Measuring the health status of cystic fibrosis (CF) patients would now get easier as researchers have found that exacerbations in CF are linked to chronic infection with a bacterium called Stenotrophomonas maltophilia.
The finding that chronic infection with S. maltophilia is independently linked with an increased risk of exacerbations gives clinicians and researchers a new potential target in fighting their disease as well.
"Our study showed that chronic infection with S. maltophilia, which was previously not regarded as prognostically significant, may have a real impact on the progression of CF in patients," said Valerie Waters of the Hospital for Sick Children in Toronto.
To assess whether S. maltophilia represented a true infection, rather than merely a colonizing organism, and whether it had an impact on the progression of disease, Waters and colleagues performed a two-stage study.
In the first stage, they sought to determine if S. maltophilia generated an immune response in CF patients.
In the second stage, they retrospectively followed almost 700 CF patients for 12 years to determine whether chronic infection with S. maltophilia was independently associated with an increased risk of exacerbation or lowered lung function.
They found that antibody levels to S. maltophilia flagellin, were about two times higher in chronically infected patients compared to those who were never infected, indicating a specific immune response and a true infection, rather than mere colonization.
The increased antibody levels were also associated with lower lung function, as measured by FEV1 (forced expiratory volume in one second.)
Furthermore, they found that patients with chronic S. maltophilia infections had a 63 percent greater risk of exacerbations than those who had never been infected, although there were no significant differences detected in the rate of lung function decline.
"It is crucial that we look to determine whether chronic S. maltophilia infection directly results in the worsening of lung function.
"We plan to investigate the effects of chronic S. maltophilia during pulmonary exacerbations in future studies," said Waters.
The findings were published online in the American Journal of Respiratory and Critical Care Medicine.