NR507: Tammy's cough and the escalated differential

The first half wants a differential in explicit order of likelihood, which is a discipline rather than a formality: ordering forces you to say what makes one candidate more probable than another. For Tammy as first described — three weeks of deep productive cough after a resolved coryzal illness, no fever, green sputum, no rhinorrhoea now — acute bronchitis leads, and it is usually post-viral and self-limiting. Pertussis belongs high because the duration, the paroxysms and the post-tussive gagging fit it and the consequence of missing it is transmission. Upper airway cough syndrome from post-nasal drip and cough-variant asthma follow, with gastro-oesophageal reflux and an ACE inhibitor cough further down pending medication history. Treat from the top of that list, which means symptomatic care and explicit reassurance about duration — and say that green sputum is not evidence of bacterial infection, since its colour comes from neutrophil myeloperoxidase.

The escalation is the question that separates answers. Fever, foul-smelling sputum and breath, cups of sputum daily and breathlessness on moderate exertion are four findings that move the picture from an airway irritation to suppurative lung disease. Foul odour specifically suggests anaerobic organisms, which points to lung abscess or aspiration pneumonia; high-volume purulent sputum over time suggests bronchiectasis; and exertional breathlessness indicates that gas exchange or airway calibre is now involved rather than just the cough reflex. Say what the new differential looks like in order, and what you would do about it — chest imaging rather than watchful waiting, sputum culture including anaerobic consideration, and a treatment plan that no longer looks like symptomatic care. Note explicitly that the change in management is what the question is testing: the same patient with four extra findings is someone you now investigate rather than reassure, and saying so is the answer.