A 35-year-old otherwise healthy man presents to his GP with 3 days of productive cough, pleuritic chest pain and fever. Temperature is 38.3°C, heart rate 92 beats/min, blood pressure 120/70 mmHg, respiratory rate 20 breaths/min and oxygen saturation 97% on room air. Chest examination reveals crackles over the right lower zone. He is stable and suitable for outpatient treatment of mild community-acquired pneumonia. Which is the most appropriate first-line oral antibiotic regimen?