Cystic Fibrosis and Bacterial Communications

Observations of bacteria in CF patients' lungs by a physician (Harvey Rabin) at University of Calgary and conversations with a scientist from the same university (Michael Surette) may have solved this clinical puzzle. Dr. Rabin noticed that CF patients had other bacteria in these mucus plugs that do not cause damage in the lungs. These bacteria are normally found in people's mouths and throats and are called normal flora bacteria. He also observed that when CF patients are having respiratory problems the numbers of Pseudomonas aeruginosa in their lungs are not greater than when the CF patients are having few to no respiratory problems. It didn't seem logical that more damage was being done to the lungs but yet Pseudomonas aeruginosa numbers were not increasing.

After talking with Dr. Rabin, Dr. Surette theorized that maybe the normal flora bacteria in these mucus plugs were in some way causing these respiratory troubles by telling Pseudomonas aeruginosa to make more toxins. Using rather ingenious means Dr. Surette was able to demonstrate that the normal flora in the mucus plugs produce a factor called autoinducer-2 (AI-2) that causes Pseudomonas aeruginosa to produce more toxins without increasing in bacterial cell number. These toxins damage the lungs and cause the respiratory problems. If antibiotics are used they kill the normal flora bacteria, the amount of AI-2 is reduced in the mucus and expression of  Pseudomonas aeruginosa toxin is reduced. Less toxin means less damage and less inflammation resulting in the patient getting better.

The term autoinducer-2 produced by the normal flora is in this case a misnomer. AI-2 is not inducing the bacteria that make it but rather it is inducing Pseudomonas aeruginosa. These findings are really exciting! It is the first demonstration of interspecies communications between bacteria. 

We talk all the time to other species. I frequently talk with my son's dog and he seems to understand most of my comments. I definitely know when the dog is angry or sad. It was thought that bacteria were not complex enough to talk with other bacteria. This study has shown the bacteria do indeed talk with each other and in at least one instance to the detriment of CF patients. Knowing this could however provide scientists with new ways of thinking and could provide new approaches to treating lung infections in CF patients.

For more information go to the following webpages:

An abstract of Dr. Surette's journal article

Information on cystic fibrosis, from the NIH, Cystic Fibrosis Foundation, Cystic Fibrosis.com.

Take Care and Think Microbiologically! For

Go To Page: 1 2 3