A 58-year-old woman presents with fever, productive cough and pleuritic chest pain for 3 days. She is otherwise well, with no significant comorbidities. Vital signs: temperature 38.2 °C, respiratory rate 20 breaths/min, blood pressure 122/74 mmHg, oxygen saturation 95% on room air. Chest examination reveals crackles in the right lower zone. Using a validated severity tool, she is classified as low severity. According to Therapeutic Guidelines, what is the preferred empirical oral antibiotic regimen?