How MRSA Works

CPhoto courtesy Rocky Mountain Laboratories/

As if you didn't have enough to worry about, now there's the superbug to contend with. No, it's not a giant mantis bent on world conquest. The superbug is a bacterium with a familiar name -- staph. And although this tiny invader doesn't possess 8-foot-long pincers like a giant mantis, it's just as deadly. What's worse, although we could probably take down a giant mantis with bullets -- or possibly rockets -- the superbug becomes harder to kill with each passing day.

It's also getting easier for the bug to kill us. In 2005, 19,000 people died from MRSA infections in the United States, and an average of 6.3 out of every 100,000 infections resulted in death [source: JAMA]. That's more than the number of people who died of AIDS complications in the same year. In the United Kingdom, cases of MRSA increased from 210 cases in 1993 to 5,300 in 2002 [source: University of Warwick].


Methicillin-resistant Staphylococcus aureus, or MRSA (the superbug), was first noticed by physicians in the 1970s. The medical establishment kept an eye on the bug but found it could be killed by a round or two of traditional antibiotics. However, things have changed. Because of improperly taken prescriptions, as well as the presence of antibiotics in our food and water, this staph bug mutated and evolved into the superbug. Due to survival of the fittest, those strains that had lived through an assault of antibiotics went on to breed replicas of themselves. This natural selection eventually led to staph strains that are resistant to these antibodies.

Natural selection is a process of evolution by which those members of a species who live through catastrophe are thought to possess traits that help them survive. Through the survival of those members, these traits -- such as resistance to a disease -- pass from generation to generation. It's the reason you have an opposable thumb: As apes diverged genetically from Old World monkeys 6 to 8 million years ago, one of the results was the opposable thumb. As the thumb showed itself as a "handy" trait, it developed along with the primate family, which includes humans. The results are the human-dominated world we live in today -- thanks, in part, to our opposable thumbs.

The process of natural selection can takes tens (and in some cases, hundreds) of thousands of years to take place in humans. But this isn't the case for MRSA and some other bugs. As the Mayo Clinic put it, MRSA and other bacteria "live on an evolutionary fast track" [source: Mayo Clinic]. Rather than taking thousands of years to develop into their current lethal strain, MRSA has evolved -- and spread -- in mere decades. In 1974, MRSA infections made up two percent of all staph infections. By 2004, MRSA accounted for 63 percent [source: CDC]. What's worse is that this bug has been shown to be fatal in some cases, especially when it remains untreated.

One of the reasons for this is the bacteria's rapidly developing resistance to antibiotics. As its name implies, it's been resistant to Methicillin -- a penicillin-based antibiotic -- for some time now. But it's also showing resistance to other antibiotics, as well, and that has some physicians worried. MRSA can also be easily transferred from person to person, and two types of the bug have developed based on the setting where infection takes place.

So what exactly is this superbug, and just how do we fight it? In this article, we'll look at MRSA, and what -- if anything -- we can do to defeat it.


MRSA Infection

The rise of incidents of MRSA infections contracted in a health-care setting has caused some hospitals to invest in precautions like latex gloves that emit disinfectant.
Photo courtesy Joe Raedle/Getty Images

Methicillin-resistant Staphylococcus (MRSA, pronounced mer-sa) is just like any other staph bacteria. The difference is, this strain is particularly virulent -- meaning it's tough to kill and spreads easily. It can also be fatal.

Staph makes its way into the body through the skin. It can live in the skin or in the soft tissue after entering the body, but for most healthy people, it won't flourish. Our white blood cells and antibodies can usually kill the bacteria. Pre-existing flaws in the skin, such as cuts and abrasions -- which are already under attack from infectious bacteria -- can make defeating a MRSA infestation more difficult, however.


Once MRSA has found a foothold in the body, the place of infection will display what looks like small bumps, a pimple or a boil. The incubation period for MRSA varies, but usually it takes a few days before the infection takes hold. After the infection begins, these pimples or boils will begin to abscess -- meaning they will become hollow in the center and fill with infected fluid, such as pus.

