Standard Drug-Testing Method Contains Flaws.

• Position: ANTIBIOTICS

When a patient is prescribed the wrong antibiotic to treat a bacterial infection, it is not necessarily the physician who is at fault. The current antibiotic assay--standardized in 1961 by the World Health Organization--is potentially flawed; so says University of California, Santa Barbara, biologist Michael Mahan, whose lab has developed a new antimicrobial susceptibility test that could transform the way antibiotics are developed, tested, and prescribed.

The standard test specifies how well drugs kill bacteria on petri plates containing Mueller-Hinton Broth, a nutrient-rich laboratory medium that fails to reproduce most aspects of a natural infection. Now, Mahan and colleagues have used a model to demonstrate that a variety of antibiotics work differently against various pathogens when inside the mammalian body.

"The message is simple: physicians may be relying on the wrong test for identifying antibiotics to treat infections," says Mahan, professor in the Department of Molecular, Cellular, and Developmental Biology. "By developing a test that mimics conditions in the body, we have identified antibiotics that effectively treat infections caused by diverse...