OKLAHOMA CITY (AP) - Bacteria found under the long fingernails of two nurses may have contributed to the deaths of 16 sickly babies in 1997 and 1998 in an Oklahoma City hospital, researchers say.

All of the babies were newborns in the neo-natal intensive care unit at Children's Hospital of Oklahoma, and all had infections caused by the same bacteria found under the nurses' nails.

However, researchers said they cannot be certain that the nurses transmitted the bacteria to the infants. And the hospital pointed out that the babies - most of whom were premature - had seriously deficient immune systems, and said that other problems played a larger role in their deaths.

Nevertheless, the hospital has changed its policy to require short fingernails on nurses, and no babies in the neo-natal ICU have died from the bacterial infection since then.

The findings were reported in the February issue of the Infection Control and Hospital Epidemiology Journal. The study was done by the state Health Department, the hospital and the Centers for Disease Control and Prevention.

"We felt like the connection was strong enough to report it," said state epidemiologist Dr. Michael Crutcher, who helped write the study. But he added: "There was no way to definitively prove that this was the mechanism of transmission."

Dr. William Jarvis, chief of the investigation and prevention branch of the CDC's hospital infection program, said the agency has investigated two or three outbreaks over the past 10 years in which fingernails were thought to have played a role.

But like the Oklahoma hospital, Jarvis suggested that other factors were at play. "In all of these with data to support that fingernails have been the critical element, it hasn't been the only element," he said.

The bacteria, pseudomonas aeruginosa, can be found in every hospital nursery in America, said Dr. Roger Sheldon, medical director of the hospital.

The death rate in the hospital's neo-natal ICU is close to the national rate, but at one point, the staff noticed an increase of approximately one death per month. The hospital called the CDC, which studied the records of all the babies who had been in the unit in 1997 and the first three months of 1998.

Of 439 newborns admitted during that period, 46 acquired the bacterial infection and 16 died.

The study found evidence of an association between the bacteria and exposure to two nurses with long or artificial fingernails. The bacteria were also found on two sinks and fingernails of another nurse with short, natural nails, but that nurse was not linked to the infection in the infants.

The CDC suggested improved hand-washing and requiring nurses to have short, natural fingernails, which are considered less likely to harbor germs.

Yvonne Sibley, head nurse in the neo-natal ICU, said all nurses in the hospital must now have nails that are considered piano-playing length.

Crutcher, the state epidemiologist, said at no time was there negligence on the part of hospital personnel.

The newborns in the neo-natal ICU are mostly premature and may weigh as little as a pound, or were born to mothers with drug habits, said Gay Conner, a hospital spokeswoman.

"Just because of the nature that they're in NICU, already their immune systems are compromised," Conner said Thursday. "Fifty percent of the ones who died would have died from something else."

Added Sheldon, the hospital's medical director: "These children didn't die of infection. They died of being born way too soon."

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