Match each clinical presentation to the most appropriate, evidence-based therapeutic inter… — USMLE Step 2 CK

Match each clinical presentation to the most appropriate, evidence-based therapeutic intervention, taking into account current clinical guidelines and antimicrobial stewardship principles.

A 62-year-old man presents with voluminous watery diarrhea and abdominal cramping after a recent course of amoxicillin-clavulanate. His white blood cell count is $18,000/\mu L$ . Stool assay is positive for Clostridioides difficile.Oral fidaxomicin administration
A 24-year-old woman presents with dysuria and urinary frequency. Urinalysis confirms an uncomplicated lower urinary tract infection. Local resistance rates for Escherichia coli to trimethoprim-sulfamethoxazole exceed $20\%$ .Oral nitrofurantoin administration
A 28-year-old non-pregnant woman is diagnosed with primary syphilis after presenting with a painless genital chancre. She has a documented history of severe, IgE-mediated anaphylaxis to penicillins.Oral doxycycline administration
A 40-year-old immunocompetent man presents with a $3\text{ cm}$ fluctuant cutaneous abscess on his right thigh. He is afebrile and has no surrounding cellulitis or signs of systemic toxicity.Incision and drainage without antimicrobial therapy

Answer

The correct matches pair each specific infectious presentation with the management step that adheres to current antimicrobial stewardship guidelines: fidaxomicin for initial C. difficile, nitrofurantoin for cystitis with high TMP-SMX resistance, doxycycline for syphilis with penicillin anaphylaxis (non-pregnant), and simple incision and drainage for an uncomplicated abscess.

Each correct pairing reflects the current standard of care regarding infectious disease management and antimicrobial stewardship. Fidaxomicin targets C. difficile while reducing recurrence. Nitrofurantoin avoids empiric failure in areas of high TMP-SMX resistance. Doxycycline provides a safe, non-beta-lactam alternative for early syphilis in non-pregnant individuals. Incision and drainage without antibiotics prevents unnecessary antimicrobial exposure for simple abscesses.

Step-by-Step Solution

Analyze the Clostridioides difficile presentation.

Identify that current IDSA guidelines prioritize fidaxomicin (or oral vancomycin) over metronidazole for initial episodes.

Fidaxomicin provides a narrow spectrum that spares normal gut flora and significantly reduces recurrence rates.

Evaluate the uncomplicated cystitis scenario with local E. coli data.

Recognize that TMP-SMX should be avoided since resistance exceeds the

20\%

threshold.

Empiric therapy must have a high likelihood of success; nitrofurantoin or fosfomycin are preferred when TMP-SMX resistance is high.

Assess the treatment options for primary syphilis in the context of anaphylaxis.

Determine that oral doxycycline is the standard alternative therapy.

Because the patient is not pregnant, penicillin desensitization is unnecessary, and a 14-day course of doxycycline is highly effective.

Determine the necessity of antibiotics for the cutaneous abscess.

Conclude that no antibiotics are needed.

The patient is afebrile and immunocompetent with no systemic inflammatory signs, making incision and drainage alone the gold standard.

Key Concept

Targeted therapeutic interventions and antimicrobial stewardship in general internal medicine

Estimated Time:2m 0s

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