P238 Superior yield of positive bacterial cultures from sputum induction vs cough swab in children, and its utility in assessing success of pseudomonas aeruginosa eradication therapy

<h3>Introduction</h3> Cystic Fibrosis (CF) patients most commonly suffer from chronic infections of <i>Pseudomonas aeruginosa</i> (PA) which is a very virulent bacteria associated with increased mortality and further hospitalisations. Earlier detection of bacterial cultures can lead to quicker interventions however current sample methods are either too invasive (Bronchoalveolar Lavage) or not sensitive enough (Cough Swabs (CS)). Sputum Induction (SI) uses nebulised Hypertonic Saline (HTS) to instigate a cough reflex within patients that cannot expectorate sputum samples for culture. This project will look into the viability of SI against CS for positive isolations in Paediatric CF patients and particularly focusing on PA therapies directed at eradication (TDE). <h3>Methods</h3> Nebulised HTS used an ultrasonic device in three 5-minute intervals for administration along with spirometry and basic observations. This was a retrospective observational cohort study with cross-sectional elements; data was collected at initial SI event and micro-biological results were catalogued post SI to 01/03/2019. N=244 (SI events) involving 145 patients. Data collated on excel and analysis performed using chi-squared tests. <h3>Results</h3> Median age of 7 years (IQR= 7 years; Q1= 4, Q3=11). The procedure was well-tolerated in 87% of cases with reasons for poor tolerance including: bronchoconstriction (6%), procedural distress (4%), vomiting (1%) and other (2%). There was a 24x fold increase in positive bacterial cultures detected on SI samples only against positive cultures on CS only (94 vs 4) and a 13x fold increase when looking at SI vs CS for PA eradication patients (13 vs 1 respectively). The data presented good evidence that PA TDE was working at an adequate rate, 71.3% patients remained PA free post SI (80.4% of SI events). <h3>Conclusion</h3> HTS is a mucoactive drug that helps reduce the viscoelasticity of mucus and stimulate the mucociliary escalator providing larger and more representative samples. Thus SI can manipulate patients’ management more effectively, which can reduce the mortality of a PA infection. Unfortunately, without Bronchoalveolar Lavage (GOLD standard), the sensitivity of SI cannot be officially confirmed. In conclusion, SI is a superior method over CS for positive bacterial cultures from sputum samples.