District officials have confirmed the fourth case of MRSA at Rocky Point High School.
A student is believed to have been infected following an off-school-property injury more than a month ago.
The district says the student was part of the same sports teams as those in prior cases, although it does not appear to be related.
MRSA is a staph infection that is resistant to many common antibiotics.
District officials say they will sanitize the entire building in response.