A 4-year-old child admitted to hospital with history of high fever, cough, and tachypnea; chest radiograph reveals lobar pneumonia treated with I.V. ceftriaxone with partial response; 7 days later, the fever recurs with toxicity, new chest radiograph reveals cavitary lesion with an air-fluid level. Of the following, the BEST management is

Correct Answer: D

Rationale: Necrotizing pneumonia with cavitation suggests S. aureus or anaerobes; adding clindamycin (D) targets these, per IDSA guidelines.

Correct Answer: B

Rationale: Stool culture is indicated for fever (A), traveler’s (C), C. diff (D), and HUS (E). Profuse diarrhea (B) alone doesn’t necessitate it, per guidelines.

Correct Answer: C

Rationale: Prothrombin time (C) reflects liver synthetic function and predicts fulminant failure, per hepatology.

Correct Answer: C

Rationale: Leukocyturia ≥10 WBCs/mm³ (C) suggests UTI, per diagnostic thresholds.

Correct Answer: A

Rationale: Sequestra (A), dead bone fragments, are the radiologic hallmark of chronic osteomyelitis, per imaging.