A 63-year-old woman with moderate COPD presents with increased cough, sputum volume, and purulent sputum over three days, along with increased dyspnoea. She is afebrile and haemodynamically stable. Oxygen saturation is 92 percent on room air. Chest examination reveals increased wheeze but no focal consolidation. According to Canadian COPD guidance, which of the following best describes when antibiotics are indicated for an acute exacerbation?