Bacteria evolve 'dome' to hide, resist

Researchers say biofilm is in most health infections
Dr. Jose A. Vazquez (left) and Dr. Stuart A. Thompson study bacteria in the lab at Georgia Regents University.Thompson got a grant to study the bacteria that make 2 million people sick every year.



Bacteria are increasingly using a “dome” to evade the immune system, develop resistance in the body and thrive in the environment, researchers at Georgia Regents University said.

Dr. Stuart Thompson recently received a $1.5 million grant to study a key regulatory protein in the Campylobacter jejuni bacteria, which sickens about 2 million people a year in the U.S. Poultry can have millions of the bacteria living in them without getting sick, but it takes only about 500 to make a human sick, so cleaning it after processing becomes an enormous challenge, Thompson said.

“They can do a 99.999 percent job, but there is still enough on a piece of chicken to make you sick if you don’t cook it properly,” he said.

Poultry isn’t the only source, however; a study in the United Kingdom found that half of the Campylobacter bacteria found in patients actually came from the environment, such as surface water. That could help explain why the bacterial infections spike in the summer, Thompson said.

“Everybody is out swimming and out in the environment a lot more, and potentially with the temperature maybe the burden of bacteria in the environment is higher as well,” he said. The bacteria also is highly sensitive to oxygen, raising the question of how it survives in the environment and on packages of meat.

“We think one of the reasons is biofilms,” Thompson said.

Biofilms are a matrix of cells the bacteria form that creates a kind of dome they can hide under, said Dr. Jose Vazquez, the chief of the section of infectious disease at GRU. It shields the bacteria not only from oxygen but also from extremes in temperature, he said.

“It maintains its own environment within this biofilm,” said Vazquez, who studies it in another prevalent bacteria, methicillin-resistant Staphylococcus aureus. When it is formed in the body, it also helps the bacteria elude the body’s defenses, Vazquez said.

“It acts as a Trojan horse within the body,” he said. “In other words, the body does not recognize the bacteria as an enemy. So there is no immune response, there is no inflammatory response.”

Biofilms are so prevalent in infections that the National Institutes of Health said they are involved in most of the 2 million health care-acquired infections that kill about 100,000 people a year.

“It’s everywhere,” Vazquez said. “Middle ear infection in your kids? Biofilm. Pneumonia is a biofilm. Urinary tract infection is a biofilm.”

The bacteria is also speeding up antibiotic resistance. Bacteria, even bacteria of different types, can congregate under a biofilm and exchange genetic material, particularly those traits that help confer resistance to powerful antibiotics, Thompson said.

“They make each other better,” he said.

The condition has gotten to the point for Vazquez that he has had some patients for whom no antibiotic works and the patient dies.

“It doesn’t happen often, but it is happening more often than it used to in the past,” he said.


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