This abscess can be very painful and can grow into the body, even reaching bone, deep tissue, the bloodstream and organs. Once the infection reaches internal organs or the bloodstream, the situation is life-threatening. A patient with a MRSA infection of this magnitude can suffer toxic shock (which affects the functioning of some organs), endocarditis (an inflammation of the heart's lining) pneumonia and even blood poisoning.

There are a number of signs and symptoms of MRSA infection that occur within the period from infection to severe illness, however. In other words, a MRSA infection doesn't go from zero to death in a short time. A person with a MRSA infection will notice the worsening skin irritations, as well as possibly a warm sensation around the infected area. He or she may also experience a fever.

Once the organs become infected, much more serious symptoms will appear. Chest pain, chills, joint pain and shortness of breath will all tell the sufferer that there's something terribly wrong.

One of the problems with MRSA is that it's easily spread. In fact, MRSA may be hitching a ride in your body right now without you knowing it. This is because some healthy people can serve as home to the bug without showing symptoms. An estimated 423,000 people annually are in a state of MRSA colonization without infection [source: Mayo Clinic]. MRSA can ride along in the soft tissue in the nose or on the skin.

The hospital is one of the main sites where a person can become infected with MRSA. Infections from hospital stays are so prevalent, in fact, that it's been identified as one of two sources for infection. Hospital- (or health-care-) associated MRSA (HA-MRSA) describes a type of MRSA that has evolved within the health-care setting. When it's determined that a patient in the hospital has a MRSA infection (or is colonized by the bacteria), he'll be quarantined and given a battery of antibiotics.

It's ironic that the hospital is one of the main settings for MRSA infections because this is the place where people who develop Community-associated MRSA infections go to be treated. CA-MRSA infections come from skin-to-skin contact with an infected or colonized person outside of the hospital setting.

But if hospitals are the setting for so many MRSA infections, should a person who suspects infection stay away? Certainly not. The hospital is still the place to go for MRSA treatment. Read the next page to find out how MRSA can be treated.


MRSA Treatment

Physicians may choose to lance a MRSA boil rather than prescribe antibiotics.
Photo courtesy Bruno Coignard/Jeff Hageman/Centers for Disease Control

Beating MRSA starts with proper diagnosis. When physicians properly prescribe antibiotics and patients take the entire prescription, MRSA has less chance to mutate.

MRSA diagnosis goes beyond a quick once-over. If you think you have a MRSA infection, you should visit your doctor. He or she will take a biopsy -- the removal of a small bit of skin and soft tissue -- of the infected area and send it off for examination at a lab. Lab technicians try to grow the bacteria from the tissue sample. Within 48 hours, the results will be clear. One emerging test, CHROMagar -- a method that uses more sensitive equipment than traditional methods -- can predict with 95.4 percent accuracy whether MRSA is present in a tissue culture after just 24 hours.


Once a test comes back positive for MRSA, your physician will most likely prescribe a strict regimen of antibiotics. The powerful antibiotic vancomycin has been shown to be effective against MRSA. It should be said, however, that some hospitals have reported strains of MRSA that are resistant to vancomycin. Although MRSA has become resistant to many traditional antibiotics, modern medicine still has some powerful weapons in its arsenal. What's more, they're applying antibiotics much more deliberately than in the past, meaning that when they administer them against MRSA, they're making sure they kill every last bit of it. No survivors means no mutated strain that can live on and prosper.

But physicians have other methods of treating MRSA as well, some very low-tech. To prevent misuse or overuse of antibiotics, some physicians are lancing the infected boils and treating the infections externally instead of with drugs.

This method raises its own problems, however. Medical equipment -- even if it's sterile -- can introduce the infection on the skin into the body, causing more MRSA infections. But taking the extra precaution of sanitizing the skin around the infection before it's pierced has been shown to prevent this type of infection.

Strangely, treatment for MRSA may end up coming from a very unlikely place -- underground. Researchers are taking a second look at a very old cure, clay, which has been used for millennia as a folk medicine treatment for a variety of ailments. In early testing, a type of French clay has been shown to kill MRSA bacteria, as well as Mycobacterian ulcerans -- also known as the flesh-eating bacteria. Honey can also be used to treat it.

