A 69-year-old man with COPD (FEV1 45 percent predicted) presents with increased dyspnoea and increased sputum volume and purulence for 3 days. He is afebrile and haemodynamically stable. There is no consolidation on chest X-ray. According to current primary care antibiotic guidance, which is the most appropriate oral antibiotic regimen if you decide antibiotics are indicated?