What doesn't kill you makes you stronger, the old saying goes. And infectious diseases are getting stronger -- which means that existing drugs no longer are curing them.

Infectious diseases are mounting a worldwide comeback as they evolve to become more and more resistant to drugs used to treat them. Infectious diseases each year cost $30 billion to treat and cause 100,000 deaths in the United States alone.

In short, the increasing drug resistance of such disease-causing bacteria no longer can be ignored without incurring even greater risks of widespread outbreaks. But there still is time to reverse the trend, says Barry Rosen, chairman of the department of biochemistry and molecular biology at the School of Medicine.

"It's not a crisis right at this moment, but we can't afford to ignore it," Rosen says. The need to act immediately, he says, stems from the fact that lead time for the development of new drugs is at least a decade and diseases thought to have been eradicated are showing up in ever stronger forms.

About 100 years ago, one person in seven died of tuberculosis, says Shahriar Mobashery, associate professor of chemistry. Through the development of new drugs, the disease was all but eradicated.

"But now there is a new strain of tuberculosis that is resistant to nearly every antibiotic we have," Rosen says. "This is an especially dangerous situation for HIV-infected patients."

Mobashery adds, "We're running out of effective drugs, and without new drugs we're going to be back where we were 100 years ago."

To spark discussion on the topic, Rosen and Mobashery organized a symposium to be held Thursday, May 29, in the School of Medicine (see related story).

"Resolving the Antibiotic Paradox: Progress in Drug Design and Resistance" will feature nationally known experts Stuart Levy, author of The Antibiotic Paradox; and Michael Gottesman, deputy director of intramural research of the National Institutes of Health and a leading authority in cancer chemotherapy.

"The problem is more widespread than just resistance in infectious diseases," Rosen says in explaining the symposium's inclusion of cancer experts. "It affects our ability to treat cancer as well. We have very effective chemotherapies for the treatment of cancer. They are very initially quite successful but frequently fail in the long run because cancer cells, like bacteria, develop resistance to the chemotherapeutic drugs."

The situation is not without hope, Rosen says, as companies that developed or modified drugs in the 1960s and 1970s and gotten out of that practice are now getting back in.

And none too soon, he is quick to add. "If we don't get busy right now, we're not going to have new drugs. The organisms will catch up with us."