A chemical disinfectant used on some medical and dental devices can fail to kill the AIDS virus, posing a potential risk of infecting patients, a study suggests.
Researchers found that in the laboratory, the disinfectant did not kill the AIDS virus in blood lodged in lubricants commonly used in dental equipment and in medical devices called endoscopes, which are inserted into the body to allow an interior view.
None of the devices has ever been shown to be the cause of HIV transmission from patient to patient, said researcher David Lewis, a microbiologist at the University of Georgia in Athens.
In the study, published by Lewis and another researcher in the September issue of the journal Nature Medicine, the AIDS virus survived after the contaminated lubricants were soaked for two hours in a powerful germ-killer called glutaraldehyde.
Lewis said the study emphasizes the need to sterilize dental equipment at extremely high temperatures, as recommended by the federal government and the American Dental Association.
He also said the standards for decontaminating endoscopes should be raised.
Lewis believes the finding may help explain the mystery of Florida dentist David Acer, who infected a half-dozen patients in the late 1980s, as well as unknown numbers of other AIDS cases in which investigators have found no other risk factor.
Among the 441,528 cases of AIDS in this country reported so far by the U.S. Centers for Disease Control and Prevention, 3 to 6 percent, or as many as 26,280 cases, fall into this category.
One such case, that of a 48-year-old Northampton, Mass., man, may come before a jury in the next few months. James Sharpe and his wife, Jeanne, former convenience store owners, said in an interview Tuesday they are convinced a Springfield, Mass., dentist transmitted the human immunodeficiency virus through contaminated equipment in late 1989, when Sharpe had three teeth extracted.
James Sharpe, who now has full-blown AIDS, said he would advise all dental patients to ask dentists if they autoclave, or heat-sterilize, their instruments before each use. “It is your right, as John Q. Patient, to say, ‘Are you autoclaving?’ and ‘Prove it.”’
The American Dental Association agrees with Sharpe’s advice. But its statistics indicate that only one patient in 20 does ask about infection control.
The issues regarding contamination of medical endoscopes, which are used to diagnose and treat gastrointestinal and respiratory disease, are different from those involving dental instruments.
“Probably 80 percent of the endoscopes used in the U.S. get sterilized with 2 percent glutaraldehyde between patients,” said Lewis.
The American Dental Association Tuesday said 92.3 percent of U.S. dentists surveyed last month claim to heat-sterilize hand instruments before each use. If that is accurate, it suggests that about 12,000 U.S. dentists do not routinely sterilize such tools as recommended.
Lewis estimates that 40 to 80 percent of dentists actually autoclave their instruments.