Many Are 'Carriers' of Drug-Resistant Staph Bacteria

Considered a "silent epidemic" by some public health experts, antibiotic-resistant staph infections are a growing threat to public health.

Almost 1 percent of the U.S. population -- about 2 million people -- carry drug-resistant staph without symptoms. The medical name for the infection is methicillin-resistant staphylococcus aureus, or MRSA.

Here's what you need to know about MRSA:

What exactly is MRSA?

MRSA is a kind of bacteria that causes staph infections. Because it is resistant to many antibiotics, MRSA can be very difficult to treat, resulting in major infections and even death.

How does someone get MRSA?

There are two major classifications of MRSA, depending on the route of infection: The more common one is hospital-acquired MRSA, in which patients are infected during medical treatment, and the other is community-acquired MRSA, in which patients are infected during their normal daily routines.

MRSA can live just about anywhere, from medical equipment to grass in the park. The bacteria enter the body wherever they can find an opening, from minor cuts to inhalation through the mouth or nose. Testing positive for MRSA does not automatically mean that you are sick. Around 1 percent of the population is a MRSA carrier, meaning the carrier can spread the bacteria without necessarily becoming ill.

How common is MRSA?

MRSA is becoming a bigger problem both in hospitals and in the community. The Centers for Disease Control and Prevention recently reviewed the prevalence of MRSA in intensive care units and found a dramatic increase over time. In 1992, 36 percent of the S. aureus bacteria in ICUs were MRSA, but by 2003, that number rose to 64 percent.

Using data from 1999 and 2000, the CDC estimates that more than 125,000 people a year are hospitalized for MRSA infection. People over age 65 or living in the southern part of the United States are most likely to be affected.

What happens when someone becomes infected with MRSA?

Hospital-associated MRSA is generally more serious because it often occurs in people who have weakened immune systems because of age (very young or very old) or illness. These patients frequently acquire MRSA infections at surgical sites, where it can spread to the bloodstream and cause damage to such organs as the lungs and heart.

In otherwise healthy people, MRSA generally shows up as a skin infection. It can cause painful swellings and growths that may require surgery.

In rare instances, MRSA has been associated with "flesh eating" bacterial disease, in which tissue begins to decay rapidly upon infection. These patients can require amputation of an arm or leg to prevent the bacteria from spreading to other parts of the body.

How is MRSA treated?

MRSA is generally treated with some combination of antibiotics and surgery, depending on where the infection is. Although MRSA is resistant to some forms of antibiotics, it's not usually able to escape them all. The newer antibiotic vancomycin is often a current choice in treating MRSA, but the bacteria are now showing some signs of becoming resistant to this drug too.

Minor skin infections with MRSA may just be drained and cleaned.

How did MRSA become resistant to antibiotic treatment?

Bacteria generally start showing resistance fairly quickly to any medication that's designed to defeat them. Most often, a mutation in the bacteria allows it to survive the drug treatment, and these surviving bacteria create many more copies of themselves that are also resistant.

Scientists are trying to stay one step ahead of the bacteria by creating new drugs to defeat them. The public can help slow down bacterial resistance by not using any unnecessary antibiotic medications. For example, studies have shown that most cases of ear infection and bronchitis do not need to be treated with antibiotics. By refraining from antibiotic use in unnecessary situations, people help preserve the drugs' effectiveness for when they are truly needed.