The sensitivity and specificity of pseudomonas aeruginosa detection using hydrogen cyanide concentration in exhaled breath - The SPACE study

Gilchrist, Francis; Jones, Andrew; Webb, Kevin; Smith, David; Lenney, Warren

Abstract

Introduction

Hydrogen cyanide (HCN) is an in-vitro marker of Pseudomonas aeruginosa (PA). This is the first in-vivo study to investigate if HCN is an early marker of PA infection in children with cystic fibrosis (CF).

Methods

Children who had not grown PA in the last year were recruited from 8 CF centres. At each CF appointment for the next 2 years they provided an exhaled breath sample and completed a questionnaire about symptoms and antibiotic use. The HCN concentration of the breath sample was analysed using selected ion flow tube mass spectrometry. At study completion the results of the routine microbiology samples were compared to the HCN concentrations.

Results

233 children were recruited, median (IQR) age: 8 (5.0-12.2) years. The median duration of follow-up was 2.0 (1.7-2.3) years with a total of 2086 clinic visits and 2072 breath samples. The median number of breath samples per child was 9 (6-12). There were 71 new PA isolates with an incidence of 0.19 cases per patient year. A study visit (with proforma and breath sample) had been completed within 7 days (+/-) of the culture result for 57 of the new PA isolates. 24/57 (42%) children were asymptomatic at the time of the PA isolate. An elevated HCN concentration (>5ppb) was present in 28/57 breath samples (sensitivity 49%). In 5 children the elevated HCN concentration preceded the PA culture by > 2 months. 8 children who did not isolate PA had an elevated HCN at some point (specificity 95%).

Conclusions

In children with CF, an elevated HCN concentration in exhaled breath is a specific marker of PA infection. Further studies are required to investigate if the sensitivity can be improved.

Citation

Gilchrist, F., Jones, A., Webb, K., Smith, D., & Lenney, W. (2014, September). The sensitivity and specificity of pseudomonas aeruginosa detection using hydrogen cyanide concentration in exhaled breath - The SPACE study. Presented at ERS 22nd Annual Congress 2014, Munich, Germany

• Presentation Conference Type: Speech
• Conference Name: ERS 22nd Annual Congress 2014
• Conference Location: Munich, Germany
• Start Date: Sep 6, 2014
• End Date: Sep 10, 2014
• Deposit Date: Jan 12, 2024
• Publisher URL: https://erj.ersjournals.com/content/44/Suppl_58/3444