Antibiotics can prolong the lives of individuals with cystic fibrosis, but the drugs also allow treatment-resistant bacteria to thrive in the lungs, a recent, small study suggests.
Cystic fibrosis is a chronic disease in which the body produces thick, sticky mucus that clogs the lungs. The accumulation of the mucus leaves people prone to serious, hard-to-treat and recurrent infections. Eventually, the repeated infections destroy the lungs.
The findings from the 10-year investigation suggest, but do not prove conclusively, that the current standard of aggressive antibiotic treatment for cystic fibrosis patients may not always be the best approach.
Aggressive use of antibiotics actually lowers the diversity of lung bacteria, resulting in infections that are increasingly difficult to treat. A more diverse community of lung bacteria may help keep the most dangerous strains in check, the researchers noted.
In the study, researchers examined bacteria from six patients collected over eight to nine years. Half of the patients had a relatively stable type of cystic fibrosis and the others had the more typical, faster-progressing form. The investigators conducted DNA analysis on bacteria in 126 sputum samples.
Over time, the researchers found that bacterial diversity declined, yet the overall level of bacteria remained fairly constant. The study authors explained that this means a small number of organisms multiply to take the place of those that have been killed off by antibiotics.
"The conventional wisdom has been that as patients with cystic fibrosis age and become sicker, their lung disease progresses and more bacteria move in," John LiPuma, MD, research professor of pediatrics and communicable diseases at the University of Michigan Medical School in Ann Arbor, said. "But our studywhich was the first to examine the bacterial communities in cystic fibrosis patients' lungs over a long period of time-indicates that's not what happens.
"What we normally do is essentially carpet bombing with antibiotics," Dr. LiPuma explained. "However, what we found is that over time this ultimately assists treatment-resistant bacteria by getting rid of their competition."
He said the findings may be a first step toward developing new treatment methods, such as more focused use of antibiotics or even distribution of beneficial bacteria to cystic fibrosis patients.
The study was published in the Proceedings of the National Academy of Sciences.