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TUESDAY, Dec. 17, 2013 (HealthDay News) -- A single strain of antibiotic-resistant E. coli bacteria has become the main cause of bacterial infections in women and the elderly worldwide over the past decade and poses a serious health threat, researchers report.
Along with becoming more resistant to antibiotics, the "H30-Rx" strain developed the unprecedented ability to spread from the urinary tract to the bloodstream and cause an extremely dangerous infection called sepsis.
This means that the H30-Rx strain poses a threat to the more than 10 million Americans who develop a urinary tract infection each year, according to the study authors.
One expert said the finding is disturbing, but could also offer researchers some hope.
"With the wide spread presence of antibiotic resistance in E. coli, it is making infections more difficult to treat and is leading to increased mortality," said Dr. David Samadi, chairman of urology, Chief of Robotic Surgery at Lenox Hill Hospital in New York City.
But, he added that "H30-Rx may provide opportunities for vaccine or prevention strategies, which could play a huge part as E. coli [strains] become resistant to our best antibiotics."
Researchers led by Lance Price, of the George Washington University School of Public Health and Health Services, in Washington, D.C., said this strain appears to be much more able than other E. coli strains to move from the bladder to the kidneys and then into the bloodstream.
H30-Rx may be responsible for 1.5 million urinary tract infections and tens of thousands of deaths each year in the United States, according to the study published Dec. 17 in the journal MBio.
Genetic analyses revealed how H30-Rx came into being. More than two decades ago, a strain called H30 developed mutations in two genes. This resulted in a clone called H30-R, which was resistant to the antibiotic Cipro. Soon after, H30-R gave rise to H30-Rx, which is resistant to several antibiotics.
By focusing on H30-Rx, it might be possible to develop a vaccine that could prevent many infections, according to the study authors.
"This strain of E. coli spreads from person to person, and seems to be particularly virulent," study co-author James Johnson, of the Veterans Affairs Medical Center and the University of Minnesota, said in a journal news release.
"This study might help us develop better tools to identify, stop or prevent its spread by finding better ways to block the transmission of the superbug, or by finding a diagnostic test that would help doctors identify such an infection early on -- before it might have the chance to turn lethal," he explained.
"We now know that we are dealing with a single enemy, and that by focusing on this strain we can have a substantial impact on this worldwide epidemic," study co-author Evgeni Sokurenko, of the University of Washington School of Medicine, said in the news release.
The U.S. National Institute of Allergy and Infectious Diseases has more about E. coli.