A drug-resistant form of the bacteria that causes staph, Staphylococcus aureus, has been rapidly spreading worldwide and might become an even bigger problem in the future, researchers report online in The Lancet.

The drug-resistant bug can cause infections in various parts of the body. While most aren’t serious, some can be life-threatening.

Millions around the world are already infected with the drug-resistant strain, which is spread by contact with infected people or contaminated objects. Those with weak immune systems and living in hospitals, nursing homes, and other health care centers are most vulnerable.

The scientists behind the Lancet report have been studying methicillin-resistant Staphylococcus aureus (MRSA), named for the antibiotic methicillin. They include Hajo Grundmann, MD, of the Centre for Infectious Disease Epidemiology in the Netherlands.

The researchers call for countries to step up their MRSA surveillance and prevention efforts, especially in hospitals, saying infections have been “swiftly increasing worldwide over the past decades.” If certain strains of MRSA take root in communities, “the MRSA situation in hospitals, which still remains out of control in many countries, could potentially become explosive,” Grundmann and his colleagues warn.

About MRSA

Staph itself is a very common – and often harmless -- infection. Only a small fraction of those with staph have the drug-resistant kind.

“Of the expected 2 billion individuals carrying S. aureus worldwide, conservative estimates based on either Dutch or U.S. prevalence figures would predict that between 2 million and 53 million carry MRSA,” write Grundmann and colleagues.

But MRSA’s resistance to antibiotics can make it a serious, difficult-to-treat,problem.

The bacteria was discovered in 1961 and is now resistant to the antibiotics methicillin, amoxicillin, penicillin, and oxacillin. While it doesn’t resist all drug treatments, it’s been quick to adapt to new ones.

MRSA infections are most common among people with weak immune systems living in health care centers. Infections can appear around surgical wounds or invasive devices, such as catheters or implanted feeding tubes.

But MRSA has also shown up in healthy people who haven’t been hospitalized, in what is called community-acquired MRSA.

Community-acquired MRSA is relatively rare. If it becomes common, it could worsen hospitals’ MRSA situation, Grundmann’s team predicts.

“MRSA is at present the most commonly identified antibiotic-resistant pathogen in many parts of the world, including Europe, the Americas, North Africa, the Middle East, and East Asia,” write Grundmann and colleagues.

Since countries don’t monitor MRSA, Grundmann’s team made their own global estimate, coming up with the 2 million to 53 million figure.

MRSA Symptoms

Symptoms depend on the part of the body affected.

MRSA most often appears as a skin infection, like a boil or abscess. It also might infect a surgical wound. In either case, the area would be swollen, red, painful and filled with pus.

Many people with a staph skin infection mistake it for a spider bite.

Staph that infects the lungs and causes pneumonia can lead to shortness of breath and fever chills

MRSA can cause a myriad of other symptoms since it can also infect the urinary tract or the bloodstream.

Very rarely, staph can result in necrotizing fasciitis, or "flesh-eating" bacterial infections. These are serious skin infections that spread very quickly. While frightening, necrotizing fasciitis caused by staph is rare, with only a handful of reported cases.

Prevent MRSA Infection

To prevent MRSA infection, the CDC’s recommends the following:

--Wash your hands. Use soap and water or an alcohol-based hand sanitizer. It’s important to wash thoroughly. Experts suggest you wash your hands for as long as it takes to recite the alphabet.

--Cover cuts and scrapes with a clean bandage. This will help the wound heal as well as prevent the spread of bacteria to other people.

--Do not touch other people's wounds or bandages.

--Do not share personal items such as towels or razors. If you use shared gym equipment, wipe it down before and after you exercise.

--Drying clothes, sheets, and towels in a dryer, rather than letting them air dry, also helps kill bacteria.

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Grundmann, H. The Lancet, June 21, 2006; online edition. WebMD Medical Reference: “Understanding MRSA -- The Basics.” WebMD Medical Reference: “Understanding MRSA -- Symptoms.” WebMD Medical Reference: Understanding MRSA -- Prevention.” News release, The Lancet.