Scientists at the Centers for Disease Control and Prevention are investigating a troubling increase in children dying from staph and MRSA pneumonia after battling flu infections.

Chelsie Glenn, an 11-year-old from Athens, and Christopher Fouts, a 13-year-old from Griffin, are two of the children whose deaths last year contributed to CDC's concern, records show.

Both went from being healthy children running around in their separate communities to having what seemed to be a typical cold — to dying, all within a few days.

"We went shopping that Thursday, and that Sunday she was gone," said Melissa Mize-Elder, Chelsie's mother. "I didn't understand how it was she was so well, and then suddenly she died."

The children died on consecutive days in 2007: Chelsie on Feb. 11 and Christopher on Feb. 12.

At least 22 of the 73 U.S. children who were documented to have died of influenza during the 2006-07 flu season also had a staph infection — a five-fold increase over previous years, according to the CDC.

Fifteen of them had the drug-resistant staph strain MRSA.

Scientists are examining whether the flu allows MRSA to invade the lungs or whether some staph strains have developed increased virulence.

In January, the CDC issued a national alert urging doctors to be on the lookout for children infected with both flu and staph.

Life-threatening MRSA infections remain rare in the community, experts said. Deaths of healthy children like Chelsie and Christopher are rarer still.

Concerned about Chelsie's high fever, Mize-Elder took her daughter to St. Mary's Hospital on Feb. 10, 2007. A test showed she had influenza, and doctors sent her home with prescriptions for Tamiflu and cough syrup, records show.

Early the next morning, Chelsie was much worse, and they headed back to the hospital. In the car, Chelsie asked: Am I going to die? "I said, no, they're going to help you," her mother recalled.

Then Chelsie collapsed and stopped breathing. She died as medics tried to airlift her to a children's hospital in Atlanta.

Christopher's death stunned his family as well as his tiny Grace Fellowship Christian School.

He stayed home from school on Thursday, Feb. 8, 2007. His dad took him to a local clinic: "They said he just had a cold," Betty Mayo, Christopher's grandmother, recalled.

Over the weekend, Christopher still wasn't feeling great but was well enough to play with other kids at a church gathering and go out to eat with his dad and grandfather.

When he woke up Monday morning, Christopher's father found the boy unconscious. Paramedics couldn't revive him. "They did everything they could," said Donald Fouts, Christopher's grandfather. Christopher and his father lived in an apartment behind Donald Fouts' house.

Christopher's family said they had been left wondering why the boy died. Nobody told them about MRSA, until the AJC recently showed them his autopsy report.

The family had suspected a recall of contaminated peanut butter.

Last year, flu shots weren't recommended by CDC for children their age. They now are, though scientists don't know whether flu shots would have prevented the deadly flu-MRSA infections.