NYACP Board Review Question of the Week
Every other Tuesday, NYACP members are sent a Board Review Question from ACP's MKSAP 18 to test professional knowledge and help prepare for the exam. Participant totals and answer percentages are distributed on the first Thursday of the month in IM Connected, the Chapter's eNewsletter, and are also published on this page.
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August 12, 2025
MKSAP 19 Infectious Disease, Question 95
A 40-year-old man presents to the emergency department with a 2-day history of diarrhea occurring six times daily that developed 1 week after completing a course of amoxicillin-clavulanate for diverticulitis. Medical history is unremarkable, and he takes no medications.
On physical examination, temperature is 38.3 °C (100.9 °F); other vital signs are normal. Bowel sounds are present; palpation elicits tenderness but no guarding.
Laboratory studies show a leukocyte count of 17,000/µL (17 × 109/L) and serum creatinine level of 1.6 mg/dL (141 µmol/L).
Stool testing for Clostridioides difficile is positive.
Which of the following is the most appropriate treatment?
A. Intravenous metronidazole
B. Oral fidaxomicin
C. Oral vancomycin and rectal vancomycin
D. Tapered and pulsed vancomycin
Responses Received from Members (Graph is uploaded on Thursday afternoon):
The Correct Answer is: B. Oral fidaxomicin
Educational Objective:
Treat a first episode of severe Clostridioides difficile infection.
This patient has an initial episode of severe Clostridioides difficile infection (CDI), which should be treated with oral fidaxomicin therapy (Option B). Antibiotic use is the strongest risk factor for CDI. It is most highly associated with antimicrobial agents that have activity against anaerobic colonic flora but are not effective against C. difficile (such as clindamycin). Antibiotic-associated diarrhea in these cases is thought to occur by suppression of the intestinal microbiota, with resultant overgrowth of C. difficile organisms and production of toxin (toxins A and B). In all cases of CDI, the culprit antibiotic should be stopped if possible. All patients with confirmed CDI require antimicrobial treatment, but optimal management depends on whether the episode represents an initial infection or first or second recurrence and on the severity of disease (nonsevere, severe, fulminant). Severe CDI is defined by a leukocyte count of 15,000/µL (15 × 109/L) or greater or a serum creatinine level of 1.5 mg/dL (133 µmol/L) or greater. The 2021 Infectious Diseases Society of America and Society for Healthcare Epidemiology of America clinical practice guideline for CDI recommends either oral fidaxomicin (preferred) or oral vancomycin (alternative) for patients with nonsevere or severe CDI.
Intravenous metronidazole monotherapy (Option A) is not an indicated treatment for any degree of CDI severity or initial or recurrent disease status. Intravenous metronidazole therapy combined with oral vancomycin is an indicated regimen for fulminant CDI which is associated with hypotension, shock, ileus, or megacolon. Patients with fulminant disease also warrant surgical evaluation.
Another option for fulminant CDI infection is combined oral vancomycin, intravenous metronidazole, and rectal vancomycin when ileus is present (Option C). This patient does not have fulminant CDI; therefore, this combination therapy is not indicated.
Tapered and pulsed vancomycin therapy (Option D) consists of oral vancomycin, 125 mg four times daily for 10-14 days, then 125 mg twice daily for 7 days, then 125 mg once daily for 7 days, then 125 mg every 2 or 3 days for 2 to 8 weeks. Tapered and pulsed vancomycin therapy is an indicated therapeutic option for first and subsequent CDI recurrences if the initial episode was treated with standard therapy consisting of vancomycin or fidaxomicin.
Key Point
Severe CDI is defined by a leukocyte count of 15,000/µL (15 × 109/L) or greater or a serum creatinine level of 1.5 mg/dL (133 µmol/L) or greater.
Oral fidaxomicin or vancomycin is recommended to treat an initial episode of nonsevere or severe Clostridioides difficile infection.
