A 30-year-old previously well man presents with a 3-day history of fever, productive cough and pleuritic chest pain. Respiratory rate is 20 breaths per minute, blood pressure 118/72 mmHg, pulse 96 beats per minute and oxygen saturation 96% on room air. Chest examination reveals right lower zone crackles. He has no comorbidities, no recent travel and is managed as an outpatient. According to Therapeutic Guidelines, what is the recommended first-line empirical antibiotic regimen?