Sputum induction for assessment of lower airway infection in preschool children

Abstract

Background: Sputum samples are used to assess infection and guide management in school-age children with obstructive airway diseases, but collection of non-invasive samples in preschool children is challenging.

Objectives: To determine the safety and feasibility of sputum induction in preschool children and compare infection profile in induced sputum (IS) with cough swabs (CS) and bronchoalveolar lavage (BAL).

Methods: Children ≤6 years with a history of preschool wheeze (PSW), recurrent cough (RC) or cystic fibrosis (CF) managed at a tertiary centre were recruited. CS were taken, then hypertonic saline inhaled and airway clearance performed; sputum was collected by oropharyngeal suction for microbiology and virology. Oxygen saturations and respiratory rate were monitored.

Results: 53 children (22 male) (25 CF; 13 PSW; 15 RC) median age 35 (range 7 – 76) months underwent 60 IS. There were no episodes of desaturation or tachypnoea. Samples were obtained in 57/60 (95%). Bacterial culture was positive in 17/57 (29.8%) IS but only in 4/53 (8%) CS (p=0.003). 6/57 IS samples were positive for Pseudomonas, crucially two of these had a negative BAL. 19/53 children underwent BAL on the day. 42% of BAL samples and 29% of IS had a positive bacterial growth (p=0.5) (Table 1); the associated CS were negative. A virus was detected in 3/17 (17.6%) IS vs. 1/19 (5.3%) BAL (p=0.3).

Conclusions: IS was safe and feasible in preschool children, with significantly more bacterial isolations than CS. Moreover, IS reflected lower airway bacterial and viral infection.