Researchers at the University of California, San Francisco, say data from the National Center for Health Statistics for patient visits for skin infections from 1997 to 2005 show a rise from 8.6 nationwide to 14.2 million.

They also report an increase from 4.6 million to 9.6 million in visits for abscesses or cellulitis -- the hallmark sign of infections due to MRSA bacteria. The findings are published in the Archives of Internal Medicine.

"The vast majority of that increase was attributable to visits for abscesses or cellulitis," study lead author Dr. Adam Hersh says in a statement. "This shows that community-acquired MRSA infections are occurring nationwide and affect all subsets of the population. But there clearly are some subsets that are disproportionately affected, such as children."

The number of visits for abscesses or cellulitis almost tripled in children during the study period.

Another increase in visits for abscesses or cellulitis was among patients who visit emergency rooms in urban areas at so-called safety net hospitals -- where many patients receive Medicaid or are uninsured. Among these patients, the rate nearly quadrupled.