DALLAS, June 11 — Tiny red pharaoh ants have invaded operating rooms, intensive care units and nurseries in some Texas hospitals, posing a ‘’significant risk” to patients by feeding in open wounds, university researchers say.

”They have been found in all parts of the hospitals,” said Harry Howell, a research associate at Texas A&M University, which released a study on the ants Thursday. ”In some hospitals, we found them in surgery rooms. At Brooke Army Medical Center, we found the whole hospital was infested.”

The study said that about one-fourth of 57 hospitals surveyed were infested with the ants. Entomologists in the A&M Urban Integrated Pest Management Project said that the ants, a household pest in most of the world, were found to carry staphylococcus bacteria and other disease-causing organisms.

”For the debilitated patient, they pose a significant risk,” said Dr. David McMurray, a professor of microbiology and immunology. Findings Held Premature

The findings were disputed by Dr. Karl Shaner, vice president of research and development for the Texas Hospital Association, which cooperated with the study. He said that the limited survey, which covered less than 10 percent of the state’s 590 hospitals, had produced inconclusive evidence.

”My concern is that any inference that large numbers of hospitals have this problem and that it is highly contagious is premature,” Dr. Shaner said.

The survey, begun in April, turned up ants in intravenous tubes and glucose solutions. Mr. Howell said three ants were recovered from an opening in a patient’s neck.

”The most common thing like that was where you had a large open wound like a burn,” he said. ”The ants come to feed on the burn site and on the burn ointments.

”I would think that from some of the things we observe from the ants, that they have potentially more of a health hazard than cockroaches,” he added. ”We perceive them to be a problem in all health institutions.” Burn Center Problem Cited

He said the ”biggest problem” was at Brooke, which has a worldfamous unit that specializes in treating serious burns. Mr. Howell said that Brooke ”had burn patients whose wounds were infested and ants in cribs in the nursery.”

However, Brooke was able to get the ants out of its patient care area, and they remain only in a few administrative offices, Mr. Howell said.

A spokesman for the San Antonio facility, Ray Dery, said he was unaware of the study’s results, but knew that ”in the past we’ve had problems with ants – not problems that went unresolved.”

Mr. Howell said he could not identify other infested hospitals because the hospital association had requested anonymity for its members. But he said that all the hospitals had taken steps to get rid of the ants.

Officials at Brooke tried a residual insecticide spray, but it tends to act as a repellant so the ants do not cross it. Brooke then used a poison bait that has a low human toxicity so it could be placed around the hospital. The ants feed on it, then go back to the colony to feed the immature ants. Over a period of weeks the colony is killed off. Pest Control Efforts

Some pest control operators are doing this in other hospitals, but it is a tedious process, Mr. Howell said. Some just prefer to spray any ants they see.

Researchers are trying to determine if there is any link between the ants and hospital-acquired infections. Pharaoh ants in Europe were discovered to be carriers of bacteria and were also linked with the spread of swine pneumonia in a veterinary research facility.

”The fact that we find the bugs with the ants may be circumstantial evidence,” said Dr. David McMurray, a professor of microbiology and immunology. ”The real link has yet to be proven.”

Microbiologists in the A&M College of Medicine are trying to develop chemical baits to control the ants.

Lee Ann Torrans
ltorrans@gmail.com