USA300 invades a nursing home

A study in this month's Emerging Infectious Diseases analyzes the molecular epidemiology of MRSA infections over a 10 year period (1997-2006) at a 1,000 bed long-term care facility in San Francisco. Of the nearly 1,300 patients with S. aureus clinical isolates, 58% were methicillin resistant, with an increase to 72% methicillin resistance in 2006. Most notably, in 2002 11% of MRSA isolates were the USA300 clone with a sharp rise to 64% in 2006. The majority of USA300 strains were associated with skin/soft tissue infections. Given the high rates of transfer of patients between LTCFs and acute care hospitals, the implications of this study are very important, and we must be concerned with how widespread this problem is beyond the LTCF studied.