A southern Virginia school district closed its 21 schools for cleaning Wednesday after a 17-year-old high school senior died Monday from what his mother said was adangerous strain of staph infection.

The Bedford County school district has not yet received medical confirmation the boy had the drug-resistant form of staph called MRSA, but six other cases of MRSA have been confirmed in the district since school began in late August, Superintendent James G. Blevins said.