Variation in cyanide production between different strains of pseudomonas aeruginosa

Aims In cystic fibrosis, Pseudomonas aeruginosa (PA) infection is associated with significant morbidity and mortality. Unfortunately, inpatients who cannot expectorate sputum current diagnostic methods are unreliable, unpleasant or invasive. This has lead to increased interest in using the cyanogenic properties of PA to develop a non-microbiological method for its detection. Prior to this development it needs to be determined if cyanide production varies according to PA strain. Methods The hydrogen cyanide (HCN) released into the gas phase by 96 genotyped PA samples was measured using Selected Ion Flow Tube Mass Spectrometry after 24, 48, 72 and 96 h of incubation. The HCN produced by a range of non-PA cultures and incubated blank agar plates was also measured. Results The 96 samples included 26 different strains; four were previously described epidemic strains (Liverpool, Midlands1, Midlands2 and Stoke). Extremely low levels of HCN ( Discussion This supports previous studies showing PA is one of a limited number of organisms to produce cyanide and SIFT-MS is a sensitive and reproducible way of analysing this. It is the first study to demonstrate that cyanide production is dependent on the PA strain and that the effect of phenotype may vary between strains. As all the PA strains produced more HCN than the controls, it creates further interest in using the cyanogenic properties of PA to develop a diagnostic test.