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Friday, April 29, 2011

Antibiotic-resistant bacteria have evolved a unique chemical mechanism, new discovery reveals

An article from E! Science News :

" For the first time, scientists have been able to paint a detailed chemical picture of how a particular strain of bacteria has evolved to become resistant to antibiotics. The research is a key step toward designing compounds to prevent infections by recently evolved, drug-resistant "superbugs" that often are found in hospitals, as well as in the general population.

A paper describing the research, by a team led by Squire Booker, an associate professor in the department of chemistry and the department of biochemistry and molecular biology at Penn State University, will be posted by the journal Science on its early-online Science Express site on 28 April.

This paper is a continuation of research led by Booker published in another paper in Science earlier this month. The team began by studying a protein made by a recently evolved "superbug." Booker explained that, several years ago, genetic studies had revealed that Staphylococcus sciuri -- a non-human bacterial pathogen -- had evolved a new gene called cfr. The protein created by this gene had been found to play a key role in one of the bacterium's mechanisms of antibiotic resistance. Later, the same gene was found to have crossed over into a strain of Staphylococcus aureus -- a very common kind of bacteria that constitutes part of the flora living in the human nose and on the skin, and which is now the cause of various antibiotic-resistant infections

Because this gene often is found within a mobile DNA element, it can move easily from a non-human pathogen to other species of bacteria that infect humans. "The gene, which has been found in Staphylococcus aureus isolates in the United States, Mexico, Brazil, Spain, Italy, and Ireland, effectively renders the bacteria resistant to seven classes of antibiotics," Booker explained. "Clearly, bacteria with this gene have a distinct evolutionary advantage. However, until now, the detailed process by which the protein encoded by that gene affected the genetic makeup of the bacteria was unclear; that is, we didn't have a clear 3D picture of what was going on at the molecular level."

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