69 The Cystic Fibrosis Sputum Induction Trial (CF-SpIT). Induced sputum in young healthy non-productive children with cystic fibrosis

Objective Young children with CF are often non-productive of sputum even during a chest exacerbation. Effective bacterial surveillance is challenging, but critical as respiratory infection and lung disease begins early in life. CF-SpIT (CF-Sputum Induction Trial: UKCRN 14615) seeks to identify whether using induced sputum (IS) improves bacterial surveillance, in young non-productive children with CF. Methods 86 children from CF-SpIT are included in this analysis. In all cases, a routine cough swab (CS) was followed by IS. Paired samples were compared for microbiology yield. In 20 children, where bronchoscopy was clinically indicated, CS, IS and extensive 6 lobe bronchoalveolar lavage (BAL) were compared for microbiology yield. Results IS was tolerated in 98% of patients, and successful in 81% (n = 69). Tolerability and success did not differ in children below or above 6 years of age, despite more of the younger cohort being naive to hypertonic saline (30%), not spontaneously productive (92%) and unwell at the time (68%). Of the 69 patients, 17% had positive cough swabs, 47% had positive IS samples (χ 2 = 10. P=0.002). IS identified a pathogen not previously isolated in the previous year in 29% of patients. In 20 patients where CS, IS and BAL were taken, 20 pathogens were grown in 16 patients. CS, IS and BAL identified 5, 13 and 14 pathogens respectively. Pathogens were identified on IS but not on BAL in 4 patients. 16S sequencing of culture-negative BAL was positive for the pathogen identified on IS in 3 of 4 cases. Conclusion Induced Sputum is a well tolerated, non-invasive, effective way to sample the lower airway in young non-productive healthy children with CF.