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Super Bacteria? Fighting Resistance Could Be Trickier Than Thought

Antibiotic Resistance

First Posted: 07/28/11 07:13 PM ET Updated: 09/27/11 06:12 AM ET

A process thought to hamper antibiotic resistant bacteria, one of the world's most pressing public health problems, might actually make them stronger, according to a new Portuguese study that could signal a dramatic shift in our understanding of bacterial resistance.

Though much is still unknown about the exact mechanics involved, bacteria become resistant to antibiotics via chromosomal mutations and the incorporation of new genes, sometimes from other bacteria.

Researchers had believed that the acquisition of new genes conferring resistance has come at some cost to the bacteria, making it tougher for them to reproduce and survive.

But the authors of the new Portuguese study found that when already resistant bacterial cells obtain another antibiotic-resistance gene from a small piece of DNA called a plasmid -- a development that has been thought to have some cost to the host -- the cells sometimes divide faster than before.

Francisco Dionisio of the University of Lisbon, one of the study's authors, said the results, which focused on the bacterium E. coli, were unexpected.

"It is as if your PC with a mistake or bug in the operating system began to run faster after receiving a computer virus," Dionisio explained in an email to The Huffington Post.

"This happened 52 percent of the cases studied," he added. "And we expected zero percent!"

Other experts echoed Dionisio's surprise.

"It has always been an understanding that the acquisition of these resistant genes comes at some cost, so that the bacteria that have picked up these extra genes have extra baggage, so to speak," said Dr. Arjun Srinivasan, associate director for healthcare associated infection prevention programs at the Centers for Disease Control. "That this might actually make them more fit and able to divide more quickly is a real change."

But the good news for resistant bacteria isn't good news for public health. The findings suggest that curbing antibiotic resistant bacteria -- already a top public health issue, according to the CDC -- may be even more difficult than previously thought. Dr. Jan Patterson, president elect of the Society for Healthcare Epidemiology of America, called the results "concerning." She added that the results could signal a shift in future research and control efforts.

"The finding brings up that just controlling antibiotic use alone is not going to take care of the problems of emergence and persistence of resistance," Patterson said. "We might have to start looking at other ways to fight bacteria, like inhibiting production of plasmids or inhibiting how bacteria divide."

To her knowledge, Patterson said little or no research has been done in that area. In the meantime, she pointed to methods like hand hygiene as a means of limiting the spread of resistant bacteria, particularly in hospitals, where the number of resistant strains is on the rise.

The CDC has identified improving in-patient antibiotic use as priority. It says that 50 percent of antimicrobial use in hospitals is "inappropriate," meaning antibiotics are used when they are not needed or they are administered the wrong dose. Increasing use of antibiotics increases the prevalence of resistant bacteria in hospitals, a recent CDC report stated.

Other broad areas of focus when it comes to preventing antibiotic resistance include limiting the use of antibiotics in farm animals, including pigs and cows.

"The prophylactic and potentially careless use of antibiotics on such a large scale provides perfect breeding ground for drug-resistant strains," said Gunnar Kaufmann, assistant professor of chemical immunology at The Scripps Research Institute.

Such efforts to curb antibiotic use and increase things like hand washing in hospitals will have to suffice for now, the experts agreed, as the public waits for more research on exactly how antibiotic resistance works to be funded so that it has a better chance of being stopped.

"Medicine is a study in humility," Srinivasan of the CDC added. "We learn every day that something we thought was true is not correct. A study like this simply calls upon us to recognize the fact that we don't know everything we need to know yet. We need more investment in these problems."

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