TUESDAY, Nov. 16 (HealthDay News) -- Researchers have found that many cystic fibrosis (CF) patients in Canada have a common transmissible strain of the bacteria Pseudomonas aeruginosa, which can increase the risk of death or the need for a lung transplant.

It's not known if the strain, first identified in the U.K., is yet common among CF patients in the United States.

Researchers looked at 446 CF patients in Ontario and found that 102 of them were infected with one of two common strains. Sixty-seven were infected with strain A, 32 were infected with strain B, and three were infected with both strains.

The study appears in the Nov. 17 issue of the Journal of the American Medical Association.

According to background information in the study, the significant variation in the prognosis of patients with P aeruginosa may partly result from differences among infecting strains.

Strain A was genetically identical to the Liverpool (England) epidemic strain first identified in 1996, but strain B has not previously been regarded as an epidemic strain. The three-year risk of death or need for a lung transplant was twice as high in patients with strain A (18.6 percent) than in those with unique strains (8.7 percent). The risk for patients with strain B was similar to those with unique strains.

"The results of our study indicate that a sizable minority of adult Canadian patients with CF living in the province of Ontario are infected with 1 of 2 common strains of P aeruginosa. The most prevalent transmissible strain found was the Liverpool epidemic strain, which was found to infect more than 15 percent of Ontario patients. This same strain is known to infect approximately 11 percent of patients with CF who receive their care in 1 of 15 CF clinics in England and Wales," wrote Dr. Shawn D. Aaron of Ottawa Hospital Research Institute and colleagues in a news release from the journal publisher.

"Our study is the first report to suggest that common strains of P aeruginosa are shared among patients located on different continents," they added. "Our data suggest that cross-infection with P aeruginosa has occurred widely both within Ontario and between CF centers in the United Kingdom and Canada."

More information

The U.S. National Heart, Lung, and Blood Institute has more about cystic fibrosis.