Although the results have been positive, science has yet to figure out why the clay kills the bacteria. It could be awhile before the results are in: The research being conducted on clay's effects on MRSA and other bacteria is part of a two-year study at Arizona State University.

Meanwhile, the best way to beat MRSA is not to let it infect us. As Benjamin Franklin said, an ounce of prevention is worth a pound of cure. This is truer than ever, with hospitals serving as such a viable setting for MRSA outbreaks. Read the next page to learn how you can keep yourself out of the hospital and uninfected with MRSA.


MRSA Prevention

Simply washing your hands often can decrease your risk of becoming infected with the MRSA bacteria.
Photo courtesy Joe Raedle/Getty Images

So should we be panicking? Will the superbug end up leveling mankind? Perhaps it's a little early to declare anarchy or give away all of your favorite possessions -- we can still beat the superbug. Prevention is perhaps our best weapon in the fight against MRSA. Just taking some simple steps will greatly decrease your chances of infection.

Community-associated MRSA can be prevented in your everyday life. The key is not to go overboard. All of the antibacterial soaps and lotions that were supposed to protect all of us from germs and bugs have actually helped MRSA become such powerful bacteria.


  • In the gym: Keeping those personal items that touch your skin all to yourself is a good place to start. Don't let other people borrow your razor, soap, or even towel. If you go to the gym, don't wear the same clothes twice without washing them (use bleach in the load). It also doesn't hurt to take a shower before you leave the gym.
  • Cuts and scrapes: You can also prevent MRSA infections by cleaning cuts and scrapes with alcohol and properly bandaging them. Be sure to ask your doctor what kind of ointment to use -- antibacterial ointments may only make the MRSA problem worse.
  • Clean hands: Simply washing your hands helps, too. Throughout the day we touch all manner of things other people have touched: ATMs, doorknobs, flush handles on toilets. It's a good idea to wash your hands as often as possible. The Mayo Clinic also recommends you sanitize your hands with a liquid or gel sanitizer that's at least 62 percent alcohol. This comes in handy whenever there's not a restroom nearby.

It's also important to have yourself screened if you think you may have a MRSA infection. Stopping the infection before it spreads too deeply greatly increases your chances of avoiding a life-threatening situation.

Infections contracted within a health-care setting make up around 85 percent of all MRSA cases [source: CDC]. An estimated 1.2 million people become infected with MRSA annually during a hospital stay [source: Mayo Clinic]. It's a good idea to make sure the people who are helping you get well don't accidentally make you worse.

  • Your health-care worker: Hospitals house sick people, and health-care workers can easily spread MRSA through improper hand washing. Don't be afraid to ask your healthcare provider to wash his or her hands whenever she touches you. Be sure the workers use alcohol-based disinfectants and soap.
  • Treatment devices: You can also get a leg up on MRSA by making sure that any type of instrument the hospital uses for your treatment or care is sterile. When health-care workers use an instrument for an invasive procedure -- such as dialysis -- ask them to disinfect the area around the point of entry with alcohol.
  • A nice bath: If you're bedridden, you can request to be bathed with disposable cloths and disinfectant instead of reusable towels and soap and water.


Lots More Information

Related HowStuffWorks Articles

More Great Links


  • "Fight Against MRSA." University of Warwick. October 15, 2007.
  • "French Clay Can Kill MRSA and 'Flesh-Eating' Bacteria." Science Daily. October 26, 2007.
  • "Kaiser Daily Health Report." The Kaiser Family Foundation. June 25, 2007.
  • Klevins, Monina R., et al. "Invasive Methicillin-Resistant Staphylococcus Aureus Infection in the United States." October 17, 2007.
  • "MRSA Infection." Mayo Clinic.
  • "MRSA: Methicillin-Resistant Staphylococcus Aureus in Healthcare Settings." Centers for Disease Control. October 17, 2007.
  • "Performance of CHROMagar MRSA Medium for Detection of Methicillin-Resistant Staphylococcus Aureus." National Institute of Health. April 2005.
  • Stahl, Leslie. "Super-Resistant CBS News May 2, 2004. Superbugs."