Doctors diagnosed a sixth-grader and an eighth-grader at the middle school with methicillin-resistant Staphylococcus aureus, or MRSA, said Sue Berg, Mt. Diablo school district spokeswoman.
A third suspected student infection was determined not to be MRSA. However, Sequoia Elementary School reported Friday that a second-grader had contracted a case of the infection. The district notified parents of students at those schools with automated phone messages.
The additional infections, caused by a relatively common but potentially fatal bacteria, have alarmed parents.
"I'm not panicked, but I'm highly concerned," said Denise Lowry, who has two daughters at the middle school.
After the first case, Lowry says her family became more vigilant about hand-washing and covering wounds. The girls also asked Lowry to buy them alcohol-based hand sanitizer, which they tote in their backpacks.
"They've all decided it's in their best interest to carry Purell with them," Lowry said.
S. aureus represents one of a number of bacteria ordinarily found on skin or in nasal passages. Some strains have developed resistance to common antibiotics.
While doctors and public health officials long have wrestled with the drug-resistant variety, the germ recently reached the national consciousness after an infection killed a high school football player in Virginia.
Around the same time, the Journal of the American Medical Association published a study recognizing MRSA as a serious emerging public health problem that is increasingly found outside of hospitals.
Public health officials stress that the best way to avoid any staph infection is to practice good hygiene, which includes frequent, thorough hand-washing and showering after sports games or practice.
"That's going to be everyone's best defense," said Susan Farley, a public health nurse with Contra Costa County's communicable disease program. At schools with known cases, like Sequoia, cleaning should cover surfaces where those infected would have made contact.
However, some parents worry that washing hands or desks won't be enough.
Sheila Hill's father died from a MRSA infection. A parent of a sixth-grader at Sequoia Middle School, Hill is considering pulling her child from class as she said other parents have done.
"I might keep my son home tomorrow while they get things under control," Hill said Tuesday.
Farley said only students who are sick should stay home.
"It's really kids who have active, draining lesions that shouldn't be at school," Farley said, "not kids who are well."
Shirley Dang covers education. Reach her at 925-977-8418 or firstname.lastname@example.org.
TO PROTECT YOURSELF