December 1, 2011 at 9:08 pm #3106
Study finds how starving bacteria beat antibiotics
By Rick Ruggles
WORLD-HERALD STAFF WRITER
Some bacteria fight off antibiotics even as they starve.
For years, scientists believed antibiotics failed to work against starving bacteria because the medicines’ target spot within the bacteria had slowed or gone dormant.
As it turns out, the bacteria’s starvation triggers a reaction that coincidentally helps them defeat antibiotics, a University of Nebraska Medical Center researcher said.
While this finding doesn’t provide a cure to certain infections caused by these bacteria, it’s a step toward finding one, said Dr. Bradley Britigan, dean of the UNMC College of Medicine. Britigan was one of about a dozen scientists in North America who worked on the project. They published their findings this month in Science magazine.
There’s “still a lot of work ahead,” said Britigan, who came to UNMC in July from the University of Cincinnati, where he participated in the project.
The research studied two kinds of bacteria Pseudomonas aeruginosa and E. coli out of the many that exist. The findings might have broad implications for many bacterial infections, but more work must be done to prove it.
Numerous bacteria tend to band together in a mass called biofilm. Pseudomonas clumped in biofilm sometimes cause infections in the lungs of cystic fibrosis patients, in burn and wound victims, and in eyes containing contact lenses.
Dr. Dao Nguyen, a Canadian physician who is the lead author of the report, said starving E. coli can cause urinary catheter infections and abscesses in the abdomen.
Starving bacteria have the ability to simmer within a person, Nguyen said, and while they don’t make a patient acutely ill, they can cause illness and death over the long haul.
“It is true that they’re not as active as well-fed bacteria, but they’re still capable of tissue damage,” she said. “What happens when they’re starving is their defenses are up.”
Previously, scientists reasoned that the area in the bacteria that the antibiotics targeted had probably shut down because of lack of nutrients.
But this study found that wasn’t why antibiotics failed to work against them. The research, done over several years, found that lack of nutrients or starvation compel the bacteria to release an enzyme that thwarts the oxygen radicals, or toxic molecules, promoted by antibiotics.
The enzyme acts as a starvation alarm, so effectively fighting those bacteria with medicine will require shutting off the alarm system.
Nguyen said it’s possible that other kinds of bacteria, such as those that cause infections in hip and knee replacements, function the same way.
Kenneth Bayles, UNMC’s associate vice chancellor for basic science research, said learning how diseases function is key to defeating them. “When we understand the nuts and bolts of that process, we can find ways to circumvent that process,” said Bayles, who didn’t participate in this study.
Nguyen said research now must find a way to turn off the bacteria’s starvation alarm.
“That would be a great answer to have,” she said. “It’s still too early.”
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