''There are patients today in hospitals for whom there are no effective therapies,'' says Gary Doern, director of clinical microbiology at the University of Iowa, a panelist at a briefing here of the International Forum on Antibiotic Resistance.

Until recently, almost all drug-resistant bacteria were confined to hospitals, where a concentration of sick people and high antibiotic use contributed to the evolution of strains capable of evading antibiotic attack.

Now, Doern says, it's not uncommon for patients to come in the door carrying drug-resistant microbes that are circulating in the community. Among concerns highlighted by doctors at the Interscience Conference on Antimicrobial Agents and Chemotherapy:

* Methicillin-resistant Staphylococcus aureus, or MRSA, accounts for more than half of hospital-acquired bloodstream infections caused by staph. In some cities, 31% of such infections outside the hospital are methicillin-resistant, and in nursing homes, 71% of staph infections are MRSA.

* In some areas, about 50% of Campylobacter bacteria, the most common cause of diarrhea, are resistant to Cipro.

* About a third of the germs most commonly responsible for severe pneumonia, Streptococcus pneumoniae, are resistant to penicillin in the USA, and about 25% are resistant to multiple drugs.

* Resistance to fluoroquinolones, a newer class of drugs, also is on the rise. Researchers in Toronto reported Sunday that in 2001, 1.2% of the S. pneumoniae bacteria in Canada were resistant to levofloxacin, a fluoroquinolone introduced in 1996, compared with 0.9% in 2000 and 0.4% in 1999.

''We are living in a time where increasing drug resistance is frustrating treatment of common infections,'' says Roger Finch, professor of infectious diseases at England's University of Nottingham. ''It is having an impact on hospitals and forcing us to use (antibiotics) we might have kept in reserve'' to use only against the most persistent infections.

Antibiotics wipe out bacteria that are susceptible to them. But when used improperly, they can encourage the growth of bacteria that have adapted to them. And because bacteria can swap genes under the right conditions, drug-resistant germs can share their resistance mechanisms with other germs.

That is what is thought to have happened in the case of a Michigan woman reported this summer. She acquired the USA's first case of Staphylococcus aureus, a common bloodstream and skin infection, that was impervious to the antibiotic vancomycin, says Michael Rybak of Wayne State University in Detroit. Vancomycin has been known as the drug of last resort; it is used to treat infections that don't respond to other drugs. But in recent years, it has been used so often that intestinal bacteria called enterococci have become resistant.

The Michigan patient already was infected with vancomycin-resistant enterococci, and those microbes might have passed their drug-resistance mechanisms to the staph bacteria, creating what doctors call a ''superbug.''

As bacteria evolve resistance to more classes of antibiotics, drug companies are racing to create new ones. Rybak presented data Saturday showing that a drug being developed by Cubist Pharmaceuticals, daptomycin, was effective against vancomycin-resistant S. aureus.