A 55-year-old man presents with fever, productive cough and pleuritic chest pain for 3 days. He is otherwise healthy and manages activities of daily living. Vital signs: temperature 38.5 °C, blood pressure 125/75 mmHg, heart rate 96 bpm, respiratory rate 20 breaths/min, oxygen saturation 96% on room air. Chest examination reveals right basal crackles. CURB-65 score is 0. According to Australian primary care antibiotic guidance, what is the most appropriate empirical oral antibiotic?