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Human Touch May Be Key in Germ Deaths

Infections: Officials search for how bacterium entered a neonatal ICU, where already-weakened babies died.

September 23, 1997|ELIZABETH MEHREN | TIMES STAFF WRITER

BOSTON — With deadly efficiency, a powerful bacterium has claimed the lives of four young patients at one of this country's most prestigious children's medical facilities. The appearance of the virulent Pseudomonas aeruginosa organism at Children's Hospital here also forced the closure of the institution's neonatal intensive care unit where the lethal infections occurred.

The wave of cases took place over a six-week period in July and August. Public health officials were informed as soon as hospital officials became aware of the "unusual number" of infections, but a public announcement was not made until last week. The 9-year-old NICU facility at Children's was considered "beyond state of the art," said Dr. Edward J. O'Rourke, the hospital's medical director of infection control. With an average population of 16 to 24 infants, the unit boasted an unusually low annual fatality rate, about 4%, and had never been closed before.

Far from some exotic germ, P. aeruginosa is a common strain of bacteria found on many fruits and vegetables. The organism thrives in moist areas and water. In healthy children and adults, these bacteria seldom cause disease. But in severely ill patients with weakened immune systems, P. aeruginosa can cause death "within a few days," said Dr. Bela Matyas, an epidemiologist with the Massachusetts Department of Public Health.

All the victims at Children's were critically ill before they became infected, O'Rourke said. He said some fell into the "micro-preemie" weight range of under 1,000 grams at birth, making their survival questionable under the best of circumstances. Others were not low birth weight but nonetheless required intensive care support.

The bacterium in question typically produces severe pneumonia and an infection of the bloodstream. While it is not antibiotic-resistant, the patients who died at Children's were too small or too ill to be helped by antibiotics.

Precisely how the bacterium entered the unit remains under investigation. But O'Rourke said the very nature of an intensive care unit, where patients are tethered to tubes and monitors are passed through already weakened bodies, provided an ideal medium for transmission. Intensive care patients also are subject to near-constant involvement with hospital staff, who may themselves have come in contact with a potential agent of contamination.

"You can imagine that a single [intensive care] patient is probably touched by a health care worker 100 times a day, and that one health care worker is probably touching several patients," O'Rourke said. "Even if that worker is scrupulous--batting .1000 with hand-washing--he or she is still likely to touch a piece of equipment that someone with dirty hands has touched."

Hospital officials said no evidence of the bacterium was found outside the NICU. Since the unit was closed Aug. 29, the ward's ceiling tiles have been taken down, faucets have been removed and air ducts have been cleaned and inspected to try to eliminate any reservoir where the bacteria could live, officials said.

Still, O'Rourke cautioned, "Human biology and microbial biology come together in the intensive care unit. There is no way to operate a sterile intensive care unit. The environment can be spotless. But we are also talking about the biological material in the unit--the human beings and the microbes."

In such a setting, "you don't have to postulate poor hand-washing or poor hygiene," O'Rourke emphasized. "You just have to understand the workings of an ICU to see how many opportunities there are to have that kind of interaction." Hospital officials confirmed that the organism was found on several workers' hands during testing.

Nosocomial, or hospital-acquired infections such as the cluster of P. aeruginosa fatalities at Children's, are "an unfortunate but constant fact of life at all hospitals," O'Rourke said. About 2 million nosocomial infections occur annually in U.S. hospitals, accounting for about 60,000 deaths. The recent deaths at Children's were unusual because they occurred as a cluster, because they appeared in a high-profile institution and because they affected a high-profile group of patients.

A spokesman for the Centers for Disease Control and Prevention in Atlanta said a different strain of P. aeruginosa killed three babies and infected five other infants in Detroit last spring.

O'Rourke said Children's has launched a major review of practices, in part to examine "issues in the environment to make sure something hasn't gone awry that nobody was aware of." But the human connection remains crucial, especially where hand-washing is concerned, O'Rourke said.

In terms of infection control, "hand-washing is still the No. 1, without question, weak point in every hospital in the world." Even at an institution of the caliber of Children's, "we don't come close to 100% on this issue," he said. "Anybody in any hospital will tell you that it is important, but as human beings we don't meet that criteria."

Hospital officials said NICU patients had been sent to other regional medical centers pending the unit's expected reopening this week.

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