Researchers at University of California - Irvine ( UCI ) have found that breath-analysis testing may prove to be an effective, non-invasive method for detecting the damaging lung-bacteria growth seen in cystic fibrosis, which would allow for early stage treatments that can extend the health of people with this disease.

By using a chemical analysis method developed for air-pollution testing, UCI chemists and pediatricians have found that people with cystic fibrosis exhale higher concentrations of sulfur compounds from their lungs than do people who don't have the disease.

These sulfur compounds, called sulfides, are known to be produced by bacteria, and lung disease in cystic fibrosis is accompanied by bacterial infections that cause chronic damage.
The researchers found that the worse the pulmonary function in the cystic fibrosis patient, the higher the sulfide concentration in the breath sample, suggesting an increased amount of bacterial growth in the lungs.

" Early detection and antibiotic therapy has been promoted as a means to delay chronic bacterial lung growth and prolong life, and breath analysis may be an effective first step toward treatment," said Dan Cooper, at UCI Medical Center, who led the study with F. Sherwood Rowland, and Donald Blake. " In the long term, these findings on sulfide levels also might help uncover some of the underlying mechanisms of the disease."

Study results appear in the Proceedings of the National Academy of Sciences ( PNAS ).

Cystic fibrosis is a genetic disease marked by an abnormally thick, sticky mucus that clogs the lungs and leads to life-threatening lung infections.
Although many lung bacteria are prevalent with the disease, in teens and adults, the Pseudomonas aeruginosa bacteria appears as the most prevalent cystic fibrosis pathogen and is strongly associated with respiratory deterioration and mortality.
Over time, the bacteria transforms into treatment-resistant variants, and early detection is seen as key for aggressive antibiotic treatments to delay its growth.

In the study, Michael Kambourse, working with Blake and Rowland, examined exhaled breath from people with and without cystic fibrosis using laboratory methods developed for their atmospheric chemistry work.

In analyzing the breath samples, the researchers monitored levels of three sulfides in the cystic fibrosis patients -- carbonyl sulfide, dimethylsulfide and carbon disulfide.

Significantly, they found that cystic fibrosis patients exhaled carbonyl sulfide ( OCS ) at rates up to 2½ times higher than people who don't have the disease, making it an attractive target for future breath analysis.

The study determined that the regular air the test subjects breathed in had about 600 parts-per-trillion volume ( pptv ) of OCS.
The non-cystic fibrosis subjects exhaled a mean average of 350 pptv of OCS, meaning that about 250 pptv of OCS was removed from the inhaled air.
The cystic fibrosis subjects exhaled a mean average 490 pptv of OCS, and the three individuals with the weakest pulmonary function exhaled as much as 800 pptv, producing an excess of OCS.
This suggests a substantial OCS source, probably bacterial, exists in their lungs, in addition to poorer processing of inhaled gas.

Source: University of California – Irvine, 2005


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