RT Journal Article SR Electronic T1 Exhaled breath hydrogen cyanide as a marker of early Pseudomonas aeruginosa infection in children with cystic fibrosis JF ERJ Open Research JO erjor FD European Respiratory Society SP 00044-2015 DO 10.1183/23120541.00044-2015 VO 1 IS 2 A1 Francis J. Gilchrist A1 John Belcher A1 Andrew M. Jones A1 David Smith A1 Alan R. Smyth A1 Kevin W. Southern A1 Patrik Španěl A1 A. Kevin Webb A1 Warren Lenney YR 2015 UL http://openres.ersjournals.com/content/1/2/00044-2015.abstract AB Hydrogen cyanide is readily detected in the headspace above Pseudomonas aeruginosa cultures and in the breath of cystic fibrosis (CF) patients with chronic (P. aeruginosa) infection. We investigated if exhaled breath HCN is an early marker of P. aeruginosa infection.233 children with CF who were free from P. aeruginosa infection were followed for 2 years. Their median (interquartile range) age was 8.0 (5.0–12.2) years. At each study visit, an exhaled breath sample was collected for hydrogen cyanide analysis. In total, 2055 breath samples were analysed. At the end of the study, the hydrogen cyanide concentrations were compared to the results of routine microbiology surveillance.P. aeruginosa was isolated from 71 children during the study with an incidence (95% CI) of 0.19 (0.15–0.23) cases per patient-year. Using a random-effects logistic model, the estimated odds ratio (95% CI) was 3.1 (2.6–3.6), which showed that for a 1- ppbv increase in exhaled breath hydrogen cyanide, we expected a 212% increase in the odds of P. aeruginosa infection. The sensitivity and specificity were estimated at 33% and 99%, respectively.Exhaled breath hydrogen cyanide is a specific biomarker of new P. aeruginosa infection in children with CF. Its low sensitivity means that at present, hydrogen cyanide cannot be used as a screening test for this infection.Exhaled hydrogen cyanide is a specific but insensitive biomarker of new P. aeruginosa infection in children with CF http://ow.ly/TdRaF