A water accident like the Georgia case led to the infection.

http://www.startribune.com/nation/174048821.html
Teen recovers from flesh-eating disease that nearly took her leg - and her life

Article by: VALERIE STRAUSS , Washington Post
Updated: October 13, 2012 - 8:20 PM

At 16, Alexis Hanford is recovering from a flesh-eating disease after 17 surgeries to save her leg - and her life.
[snip]
On July 25 near Ukiah, Calif., Alexis and her family were enjoying a family reunion in a remote area. Alexis dropped from a tree swing into a lake and a tree gashed her left leg.

At a hospital, doctors pulled wood from the wound, cleaned the area and stitched her up. Days later, she was back in Bethesda when the skin around her leg turned colors and swelled. "My leg burst. ... My pain level went from a 3 out of 10 to 10 out of 10 in a second and started rising from there," Alexis said...