P. aureginosa (green line) is the most common cause of infection for CF patients older than 18 years old.By Ninjatacoshell (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)],… — *P. aureginosa* (green line) is the most common cause of infection for CF patients older than 18 years old.
By Ninjatacoshell (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

Cystic fibrosis is a hereditary disease characterized by thick mucus secretions that obstruct the lungs and harbor harmful bacteria in a person’s airways. A common cause of death among CF patients is bacterial infection, usually by Pseudomonas aeruginosa, that subsequently leads to inflammation and respiratory failure. Scientists at the CF Reference Center in Roscoff, France were interested in a possible link between oral bacteria and lung bacteria of CF patients. Specifically, they wondered if the mouth could harbor P. aeruginosa, which could then go on and inflame the lungs. The results of their study were published in the Journal of Clinical Microbiology.

The researchers in France focused their study on detecting and measuring the genetic relatedness of P. aeruginosa in saliva and sputum (mucous) samples in 10 CF patients. Of the 10 patients, 5 were chronically colonized (CC) by P. aeruginosa, with an average age of 23.8 years, and 5 were not colonized (NC), with an average age of 16.6 years. None of the patients had gingivitis or periodontitis.

No P. aeruginosa was detected in oral or sputum samples of NC patients, while 16 samples from the CC patients contained P. aeruginosa. Of the 16 sampled, six were salivary and ten were sputum. From these samples, the researchers discovered that the genetic make-up of the strain samples within each CC patient was more similar to other samples from the same patient than to those of other patients.

Overall, this study suggests that the oral cavity is a possible reservoir of P. aeruginosa and other bacteria that can infect the lungs. While this possibility is suggested by the discovery of similar P. aeruginosa strains in both saliva and sputum, it is not clear if the oral strains can actually descend and infect the lungs. As the article mentions, a longitudinal study that could follow the changes in bacterial colonization in CF patients would be beneficial.