SANDY SPRING, Md., Oct. 18 — When the football players here at Sherwood High School were not getting the message about washing their uniforms and using only their own jerseys, the school nurse paid a surprise visit to the locker room. She brought along a baseball bat.

“Don’t make me use this,” the nurse, Jenny Jones, said, pointing out that seven players on the team had already contracted a deadly drug-resistant strain of bacteria this year. “Start washing your hands,” she said. “I mean it.”

School officials around the country have been scrambling this week to scrub locker rooms, reassure parents and impress upon students the importance of good hygiene. The heightened alarm comes in response to a federal report indicating that the bacteria, methicillin-resistant Staphylococcus aureus, or MRSA, are responsible for more deaths in the United States each year than AIDS.

MRSA (pronounced MEER-suh) is a strain of staph bacteria that does not respond to penicillin or related antibiotics, though it can be treated with other drugs. The infection can be spread by sharing items, like a towel or a piece of sports equipment that has been used by an infected person, or through skin-to-skin contact with an open wound.