Two students in the North Hills School District have contracted methicillin-resistant Staphylococcus aureus, or MRSA, according to a letter posted on the district's Web site.

One student attends North Hills Junior High School, and the other attends North Hills Senior High. Both students have been treated by their doctors, according to the letter.

MRSA is a bacterial infection that commonly causes redness, boils, swelling or areas that are warm to the touch and painful. The infection is resistant to antibiotics and is best prevented through diligent personal hygiene, such as frequent hand-washing, showers and laundry.

It is commonly spread among athletes, and one of the North Hills students does play school sports, said Tina Vojtko, communications coordinator for the district.

From January through October, Allegheny County had 132 reported MRSA cases, 68 of which occurred in people 18 and younger, said Guillermo Cole, spokesman for the county's health department. At least 18 school districts, encompassing 24 or more schools, have seen MRSA cases this year, he said.

The county's Board of Health voted Wednesday to start requiring reporting of MRSA from all county physicians; previously, only pediatricians were required to report MRSA cases.