. diff) infection, which can be treated with oral vancomycin.

C. diff infection can be caused by the use of any antibiotics. The most common culprits are clindamycin, fluoroquinolones, cephalosporins, and penicillins. Antibiotic usage disrupts the gut microbiota, permitting C. diff spores to colonize the gut and produce toxins which cause watery diarrhea. Diagnosis is confirmed with either nucleic acid amplification testing for the C. diff toxin gene or stool toxin assay. The treatment for an initial episode of non-severe C. diff infection is oral fidaxomicin or oral vancomycin. Given the high cost of fidaxomicin, oral vancomycin is often used in practice when fidaxomicin is unavailable or infeasible.

Johnson et al. review the evidence regarding the management of C. diff infection. They discuss how fidaxomicin is the most effective agent for C. diff infections. They recommend considering other agents such as vancomycin or metronidazole, given the high cost and limited availability of fidaxomicin.

Figure/Illustration A is a chest radiograph that demonstrates infiltrates in the right lower lobe of the lung (red circle). These findings are consistent with aspiration pneumonia.

Incorrect Answers:
Answer 1: Oral dexamethasone is a corticosteroid that is used in the treatment of inflammatory bowel disease (IBD) flares. IBD consists of Crohn disease or ulcerative colitis and causes inflammatory diarrhea which is bloody. This patient’s diarrhea is watery and occurs in association with recent antibiotic use, which is indicative of C. diff infection.

Answer 2: Oral loperamide is an anti-diarrheal agent used in the management of irritable bowel syndrome (IBS), diarrheal subtype. IBS is diagnosed according to the Rome criteria, which requires at least 2 of the following: abdominal pain that is related to defecation, a change in stool frequency, or a change in stool appearance. It is not diagnosed when an organic cause is present.

Answer 4: Parenteral azithromycin can be used in the treatment of Shigella or Salmonella causing infectious diarrhea. This would present with bloody diarrhea rather than watery diarrhea. Patients also tend to have a higher fever and more abdominal distress.

Answer 5: Parenteral vancomycin is used as empiric broad-spectrum antibiotic treatment for a wide range of diseases like sepsis. However, oral, not parenteral, vancomycin is used in the treatment of C. diff infections that occur within the gut lumen. Parenteral vancomycin is commonly used in the treatment of methicillin-resistant Staphylococcus aureus.

Bullet Summary:
The initial treatment for C. difficile infection is fidaxomicin or oral vancomycin.