Detection of Pseudomonas aeruginosa in exhaled breath of cystic fibrosis patients

Pseudomonas aeruginosa (PA) is one of the most pathogenic bacteria infecting the airways of patients with cystic fibrosis (CF). Sputum culture is the gold standard for detecting PA. However, this method is time-consuming. In this study we hypothesized that volatile organic compounds (VOCs) in exhaled breath can discriminate between PA infected and non-infected CF patients. Design: Cross-sectional baseline analysis of longitudinal cohort study. We collected exhaled air of both pediatric and adult CF patients with and without PA airways infection, in which VOCs were identified using Gas Chromatography – Mass Spectrometry (GC-MS). Infection was defined as culturing PA on the day of breath sampling, or chronic colonization with PA (in >50% of cultures (minimum of 4 samples) over the previous 12 months, or chronic maintenance treatment for PA). To identify VOCs relevant for distinction between the groups, univariate analysis (Mann Withney U test) was applied for each GC-MS compound. Features with a p-value below 0.05 retained for linear discriminant analysis. Diagnostic performed was evaluated by calculation of the area under the receiver operating characteristic - curve including 95% confidence Interval (CI). Complete data was available of 18 pediatric and 22 adult CF patients; 20 with and 20 without PA infection. Exploratory analysis of unselected patients showed that 3 out of 138 VOCs were consistently different in PA infected and non-infected patients, resulting in an AUC of 0.75 (CI 0.59 – 0.92). We discriminated PA infected and non-infected CF patients based on 3 VOCs with moderate accuracy. However, these preliminary results need to be validated in an independent patient cohort.