ATLANTA, May 24 (Reuters) - A Georgia graduate student fighting a rare flesh-eating bacterial infection she contracted after being injured in a zip-line accident is now able to sit in a chair for hours at a time, her father said.

"When the doctors put Aimee up in that chair, their expectations were to give her an hour," Andy Copeland wrote in a Facebook posting Thursday. "Five hours later, Aimee decided it was time to lie down. Had she been running an Olympic marathon, I think Aimee would have experienced a record-breaking, gold-medal moment."

The struggle to save 24-year-old Aimee Copeland from necrotizing fasciitis -- a bacterial infection that can destroy muscles, skin and tissue -- has been chronicled by her father on Internet postings.

Copeland, a student at West Georgia University, slashed her calf when the zip-line snapped May 1 along the Little Tallapoosa River near Carrollton, Georgia. Emergency room doctors closed the wound with 22 staples and released Copeland, but she was diagnosed with the infection after her conditioned worsened.

Surgeons amputated Copeland's left leg at the hip. Last week, she mouthed, "Let's do this" when told her hands and remaining foot would also have to be amputated, her father wrote on Friday.

Aimee remains in critical condition, Barclay Bishop, spokeswoman for Doctors Hospital in Augusta, said Thursday.

A 1996 report from the U.S. Centers for Disease Control and Prevention estimated there were 500 to 1,500 cases of necrotizing fasciitis annually in the United States, with about 20 percent of them fatal. The National Necrotizing Fasciitis Foundation has said that estimate is probably low.

Earlier this week, Aimee's father reported that she was able to breathe on her own without a ventilator. The latest improvement, sitting up in a chair, was prompted Tuesday when Aimee asked to go out in the hall with a nurse.

"'Honey, you have wires and tubes coming out of your body. I just can't pick you up,'" Aimee's mother, Donna, told her, according to the Facebook post by Andy Copeland.

Donna Copeland, however, asked a nurse if Aimee could sit up in a chair and doctors agreed. There were fewer tubes attached to Aimee at the time because doctors had temporarily taken her off a dialysis machine to see how her body would respond. Also, she was not connected to the ventilator, Andy Copeland wrote.

"Although the lines running to her body were many, there were fewer to hassle with than there were thirty-six hours prior," the father said.

As Aimee sat in a chair, a country music artist, Corey Durkin, played a song he wrote for her, entitled "Southern Belle" Andy Copeland wrote.

After the private concert was over, Aimee mouthed a few words that Durkin could not understand. Andy Copeland interpreted: "Thank you very much from the bottom of my heart! I really, really appreciate it!" (Reporting by David Beasley; Editing by Greg McCune)

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