In an age when microbial pathogens are growing increasingly resistant to the conventional antibiotics used to tamp down infection, a team of Wisconsin scientists has synthesized a potent new class of compounds capable of curbing the bacteria that cause staph infections. Writing online on May 6, 2013 in the Journal of the American Chemical Society, a group led by University of Wisconsin-Madison chemistry Professor Helen Blackwell describes agents that effectively interfere with the "quorum sensing" behavior of Staphylococcus aureus (image), a bacterium at the root of a host of human infections ranging from acne to life-threatening conditions such as pneumonia, toxic shock syndrome, and sepsis. "It's a whole new world for us," says Dr. Blackwell, whose group identified peptide-based signaling molecules that effectively outcompete the native molecules the bacterium uses to communicate and activate the genes that cause disease. Bacteria employ quorum sensing to assess their population density and coordinate certain behaviors. They do so through the use of pheromone-like chemicals, which bind to receptors either in the bacterial cell or on its surface and tell it if there are enough companion bacteria around to switch on genes that perform certain functions. In the case of Staphylococcus aureus, quorum sensing activates toxin production, manifesting disease in the host.Interfering with bacterial quorum sensing to stymie disease is considered a promising new antibiotic strategy, says Dr. Blackwell. Staph, she adds, is an excellent target as the bacterium is not only a prevalent pathogen, but some strains, notably methicillin-resistant Staphylococcus aureus or MRSA, have developed resistance to commonly used antibiotics such as penicillin and its derivatives. The new compounds synthesized by Dr.
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