Introduction It is recommended that non-CF bronchiectasis patients have sputum cultured annually. This prospective, cohort study is the first to collect monthly cultures to assess this practise by recording the short term variability of sputum bacteriology.
Method 85 patients with non-CF bronchiectasis and daily sputum production were recruited between December 2010 and May 2011. Patients completed daily symptom diaries, and spirometry and sputum samples were collected monthly for 6 months.
Results 58/85 were female, average age 58 (range 17–82). Most common aetiologies were idiopathic 41/85 and post infective 19/85. 64/85 completed follow up.
There were 417 sputum cultures of which only 265 cultured an organism (incl. 130 Pseudomonas aeruginosa (PA), 37 Staphlococcus aureus, 34 Haemophilus influenzae.) 10/64 patients grew no organism throughout the study despite monthly samples. 30/64 had one or more positive culture for PA, including 6 patients with first isolates. Of those with positive cultures, 28/64 patients grew the same organism in all positive cultures (15/64 grew PA only) whereas 26/64 had variability in the microbe isolated. A total of 37 exacerbations occurred at time of clinic visit. Of these 4/37 were associated with growth of a pathogen not previously isolated in this patient. However, 20/37 sputum samples at the time of clinical exacerbation showed no growth despite no prior antibiotic use. 22 patients used prophylactic antibiotics of whom 14 grew PA and 2 grew no organism.
122 infective exacerbations resulted in the use of 145 antibiotics courses. 14/64 had no exacerbations over 6 months. 9/64 had one and 41/64 had two or more (median 2). Spirometry and symptom scores remained relatively stable throughout the 6 months and were not significantly different in patients with ≥2 exacerbations.
Conclusion This study demonstrates the limitations of annual sputum cultures. There was significant microbe variability and importantly a significant number of first PA isolations over a short follow-up period. Furthermore, a large percentage of patients had no microbe isolated (including at exacerbation) suggesting a possible use of future molecular microbe techniques.