It all began with what looked like a spider bite on Eileen Moore's left thigh. Nothing to worry about, she figured.
Within 24 hours, the "bite" became a 6-inch welt with a bubble of pus that eventually ripened into a black wound. Over the next few months, scabs dotted her face. A hangnail caused her middle finger to bloat like a sausage. Her pierced ears oozed pus.
The cause of Moore's ordeal was a bacterium known as methicillin-resistant Staphylococcus aureus, which in its most severe form can turn into a fatal flesh-destroying scourge.
For decades, the infections were found only in hospitals, where the constant use of different antibiotics, including the potent methicillin, made it resistant to many of the most powerful antibiotics.
In the last few years, it has emerged in gyms, jails, schools -- and just about anywhere bacteria can grow. It has become a simmering problem that is largely unknown by the general population.
"I would characterize it as widespread, and in some areas it is epidemic," said Jeff Hageman, an epidemiologist at the Centers for Disease Control and Prevention and a coauthor of two studies on staph published last year.
There are few statistics on the disease, because resistant staph infections are not routinely reported to the CDC. But one study published last year in the journal Emerging Infectious Diseases estimated there were about 126,000 cases from 1999 to 2000 -- twice the number of hepatitis B cases each year.
"The rapidity with which this has emerged over the last two to three years is probably unprecedented," said Donald Low, a microbiologist at the University of Toronto who was one of the key scientists who dealt with Toronto's SARS outbreak in 2003. "When you look at the numbers, this way outstrips other so-called new infectious diseases."
Its victims are legion.
Five football players with the St. Louis Rams developed lesions on their elbows, forearms or knees, where turf burns had opened up their skin in 2003. Players from a competing team also developed sores after playing against the Rams.
San Francisco has seen a surge of this antibiotic-resistant bacteria in intravenous drug users and homeless people.
In 2004, actress Hilary Swank found a blister on her foot while training at a Brooklyn boxing gym for her part in the film "Million Dollar Baby." It turned out to be a staph infection.
Moore, a 38-year-old La Canada Flintridge software consultant, has no idea where she got her infection. All she knows is that it took four debilitating months with three increasingly powerful antibiotics to rid herself of the disease.
These days, she views every rash and pimple with suspicion.
"I'm a germophobe now," she said.
A large part of the problem in combating the staph bacterium is that it is ubiquitous.
More than 30% of Americans carry some kind of staph infection in their nose. About 1% have the methicillin-resistant strain, and half of those have an even newer strain that is less resistant, but more damaging. Many carriers never develop a skin infection, either because they have some unknown immunity or because the bacteria never have an opportunity to penetrate their skin through a wound or rash. But carriers can still spread the disease.
Staphylococcus aureus was first identified in the 1880s. It was named aureus, or golden in Latin, because of its distinctive color.
It survived as a relatively undistinguished microbe until the mid-20th century. The introduction of the first antibiotic, penicillin, in 1941 set the bacterium on its deadly journey of mutation. It took just two years for reports to trickle in of the bacterium's resistance.
In the early 1960s, doctors deployed a new antibiotic, methicillin, against the disease. The first signs of resistance appeared in less than a year.
The resistant strain became ingrained in hospitals in Europe, Australia and the U.S.
By the early 1990s, methicillin-resistant staph infections became the leading cause of hospital-acquired skin infections in the U.S. Recent studies have shown that this kind of staph bacterium has also colonized hospitals in Egypt, Taiwan and South America.
It was inevitable that the resistant bacterium would emerge elsewhere.
The first smattering of cases of what came to be known as community-acquired methicillin-resistant Staphylococcus aureus appeared as early as 1990.
The community strain is genetically different from that found in hospitals. Because it has not been bombarded by as many antibiotics, it is less resistant to drugs, but is more virulent.
To gauge the prevalence of the strain, researchers at Olive View-UCLA Medical Center in Sylmar analyzed skin infections that showed up in their emergency room. In 2002, methicillin-resistant staph caused 29% of those infections. Two years later, the rate was 64%.
A study published last year in the New England Journal of Medicine estimated there were about 26 community-acquired cases per 100,000 people in Atlanta and 18 per 100,000 people in Baltimore.