The number of persons who have serious, and often termed "invasive," infections with methicillin-resistant Staphylococcus-aureus (MRSA) in the U.S. is much greater than originally estimated, according to a study reported in the Oct. 17, 2007 issue of the Journal of the American Medical Association.
The study is the first to provide a population-based measure of invasive MRSA infections. Using results from nine U.S. metropolitan community sites participating in the Active Bacterial Core surveillance (ABCs)/Emerging Infections Program Network from July 2004 to December 2005, researchers at Centers for Disease Control and Prevention (CDC) studied thousands of MRSA infections.
The scientists found that in about 27 percent of the cases, persons got the infections while patients in hospitals. About 14 percent got the infection in the community. And about 58 percent got the infection after a healthcare encounter, such as hospitalization or surgical procedure.
"In the community Staphylococcal infections, including MRSA, generally start as red bumps or boils," says study co-author Susan Ray, MD, associate professor of Medicine at Emory University School of Medicine, and co-author on the report. These can quickly turn into deep, painful abscesses that require surgical drainage. A small proportion of patients with MRSA skin abscesses will develop invasive disease, such as the infections noted in the study."
MRSA accounts for the most frequent cause of skin and soft tissue infections presenting to emergency rooms in the U.S. In hospitalized patients, MRSA has been a problem since the 1960s and is associated with greater lengths of stay, higher death rates and increased costs.
"These infections were mostly seen in hospital settings but that is changing as we are beginning to see more community onset cases - and what that means is these old diseases are learning new tricks, essentially becoming drug resistant," say Dr. Ray, associate hospital epidemiologist at Grady Health System in Atlanta.
Staph bacteria can be found in the normal flora on the skin in about one-third of the population. If a person has staph on the skin or in the nose but is not feeling ill, it is considered to be "colonized" but not infected with MRSA. Healthy persons can be colonized with MRSA and have no ill effects, however, they can pass the germ to others.
Risk factors include:
- A current or recent hospitalization. MRSA remains a concern in hospitals, where it can attack those most vulnerable - older adults and persons with weakened immune systems, burns, surgical wounds or serious underlying health problems.
- Residing in a long-term care facility. Carriers of MRSA have the ability to spread it, even if they're not sick themselves.
- Invtravascular devices. People who are on dialysis, or who have intravascular devices, for other reasons are at higher risk.
- Children. MRSA can be particularly dangerous in children, often starting as a minor skin abscess which can invade the bloodstream and lead to bone and joint infections and sepsis.
- Participating in contact sports. MRSA has crept into both amateur and professional sports teams. The bacteria spread easily through skin-to-skin contact and sharing of personal items like towels and razors.
- A weakened immune system. Persons with weakened immune systems, including those living with HIV/AIDS, are more likely to have severe MRSA infections.
What individuals can do to prevent MRSA:
- Wash your hands. In or out of the hospital, careful hand washing remains the best defense against germs.
- Ask all hospital staff to wash their hands before touching you - every time.
- Make sure that intravenous tubes and catheters are inserted and removed under sterile conditions
- Keep personal items personal. Avoid sharing personal items such as towels, sheets, razors, clothing and athletic equipment. MRSA spreads on contaminated objects as well as through direct contact.
- Keep wounds covered. Keep cuts and abrasions clean and covered with sterile, dry bandages until they heal. The pus from infected sores is loaded with harmful bacteria including MRSA. Keeping wounds covered will keep the bacteria from spreading.
The study was funded through the Emerging Infections Program, National Center for Preparedness, Detection, and Control of Infectious Diseases, Coordinating Center for Infectious Diseases, CDC.