the world's most dangerous diseases

New York -

Athletes with infected scrapes that won't go away. Hundreds of soldiers returning from Iraq with wound infections that don't respond to most antibiotics. Often deadly pneumonias. Ninety-thousand patients who die in hospitals every year. That's the toll in the U.S. from germs that are resistant to existing medicines.

The problem is that many common bacteria and fungi have evolved into being resistant to the drugs that have kept them at bay for a half-century. The problem is not new (see: " Bug Wars"), but it is still getting worse, even as a spattering of new antibiotics and anti-fungal drugs reach the market. Now, doctors are trying to get more attention for the problem, hoping that comprehensive legislation could stimulate drug firms to put more effort into developing new antibiotics.

Today, the Infectious Diseases Society of America, an association of 8,000 infectious-disease specialists, is announcing a hit list of the six most worrisome germs doctors now face in clinical practice. The list, which includes five bacteria and one fungus, is described in the current issue of Clinical Infectious Diseases, a medical journal, and will also be unveiled as part of a press conference today. For all of these germs, the authors see very few new drugs being developed and rising rates of illness.

In Pictures: The Six Scariest Germs

In some cases, the problem is particularly gruesome. To treat soldiers returning from Iraq with wound infections caused by Acinetobacter baumannii, doctors are resorting to using a drug called colistin. The medicine fell out of use decades ago because it can cause severe damage to the kidneys (see: " The Iraq Infection"). The authors of the IDSA report note that Acinetobacter can also cause pneumonia; mortality rates for the pneumonia can be 20% or more.

Why are there so few new medicines targeted at resistant bacteria? In the past decade, many big pharmaceutical players, including Wyeth (nyse: WYE - news - people ), Roche and Eli Lilly (nyse: LLY - news - people ), backed off antibiotic research. At the same time, new antibiotics were becoming increasingly difficult to develop. For 30 years--until 2000--there were no new classes of antibiotics approved.

In the past six years, there have been two clear examples: Zyvox, from Pfizer (nyse: PFE - news - people ), and Cubicin, from Cubist Pharmaceuticals (nasdaq: CBST - news - people ). Wyeth's Tygacil and Sanofi-Aventis' (nyse: SNY - news - people ) Ketek have been touted as new classes, and though the distinction can be argued, both were definitely better at fighting resistant bugs.

Drug companies are starting to become interested in antibiotics again. Pfizer, which always kept a presence in developing new germ-killing drugs, saw its Zyvox become a fast-growing drug in recent years. Then it bought antibiotics maker Vicuron last summer; an antifungal medicine from the deal was approved on Feb. 21. Abbott Laboratories' (nyse: ABT - news - people ) Omnicef, an antibiotic pill, saw sales increase 61% to $627 million last year, according to consulting firm IMS Health (nyse: RX - news - people ).

Biotechs are benefiting too. Shares in antibiotic maker Cubist Pharmaceuticals have more than doubled this year based on sales of Cubicin, its injectable treatment for Staphylococcus aureus, one of the bugs topping the IDSA's hit list (see: " A Better Antibiotic?").

But the IDSA authors say the antibiotics in development simply aren't enough. A review of new medicines finds few that work in new ways, meaning that some of the new drugs may hit the market already facing some resistant bugs. And the authors say the drug companies are not developing drugs to treat the organisms that are the biggest health threat. Market forces, they worry, may not take care of the problem.