Bibliography
Johnson S, Lavergne V, Skinner AM, et al. Clinical practice guideline by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA): 2021 focused update guidelines on management of Clostridioides difficile infection in adults. Clin Infect Dis. 2021;73:755- 757. PMID: 34492699 doi:10.1093/cid/ciab718
Copyright 2019, American College of Physicians.
July 29, 2025
MKSAP 19 Infectious Disease, Question 19
A 34-year-old woman is evaluated in the emergency department for a 3-day history of increasing urinary frequency, urgency, and burning accompanied by right flank pain, fever, chills, nausea, and vomiting. She was treated with trimethoprim-sulfamethoxazole for cystitis 2 weeks ago. Medical history is also significant for nephrolithiasis. Her only other medication is an oral contraceptive pill. She reports experiencing a rash with amoxicillin in childhood, but no adverse reactions to cephalosporin medications.
On physical examination, temperature is 38.9 °C (102 °F), blood pressure is 92/60 mm Hg, and pulse rate is 96/min. Palpation elicits right-sided costovertebral angle punch tenderness.
Urinalysis reveals cloudy urine with greater than 100 leukocytes/hpf, 0-5 erythrocytes/hpf, and 4+ bacteria. A urine pregnancy test is negative.
Bilateral, nonobstructing, small ureteral-pelvic junction calculi are seen on kidney ultrasound.
Which of the following is the most appropriate intravenous treatment?
A. Aztreonam
B. Ceftriaxone
C. Ciprofloxacin
D. Levofloxacin
Responses Received from Members (750 Responses):
The Correct Answer is: B. Ceftriaxone
Educational Objective:
Treat acute pyelonephritis.
Intravenous antimicrobial therapy with ceftriaxone (Option B) or another broad-spectrum cephalosporin or carbapenem would be appropriate initial treatment options in this patient who has complicated acute pyelonephritis. Urinary tract infections in men, pregnant women, and persons with foreign bodies (e.g., indwelling catheters, calculi), kidney disease, immunocompromise, obstruction, urinary retention from neurologic disorders, health care–associated infections, or recent antibiotic use are considered to be complicated. This patient requires hospitalization because of potential hemodynamic instability, inability to tolerate oral medication, and concern for pathogen resistance because of recent antimicrobial therapies. Urine and blood cultures should be performed as well. A detailed antibiotic allergy history regarding possible reactions to penicillin is required to determine the patient has no clear contraindication to these β-lactam medications and serves to avoid the use of other potentially less effective and more costly antimicrobial therapies.
The monobactam aztreonam (Option A) is safe to prescribe in persons with a known or suspected severe allergy to β-lactam antibiotics. However, this drug is unnecessary in a patient who reports having taken cephalosporin medications without a problem.
Empiric intravenous fluoroquinolones such as ciprofloxacin and levofloxacin (Option C, D) are not recommended as initial treatment in hospitalized patients with complicated pyelonephritis because of the increased rate of resistance in common uropathogens.
Trimethoprim-sulfamethoxazole (Option E) would not be an appropriate choice in this patient owing to high rates of community resistance and her recent exposure to this drug.
Active oral antibiotics can be substituted to complete therapy in clinically stable patients who have reliable follow up. Choices may include fluoroquinolones or trimethoprim-sulfamethoxazole. β-
Lactams (e.g., amoxicillin-clavulanate, cephalexin, cefdinir, cefpodoxime proxetil) are an alternative but may be less effective in eradication of the infection. Patients with bacteremia who exhibit adequate clinical responses do not require follow-up blood cultures or prolonged intravenous therapy.
Key Point
Intravenous antimicrobial therapy with ceftriaxone (or another broad-spectrum cephalosporin or carbapenem) is appropriate initial treatment in patients with complicated acute pyelonephritis who require hospitalization.
Empiric intravenous fluoroquinolones are not recommended for treatment of complicated pyelonephritis in hospitalized patients.
Bibliography
Johnson JR, Russo TA. Acute pyelonephritis in adults. N Engl J Med. 2018;378:48-59. PMID: 29298155
Copyright 2019, American College of Physicians.