A 67-year-old man presents with fever, productive cough and pleuritic chest pain. He is otherwise well and lives at home. Vital signs: temperature 38.3 °C, respiratory rate 22 breaths/min, blood pressure 130/78 mmHg, pulse 96 beats/min, oxygen saturation 95% on room air. Chest examination reveals right lower lobe crackles. CURB-65 score is 1. What is the most appropriate initial antibiotic management in the community according to Australian guidelines?