Researchers not sure what is causing decline in staph infections in military

Staph infections among people in the military declined during a 6 year period between 2005 and 2010, according to a report published Wednesday in the Journal of the American Medical Association.

The study looked at more than 9 million active duty and non-active Department of Defense personnel and found that cases of methicillin-resistant Staphylococcus aureus or MRSA dropped significantly in both community and hospital settings.

"This study is important because it's expanding on previous studies that only looked at either MRSA bacterimia in a hospital setting or focused on smaller regions in the United States," said Dr. Clinton K. Murray, a study author and chief of Infectious Disease Service at Brooke Army Medical Center/San Antonio Military Medical Center.

"So with the DOD population we could look at 266 facilities spread across the U.S. as well as overseas. And even though we're a military population, only 15% of people in the study were active duty. The other 85% were families, retirees or retiree family members."

MRSA is a highly contagious bacteria that is resistant to some of the first-line, antibiotics like methicillin, penicillin, amoxicillin and oxacillin. Community-onset MRSA infections usually occur outside of a health care setting. Most are skin infections that are spread through skin to skin contact. In the beginning they look like a spider bite, can appear to be a bump or boil - red, swollen and painful.

According to the CDC, most community acquired infections are often treated without any long-term problems.

But hospital-onset MRSA can be deadly. These infections get into the bloodstream, and they can occur at the site of a surgery. They can cause MRSA-related pneumonia, spread to the bone, or major organs like the heart, lungs and brain. In a hospital, health care providers or even visitors can have staph germs on their bodies that can then be spread to a patient.

The study also found methicillin-suceptible Staphylococcus aureus or MSSA also decreased in the military. MSSA is considered to be less serious than MRSA.

"The big difference is with MSSA you can use commonly used antibiotics. With MRSA, you've lost a relatively large number of antibiotics that are no longer effective against the bacteria causing the infection."

Murray says about 1% to 3% of healthy people have MRSA on their bodies. Approximately 30% have MSSA, but that doesn't mean they'll become infected.

The researchers say skin and soft tissue infections or SSTIs are often caused by MRSA and MSSA. These infections are also seen in large numbers and present a major public health concern for the military. Staph is a leading cause of infection in healthy people in the community and the leading cause of infections picked up in the hospital.

"These infections can be hard to treat, and there is no universal way to prevent staph infections like a vaccine," Murray said. "In a study from 2007, it was estimated that MRSA alone was responsible for nearly 100,000 deaths in the U.S."

According to the study, community-onset MRSA rates were higher in people 65 years or older. These infections happened more often in men. Hospital acquired infection rates were highest in patients 4 years old or younger, and 65 or older, and were also higher in men.

The CDC says hospital-related MRSA is also declining in the general population but not at the rate seen in the military.

The agency says good personal hygiene can help prevent these infections. The CDC recommends keeping your hands clean and keeping cuts and scrapes clean and covered until they've healed. In a hospital setting those providing patient care should adhere to the hospital's infection prevention guidelines.