Cystic fibrosis clogs the lungs with thick, sticky mucus

Slightly acidified sodium nitrite, used in the curing of meat, may be able to neutralise a bacterium which weakens the lungs of CF patients.

Pseudomonas aeruginosa thrives in the thick mucus associated with CF and can cause severe complications.

The University of Cincinnati-led study features in the Journal of Clinical Investigation.

We can essentially say that this organism can now be destroyed by nothing more exotic than a common food preservative Dr Daniel Hassett

Cystic fibrosis is a genetic disorder which causes chronic lung damage due to the build-up of excessive amounts of sticky mucus.

A mutated form of P. aeruginosa, which is resistant to conventional antibiotics, exacerbates this process by helping to make the mucus even more sticky and difficult to dislodge.

Immune system foiled

The immune system tries to kill off the bacteria, but cannot reach them because they are so enmeshed in the thick mucus clogging the airways.

This leads to the body's own white blood cells dumping toxins onto the airways, causing destruction of the lungs.

The researchers have discovered that the very mutation that makes the bug such a danger also leaves it vulnerable to attack by sodium nitrite.

Most forms of the bacteria have enzymes that are able to dispose of nitrites - but the key mutated form is deficient.

Tests on 60 samples of the bacteria showed that those carrying the key mutation were all sensitive to the chemical.

Not 'unbeatable'

Lead researcher Dr Daniel Hassett said: "We believe that we have discovered the Achilles' heel of the formidable mucoid form of Pseudomonas aeruginosa, which could lead to improved treatment for cystic fibrosis airway disease.

"We can essentially say that this organism, which some people thought could never be beaten, can now be destroyed by nothing more exotic than a common food preservative."

Dr Hassett said sodium nitrite had potential as a "time-release" capsule for CF patients, because nitrite is degraded very slowly.

He hoped that it could eventually be made available in aerosol form, but conceded that a treatment was still some way off, not least because sodium nitrite potentially has some toxic side effects.

However, nitrites do have current clinical uses, such as to counteract cyanide poisoning, warts and athlete's foot.

Dr Jim Littlewood, chairman of the Cystic Fibrosis Trust, said: "Although it will take a number of years of development to see if this research can help in the treatment of chronic P. aeruginosa infections it is certainly an interesting and potentially important observation.