A 62-year-old man comes to the office for follow-up after recent hospitalization. Two weeks ago, the patient went to the emergency department due to a 3-day history of fever, chills, dysuria, urinary frequency, and low back pain. Evaluation showed a tender and swollen prostate, leukocytosis, pyuria, and bacteriuria. Treatment for acute bacterial prostatitis was begun with intravenous antibiotics. Blood and urine cultures returned positive for Escherichia coli sensitive to all tested antibiotics. The patient was discharged after clinical improvement and was prescribed oral ciprofloxacin. He has had no fever, and urinary symptoms have resolved, but over the last 2 days, he has had mild abdominal cramps and 4 or 5 watery bowel movements per day with no blood or mucus. Other medical conditions include hypertension and type 2 diabetes mellitus. On examination, the patient is afebrile, and other vital signs are within normal limits. There is mild periumbilical tenderness, but physical examination is otherwise unremarkable. Laboratory studies show a leukocyte count of 14,500/mm³ and serum creatinine level of 0.9 mg/dL. Stool testing is positive for Clostridioides difficile.
The patient returns to the office 3 weeks later and says that he took oral fidaxomicin as prescribed but stopped a week ago after the abdominal cramps and diarrhea improved. Since yesterday, he has had intermittent lower abdominal discomfort and several episodes of watery bowel movements. The patient reports no urinary symptoms and continues to take trimethoprim-sulfamethoxazole for the prostatitis. Temperature is 37.2 C (99 F) , blood pressure is 122/80 mm Hg, and pulse is 85/min. Physical examination shows mild tenderness in the left lower quadrant with no guarding or rebound tenderness and normal bowel sounds. Laboratory studies show a leukocyte count of 14,300/mm³. Which of the following is the most likely cause of this patient's symptoms?

Question

Quizplus · Accepted Answer

Explanation: This patient most likely has recurrent Clostridioides difficileinfection (CDI). Recurrence of CDI is common, affecting approximately 15%-30% of patients whose infection initially responds to antimicrobial therapy. The risk is particularly increased in patients taking prolonged antibiotics for other conditions, such as this patient taking continued therapy (eg, trimethoprim-sulfamethoxazole) for prostatitis. When CDI recurs, it is usually due to persistent spores from the initial infection rather than from drug resistance or infection with a new strain (Choice D). C difficile spores are hardy and antibiotic resistant. Spores that survive the initial course of antimicrobial therapy can germinate into fully functional bacilli in the colon and proliferate. Especially when normal colonic flora is continuously disrupted (eg, continued antibiotic use), the C difficile bacilli can overgrow, leading to recurrent symptoms. To reduce the risk of recurrence, treatment for CDI is often extended throughout the course of other antibiotic therapies. (Choice A) Acute sigmoid diverticulitis can present with left lower quadrant tenderness and diarrhea; however, it also commonly causes fever, nausea, and/or vomiting. In addition, diverticulitis is less likely because of this patient's recent use of antibiotics, including trimethoprim-sulfamethoxazole, which is often used (typically with metronidazole) in the outpatient treatment of diverticulitis. (Choice B) Postinfectious irritable bowel syndrome (IBS), which can occur after gastrointestinal infection, affects up to 10% of patients following successful treatment of CDI. It can present with changes in stool frequency or consistency (eg, diarrhea) and abdominal discomfort, but leukocytosis is much less common than in CDI. In addition, relief of pain with defecation is commonly reported and abdominal examination is usually normal. (Choice E) Small intestinal bacterial overgrowth (SIBO) can cause abdominal discomfort and watery diarrhea. However, bloating and flatulence are also commonly present, and leukocytosis is unexpected. In addition, abdominal examination is usually normal in patients with SIBO (vs left lower quadrant tenderness in this patient). Educational objective: Recurrence of Clostridioides difficile infection is common, especially in patients on prolonged antibiotics for other conditions. Recurrence is typically due to germination of persistent spores from the initial infection. To reduce the risk of recurrence, treatment for CDI is often extended throughout the course of other antibiotic therapies. References: ACG clinical treatment guidelines: prevention, diagnosis, and treatment of Clostridioides difficile infections. (http://www.ncbi.nlm.nih.gov/pubmed/34003176) Recurrent Clostridium difficile infection: risk factors, treatment, and prevention. (http://www.ncbi.nlm.nih.gov/pubmed/30400734)

A 62-Year-Old Man Comes to the Office for Follow-Up After