Many Americans need look no further than their own noses to find the new bug among us.
Even as area hospitals and doctors report an increase in the number of people showing up with telltale signs of a drug-resistant form of the bacterium Staphylococcus aureus, a new study has found that the strain is finding a cozy home in the nostrils of about 2 million Americans.
The study, published in the Jan. 15 issue of the Journal of Infectious Diseases, is the first look at the prevalence of staph and the methicillin-resistant strain (MRSA). Researchers from the Centers for Disease Control and Prevention examined nasal samples taken from 9,622 people in 2001 and 2002. They found 32% of the samples contained staph bacteria. That translates to nearly 90 million Americans.
Just under 1% of samples had the antibiotic-resistant strain, but that adds up to about 2 million people. Most of those people will never get sick, but people with the bacteria are considered more likely to develop an infection.
And when they touch their noses and shake hands without washing them first, for example, they could be spreading whichever strain of the bug they happen to harbor.
"This is a sort of comprehensive ecology study on staph," says Matthew Kuehnert, epidemiologist with the CDC's National Center for Infectious Diseases. "It's telling us the breadth of isolates that are in people's noses."
Because a study of this magnitude has never been done before, the results on staph and MRSA will act as a baseline for researchers attempting to monitor the potential growth of the strain. Adding to the need to better understand MRSA is that many infected people disclaim contact with any of what were thought to be the riskiest areas outside of hospitals for spread: athletic locker rooms, gyms, prisons and spas.
"I'd say the unexplained cases are now the majority of cases," says Gregory Moran, emergency room physician at Olive View-UCLA Medical Center.
Moran reported last summer in the journal Emerging Infectious Diseases that MRSA is the most common cause of skin infections in patients at his hospital's emergency room. The proportion of MRSA infections increased from 29% in 2001-2002 to 69% in 2003-2004.
Nationwide, MRSA has also become the most common cause of skin infections seen in emergency rooms. A new study under review by the New England Journal of Medicine, he said, looked at 11 centers nationwide and found MRSA to be the cause in 59% of skin infections.
"Once it's out in the community, it becomes really hard to nail down exact risk factors," Kuehnert says. "There's so much opportunity for exposure."
And MRSA is clearly at home in the community.
Once, hospitals, nursing homes, dialysis centers and other health care facilities settings were places of highest risk for infection with Staphylococcus aureus. Now the new strain of infection is widespread enough to be making its way back inside healthcare settings.
A staph infection typically shows up on skin as a pimple, rash or boil that can spread painfully. It's often initially pooh-poohed as a spider bite.
The bacterium can be transmitted quickly in overcrowded conditions such as jails. One outbreak in Alaska occurred among natives using a sweat lodge. The usual prevention efforts call for diligent hand-washing, keeping wounds clean and covered and not sharing items such as razors.
And at the gym, put a clean towel between yourself and any sports club equipment. "Men, keep your T-shirt on when lying on the bench press," says Elizabeth Bancroft, medical epidemiologist with the L.A. County Department of Health Services.
Often, staph can be successfully treated simply by lancing and draining the boil and treating the wound. If antibiotics are needed, some drugs are still capable of successfully knocking out either strain. But Bancroft cautions that if a physician prescribes an antibiotic, the full course of treatment must be completed. Uncompleted courses of treatment don't wipe out the infection and can strengthen the bacteria, allowing it to develop resistance to another antibiotic.
Untreated, staph can enter the blood stream or bones and can be fatal.