Combating MRSA: The drug-resistant “superbug”

Bacteria that don’t succumb to the usual antibiotics give everyone the jitters. But there’s a lot we can do to keep the upper hand.

Few achievements in modern medicine can rival Alexander Fleming’s discovery of penicillin in 1928, which began a cascade of antibiotics that cure infections and save lives. But the widespread use of these lifesaving drugs has led to the rise of drug-resistant bacteria, or “superbugs,” which are outwitting even our newest and most powerful antibiotics.

In the fall of 2007, we learned that one such bug — methicillin-resistant Staphylococcus aureus (MRSA) — is much more common than experts had thought and already causing thousands of deaths each year in the United States. Researchers with the Centers for Disease Control and Prevention provoked a wave of public anxiety when they reported in the Journal of the American Medical Association (Oct. 17, 2007) that MRSA — once largely confined to health care settings — is becoming prevalent in the broader community.

MRSA belongs to a genus of bacteria — more than 30 types — called Staphylococcus, or just “staph.” Staphylococci are found in about 30% of adults, mostly on the skin or in the nose. Most people who carry the bug are healthy; they are said to be “colonized” but not infected. Most infections occur when one type of staph — Staphylococcus aureus — gets into the body through a break in the skin, such as a cut or burn. Even then, it usually causes only minor symptoms, such as small pimples or boils that can be treated without antibiotics. But staph infection can be very serious for people whose immune systems are weakened by age, illness, or chemotherapy. They may develop a deep abscess or life-threatening infection in the bloodstream, urinary tract, lungs, or surgical wounds.

Most serious staph infections can be successfully treated with methicillin, which belongs to the penicillin class of antibiotics. MRSA infections are resistant to this group of antibiotics, but they usually do respond to other, more potent antibiotics, particularly vancomycin. The trouble is that it may take a day or two to determine whether a given infection is caused by ordinary staph or MRSA. Because of the delay, patients infected with MRSA have longer hospital stays and worse outcomes, including higher death rates, than those with staph infections that are not resistant to methicillin.

MRSA first appeared in the 1960s in hospitals and health care facilities such as nursing homes and dialysis centers. It occurred mostly in people who had weakened immune systems, were treated with multiple antibiotics, or had undergone procedures that punctured the skin (intravenous catheters or surgery). For a while, serious MRSA infections were confined mostly to inpatient settings. But in the 1990s, a type of MRSA began to appear among otherwise healthy people who hadn’t been recently hospitalized or undergone an invasive procedure. This form of MRSA tends to spread among people who live in crowded conditions or have close skin-to-skin contact — especially when they are exposed to cuts and abrasions as a result. Athletic facilities, prisons, and child care centers are all likely sites for community-acquired MRSA. The infection is also spread by poor personal hygiene, such as infrequent hand washing, and by the habit of sharing contaminated items, such as towels or razors.

Both health care– and community-associated MRSA are on the rise. In hospitals and other health care facilities, MRSA is now responsible for 20% of bloodstream infections and, according to a 2003 study, for up to 64% of staph infections. In 2007, researchers at a Veterans Affairs hospital in Texas reported that the incidence of MRSA isolated from patients with complicated skin and soft-tissue infections increased from 34% in 2000 to 77% in 2006. And since its emergence, community-associated MRSA has become the most frequent cause of skin and soft-tissue infections among people visiting emergency rooms. Until recently, community-associated MRSA caused mostly simple skin infections, but now, especially in people with weakened immunity, it has begun to cause invasive infection — that is, serious infections in the blood or other internal locations.

Hospitals and other health care facilities must enforce strict rules on hand washing and the use of gloves. They must use antibiotics and invasive devices more prudently, survey patients and staff regularly for MRSA, isolate patients with MRSA infection, and make sure the environment is clean. Biomedical researchers are working on measures that range from gloves that release disinfectants to antibiotic-coated catheters — and, of course, new antibiotics. In January 2008, the FDA approved a blood test that allows doctors to start treating MRSA infections earlier by identifying them within two hours rather than two days.

There’s a lot that we can do as individuals to protect ourselves from health care–acquired MRSA infection. If you’re hospitalized, make sure hospital staff have washed their hands or used alcohol-based hand sanitizer every time before they examine you. Wash your own hands frequently. Before an intravenous catheter is placed, make sure that your skin is sterilized and the person inserting the catheter is wearing gloves. If you visit a patient in the hospital, always wash your hands before entering the room and before leaving. Observe any precautions requested by hospital staff, such as wearing a gown, gloves, or a mask.

You can also do a lot to protect yourself from MRSA in the community. Wash your hands frequently and thoroughly throughout the day with soap and water. Carry a small bottle of hand sanitizer for times when you don’t have access to soap and water. Don’t share personal items such as razors, towels, sheets, and athletic clothing or equipment. Keep cuts or scrapes clean, and cover them with a bandage. Shower after you work out. Wash your gym clothes every time you wear them. Wash sheets and towels in hot water and dry them in a hot dryer. Take any prescribed antibiotic exactly as directed, and take all of it. Don’t save unfinished antibiotics for another time.

Health Letter

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