A 74-year-old woman is brought to the emergency department from a skilled nursing facility due to a positive stool PCR test for Clostridioides difficile. The patient was discharged from the hospital to the nursing facility 10 days ago after treatment for urinary tract infection and septic shock. She developed C difficile-associated diarrhea during the hospitalization and completed a course of oral fidaxomicin therapy 3 days ago. This treatment resolved the diarrhea, nausea, and abdominal pain; yesterday, the patient had an episode of bloating, nausea, and loose stool after a meal at the nursing facility, prompting repeat stool testing. Since then, she has had no additional abdominal pain, nausea, vomiting, or diarrhea. Other medical conditions include hypertension, hyperlipidemia, ischemic stroke with residual left hemiparesis, and gastroesophageal reflux. Temperature is 37 C (98.6 F) , blood pressure is 130/68 mm Hg, and pulse is 84/min. The abdomen is soft, nondistended, and nontender, with normoactive bowel sounds in all quadrants. Rectal examination shows soft, brown stool negative for occult blood. Leukocyte count is 7,100/mm³.
Which of the following is the most appropriate course of action in management of this patient's symptoms?

Question

Quizplus · Accepted Answer

Explanation: Clostridioides difficile is a gram-positive, spore-forming bacterium transmitted via the fecal-oral route. Nontoxigenic strains are typically benign, but toxigenic strains can cause colitis in susceptible patients (eg, hospitalized, elderly, recent antibiotic users). The diagnosis of C difficile-associated diarrhea (CDAD) requires both of the following: Characteristic symptoms: Watery diarrhea (≥3 loose stools in 24 hr) is the hallmark symptom of C difficile infection; other classic symptoms include lower abdominal pain, low-grade fever, and leukocytosis. Positive stool testing for toxigenic C difficile: When characteristic symptoms are present, a positive test generally represents active infection (vs carrier status). Treatment with 10 days of oral fidaxomicin or vancomycin is generally curative, but recurrence occurs within 30 days of antibiotic cessation in approximately 25% of patients. Recurrence is marked by the reemergence of characteristic symptoms with positive C difficile stool testing. This patient's single episode of loose stool does not qualify as a CDAD symptom (≥3 loose stools in 24 hr) and could have many causes (eg, food intolerance). Although PCR testing for C difficile was positive, stool testing may remain positive for days to weeks after treatment; this is particularly true for PCR, which tests for the toxin-producing gene, not the toxin itself. A positive PCR alone is insufficient to diagnose recurrence. Therefore, this patient should be observed; antibiotic therapy is not indicated at this time (Choice E). (Choice B) Enzyme immunoassays for toxins A and B detect active toxin production and can therefore be more specific than PCR for detecting active infection (vs carrier status). However, further stool testing is not indicated in this patient given the absence of characteristic CDAD symptoms. (Choice C) Sigmoidoscopy with biopsy is an invasive procedure and is not indicated in this patient for a single episode of loose stool. In patients with ongoing CDAD, sigmoidoscopy is generally avoided due to the risk for perforation but is sometimes used to aid in the diagnosis of fulminant colitis when diarrhea is absent. (Choice D) With drug-resistant strains of C difficile, symptoms are likely to worsen or continue during treatment. This patient's condition clinically improved with fidaxomicin, making drug resistance unlikely. When CDAD recurs, it is commonly due to the persistence of spores or reinfection by exogenous C difficile rather than drug resistance. Educational objective: The diagnosis of Clostridioides difficile-associated diarrhea requires the presence of characteristic symptoms (eg, watery diarrhea, abdominal pain, leukocytosis) in addition to positive stool testing for C difficile. References: ACG clinical guidelines: prevention, diagnosis, and treatment of Clostridioides difficile infections. (http://www.ncbi.nlm.nih.gov/pubmed/34003176) Current knowledge on the laboratory diagnosis of Clostridium difficile infection. (http://www.ncbi.nlm.nih.gov/pubmed/28321156)

A 74-Year-Old Woman Is Brought to the Emergency Department from a Skilled