WEDNESDAY, May 16, 2012 (HealthDay News) -- A dangerous antibiotic-resistant "superbug" appears to originate in hospitals in large cities and then spreads to smaller hospitals, according to a new study.
Researchers at the University of Edinburgh in Scotland analyzed the genetic makeup of more than 80 variants of a major clone of methicillin-resistant Staphylococcus aureus (MRSA) bacteria found in hospitals.
Their findings are published in this week's online edition of the Proceedings of the National Academy of Sciences.
"We found that variants of MRSA circulating in regional hospitals probably originated in large city hospitals. The high levels of patient traffic in large hospitals means they act as a hub for transmission between patients, who may then be transferred or treated in regional hospitals," study leader Dr. Ross Fitzgerald said in a university news release.
Older patients and those with weakened immune systems are especially vulnerable to MRSA, according to the U.S. National Institute of Allergy and Infectious Diseases. Poor hand washing by health care workers and lack of good infection-control practices add to the problem.
In the new study, the investigators also found that the MRSA they studied evolved from antibiotic-sensitive bacteria that existed more than 100 years ago. MRSA first appeared about 50 years ago, after the introduction of antibiotics.
"Our findings suggest that the referral of patients to different hospitals is a major cause of MRSA transmission around the country. This knowledge could help in finding ways to prevent the spread of infections," study first author Paul McAdam, of the university's Roslin Institute, said in the news release.
The U.S. Centers for Disease Control and Prevention has more about MRSA.