MRCP2-4464
A 65-year-old caucasian female presents to the respiratory clinic with a chronic cough that has persisted for 6 months. She was referred by her GP after complaining of the cough, which is productive but without any haemoptysis. The patient’s husband has noticed that she has lost weight unintentionally and has gone down a dress size. Prior to the onset of the cough, the patient was reasonably fit and walked half an hour every day. She has never smoked and has no underlying respiratory pathology. She denies any history of fever or night sweats and recently traveled to Italy for a summer holiday where she visited a famous bird sanctuary.
Upon reviewing her chest radiograph, an increased opacity in the right upper lung field was observed. Further investigations were performed, including a high resolution CT (HRCT) scan, which revealed a cavity in the right upper lobe with associated tree-in-bud appearances in the surrounding lung. There was no associated lymphadenopathy. The following results were obtained: Hb 140g/l, Platelets 400 * 109/l, WBC 11.0 * 109/l, Neuts 6.6 * 109/l, Lymphs 2.0 * 109/l, Eosin 0.01 * 109/l, Na+ 138 mmol/l, K+ 5.0 mmol/l, Urea 3.0 mmol/l, Creatinine 89 µmol/l, CRP 18 mg/l, Sputum MC&S Normal Flora, and Sputum Acid Fast Bacilli (AFB) Positive x 3. Based on this presentation, what is the most likely causative organism?