A 45-year-old otherwise healthy man presents to his GP with 3 days of fever, productive cough with green sputum and right-sided pleuritic chest pain. Temperature is 38.4 °C, respiratory rate 22/min, heart rate 96/min, blood pressure 125/75 mmHg and oxygen saturation 96% on room air. Chest examination reveals focal crackles in the right lower zone. He has no significant comorbidities, is not pregnant, tolerates oral intake and has not been in hospital or on antibiotics in the last 3 months. You diagnose mild community-acquired pneumonia suitable for outpatient treatment. What is the most appropriate first-line oral antibiotic regimen?