Don't Talk, Reproduce; May 2009; Scientific American Magazine; by Melinda Wenner; 2 Page(s)

Despite the rising menace of bacteria—at roughly 19,000 a year, more Americans die from drug-resistant Staphylococcus aureus infections than from HIV/AIDS—the microorganisms do deserve some credit for their cleverness. Antibiotic-resistant strains reared their heads 60 years ago, and ever since scientists have been struggling to develop second-generation drugs that attack not the bacteria themselves—which promotes resistance—but rather their cell-to-cell communication with one another. Progress has been slow, however, as bacteria have once again proved more complex than anticipated. But now insights from social evolutionary biology may finally point the way to outsmarting the microbes—by exploiting certain members to undermine the entire group.

Forty years ago scientists discovered that some bacteria send and receive messagesin the form of small moleculesto and from surrounding cells. This kind of communication, called quorum sens-ing, enables bacteria to monitor their population density and to modulate their behavior accordingly. When there are enough cells around to create a quo-rum, bacteria begin producing proteins known as virulence factors that sicken their hosts. They can also grow into aggregates called biofilms that render them up to 1,000 times more resistant to antibiotics.