Community-acquired Lobar Pneumonia in Medicine / Internal Medicine — 45yo Man | Infectious Diseases | SMLE Q#19036

A 45-year-old man is admitted with community-acquired lobar pneumonia. He has 3 days of productive cough, pleuritic chest pain, and fever. Chest radiograph shows right lower-lobe consolidation. He is started on IV ceftriaxone plus azithromycin; he also receives paracetamol and tramadol for pain/fever. After 24 hours, his fever improves and he is hemodynamically stable. Vital signs: T 37.6°C, BP 122/76 mmHg, HR 88/min, RR 18/min, SpO2 96% on room air. Lab results (baseline on admission  24 h later): - Platelets: 210  70  ^9/L - Hemoglobin: 14.2 g/dL - WBC: 13.8 ^9/L - Creatinine: 0.9 mg/dL - AST/ALT: 24/28 U/L He has no petechiae or active bleeding. Which medication is the most likely cause of this acute thrombocytopenia and should be stopped?