A 67-year-old woman presents to her GP with a 3-day history of productive cough, fever 38.3 °C and pleuritic chest pain. Respiratory rate is 22 breaths/min, oxygen saturation 95% on room air, blood pressure 128/76 mmHg and pulse 94 beats/min. Chest auscultation reveals left basal crackles. She has no major comorbidities and is suitable for outpatient management. According to the Therapeutic Guidelines summary for primary care, which empirical antibiotic regimen is most appropriate for her presumed mild community-acquired pneumonia?