MRSA, or methicillin-resistant Staphylococcus aureus, a bug once found only in hospitals or nursing homes. They are victims of a dangerous newer strain of MRSA that is raging across the country, spreading through communities.
It is causing infections from abscesses to deadly blood poisoning, bone infections and pneumonia, often in the young and the fit, including professional football players, high school athletes and previously healthy children.

Whether it spread from the hospital into the community or developed as a separate strain outside the hospital is a mystery, says John McGowan, professor of epidemiology at Emory University. But recent genome studies suggest the MRSA strain circulating in the community is significantly different from the strains that are typically found in hospitals.

"There are differences in the sequence of the community strain that may make it more virulent, more able to affect people with (healthy immune systems), and with biological differences that make it spread readily," he says.
MRSA has become so common that in many hospitals more than half of all staph infections tested are drug-resistant. That's changing the way doctors treat these common infections.

"When a patient comes in with a staph infection, we assume it's resistant until proven otherwise," says pediatrician Sheldon Kaplan of Texas Children's Hospital in Houston, where MRSA rates have gone from 33% of all staph tested in 2000 to 75%.
Drug-resistant bugs, including MRSA and several others that are emerging in hospitals, are more difficult to treat, requiring stronger antibiotics that are more costly and in some cases have to be given intravenously.

Few new drugs on the way
Few major pharmaceutical companies have new medicines in the pipeline that target the drug-resistant organisms, says George Talbot of the Infectious Diseases Society of America's task force on anti-microbial availability.
"In a number of these companies, there were active decisions taken that antibiotic research was not going to be profitable enough to meet their obligation to shareholders," says Talbot, an infectious-disease specialist and consultant to drug companies. "So they decided to go for drugs that would be taken for a lifetime � drugs for diabetes or high blood pressure � rather than drugs to be taken for a week."

Jumping into the breach are smaller biotech companies that are doing the basic research to identify promising new drugs, he says, "but it's not clear yet that these smaller companies will have the development expertise or financial wherewithal to bring them to market."
In some cases, small companies form partnerships with larger, wealthier drug companies that underwrite the costs of large-scale studies and marketing, he says, "but those deals have to be done in areas where the larger companies perceive an economic benefit."
MRSA, for instance, offers a large market because it is affecting so many people and several antibiotics can be used against it. For lesser-known drug-resistant germs, the treatment options are fewer.

MRSA has been known in hospitals since the 1970s, but in recent years, new strains, which doctors call community-acquired MRSA, have infected people outside health care settings. One of these strains, known as USA300, was identified in 2000 and has been found in at least 21 states.