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Difficulty: MediumPediatric Infectious Diseases

A preschool-aged child is admitted to the pediatric ward due to restricted neck movement, high fevers, and a progressively enlarging left-sided neck mass. Admission imaging confirms a four-centimeter complex fluid collection with surrounding soft tissue inflammation, consistent with acute suppurative cervical lymphadenitis. The patient is empirically started on intravenous vancomycin and ceftriaxone. An ultrasound-guided aspiration is performed, yielding purulent material. The bacterial culture of the aspirate grows Staphylococcus aureus. The susceptibility report indicates the pathogen is susceptible to methicillin, oxacillin, and cefazolin, but resistant to penicillin. By the third day of hospitalization, the child has been afebrile for over forty-eight hours, the localized cervical swelling has markedly decreased, and oral intake has returned to baseline. The medical team is preparing the patient for discharge to complete a fourteen-day course of oral antibiotics at home. Which of the following is the most appropriate outpatient pharmacotherapy?

  1. CephalexinAnswer
  2. B
    Amoxicillin-clavulanate
  3. C
    Trimethoprim-sulfamethoxazole
  4. D
    Linezolid
  5. E
    Amoxicillin

Answer

Cephalexin
Cephalexin is a narrow-spectrum, first-generation cephalosporin that provides excellent, targeted Gram-positive coverage. The culture results explicitly indicate a methicillin-susceptible Staphylococcus aureus (MSSA) isolate, which is evidenced by its susceptibility to oxacillin and cefazolin. For confirmed MSSA infections, beta-lactam antibiotics (such as first-generation cephalosporins or anti-staphylococcal penicillins like dicloxacillin) are the superior agents of choice due to their potent bactericidal activity and favorable safety profile. Transitioning a clinically improved, afebrile patient to oral cephalexin represents ideal antibiotic stewardship by narrowing the spectrum of coverage while ensuring therapeutic efficacy.

Step-by-Step Solution

1
Analyze the clinical scenario and culture results.
The patient has improving acute suppurative cervical lymphadenitis caused by methicillin-susceptible Staphylococcus aureus (MSSA), as evidenced by susceptibility to oxacillin and cefazolin.
Accurate interpretation of the culture data determines the appropriate therapeutic target for step-down therapy.
2
Evaluate the patient's readiness for hospital discharge and care transition.
The patient has been afebrile for >48 hours, swelling has receded, and oral intake is normal, making them an excellent candidate for oral step-down therapy.
Confirms that transitioning from intravenous to oral antibiotics is clinically indicated and safe.
3
Apply principles of antibiotic stewardship to select the optimal oral agent.
Select a narrow-spectrum beta-lactam agent with high efficacy against MSSA, such as cephalexin.
Narrowing the antibiotic spectrum minimizes collateral damage to normal flora and prevents the emergence of broad-spectrum antimicrobial resistance.

Key Concept

Appropriate step-down oral antibiotic therapy and stewardship for pediatric methicillin-susceptible Staphylococcus aureus (MSSA) infections.
Estimated Time:1m 15s
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Topics

Pediatric Infectious Diseases

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