Induced Sputum: A Valuable Tool for Assessing Cellular and Microbiological Characteristics in Cystic Fibrosis Expectorating Teenagers

INTRODUCTION: Cellular characteristics of induced sputum (IS) are not investigated in cystic fibrosis (CF) patients. OBJECTIVES: This pilot study, conducted on 17 expectorating CF adolescents, compared sputa obtained the same day, in a stable period, by autogenic drainage (expectorating sputum, ES) and 4 h later after inhaling hypertonic saline (IS). RESULTS: No difference was noted concerning weight, volume, and percentage of dead cells between the two collection methods. Sample quality (< 50% of dead cells and < 20% squamous cells) was higher in the case of IS than ES (94.1% vs. 58.8%, p = 0.03), with a doubled cell count (p = 0.01), a higher proportion of alveolar macrophages (p = 0.03), and a lower proportion of squamous cells (p = 0.004). The detection of germs increased by 44% in IS samples, possibly modifying therapeutic management in 17.6% of the patients. CONCLUSION: IS improves the quality and the microbiological detection of the sample, even among CF patients who spontaneously expectorate.