Concern about transmission of AIDS and other blood-borne diseases during medical and dental treatment was heightened recently when a study found that the human immunodeficiency virus (HIV) can survive in dental tools that are not heat-sterilized.
Scientists from the University of Georgia reported in the British medical journal The Lancet last November that they found traces of HIV, the virus that causes AIDS, in dental instruments cleaned with disinfectant. The tools had previously been used to treat a dental patient who had AIDS. The scientists recommended that dental instruments be heat-treated between patient uses to eliminate the risk of transmitting HIV and other blood-borne viruses from one patient to another.
FDA reached the same conclusion last September, two months before the University of Georgia study was published. In a letter to all dentists in the United States, the agency advised that "reusable dental handpieces and related instruments (such as air/water syringes and ultrasonic scalers) be heat sterilized between each patient use.... Chemical disinfection is not recommended."
Since 1990, when news reports first suggested that HIV could be transmitted from a health-care provider to a patient, federal agencies and medical and dental professional societies have endeavored to do two things: assure patients that the risk of becoming infected with HIV, or another blood-borne disease, while getting medical or dental treatment is extremely small, and introduce additional precautions into health-care practice to further reduce this very small risk.
Health-care providers are at greater risk of blood-borne infections from their patients than the other way around. The national Centers for Disease Control and Prevention, the federal agency responsible for monitoring and controlling infectious disease in the United States, has reported 28 proven cases of HIV transmission from patients to health-care workers since surveillance of occupationally acquired HIV began in 1981. In another 18 cases, such transmission was deemed possible but not proven.
Although HIV is the infection people fear most, the hepatitis B virus (HBV) is both more common and more easily transmitted. CDC estimates that about 250,000 Americans become infected with HBV every year. Among them are about 10,000 health-care workers, most of whom are infected because of an injury from a hypodermic needle, or other sharp object, in the workplace.
A safe and effective vaccine, approved by FDA in 1982, prevents HBV infection, but many health-care workers are not vaccinated, and about 250 of them die every year from complications of HBV acquired on the job. (See Hepatitis B: "Available Vaccine Safe but Underused" in the May 1990 FDA Consumer.)
However, since HBV blood testing was introduced in the early 1970s, CDC has reported only about 300 cases of transmission of the virus from a health-care worker to a patient.
"The message to patients is, 'You pose a much greater risk to the clinician than the clinician poses to you.' That is scientifically supportable," says Tom Arrowsmith-Lowe, D.D.S., who is AIDS coordinator and deputy director of the Office of Health Affairs in FDA's Center for Devices and Radiological Health (CDRH).
Measures that protect the clinician also protect the patient, adds Arrowsmith-Lowe. "If we reduce the risk of the clinician becoming infected, we also reduce the risk of the clinician transmitting an infection to anybody else."
HBV and HIV are spread primarily through blood and through sexual activity. An infected woman can also transmit the virus to her fetus or newborn baby before or during delivery, or through breast milk.
Mucous membranes -- the moist linings of the mouth, sinuses, and body cavities such as the abdominal tract -- are also a portal of entry for infection. A blood-borne infection may be transmitted by cross-contamination -- using an improperly sterilized or disinfected device to treat an uninfected patient after treating an infected one.
The most frequent cause of blood-borne infections in health-care settings is a "needlestick" -- an injury with a needle or other sharp device. No one knows for sure how many such injuries occur because they often go unreported.
"Estimates range in the neighborhood of 800,000 needlesticks a year happening to health-care workers," says Arrowsmith-Lowe.
Since 1987, CDC has recommended the use of "universal precautions" to prevent the spread of blood-borne infections in health-care settings (see "Universal Precautions"). However, studies have shown that, even when universal precautions are fully observed, they prevent only one out of three needlestick injuries because gloves and other barriers are not impervious to sharp objects.
That is a matter of great concern to FDA, says Arrowsmith-Lowe. The devices involved in needlestick injuries -- such as syringes and intravenous (IV) equipment -- are regulated by the agency.
"This is a public health problem related to the use of a regulated product. It's clear that more needs to be done than just say, 'Be careful.' The obvious next step is to start looking at some ways to eliminate the problem.
"For example, when is the use of a 'sharp' [a needle or other sharp instrument] essential? To penetrate the skin. Well, if that's not the intended use of the 'sharp', perhaps you shouldn't be using one."
FDA applied this principle in April 1992 when it issued a safety alert to hospitals, advising against the use of exposed hypodermic needles to connect two pieces of IV equipment, a practice known as "piggybacking." In one research study, this practice caused half of all the needlestick injuries at a university medical center.
The agency recommended that hospitals use devices with recessed needles, or no needles at all, to connect IV equipment. Such devices are among the more than 50 products with features designed to prevent needlestick injuries that have so far been cleared for marketing by FDA.
In addition to IV connectors, these devices include needle guards, sheathed syringes, needle-recapping products, blood-drawing devices, IV catheters, and needleless injection devices. Pilot studies conducted at 10 hospitals in New York state in 1990 and 1991 found that needlestick injuries declined in a range of from 75 to 94 percent in the hospitals using these preventive devices.
Preventive devices fall broadly into two categories: those providing "passive," or automatic, protection, and those with a safety mechanism that must be activated by the user. Several studies have found that devices providing passive protection are both more effective and more acceptable to health-care workers than those that require the user to activate the safety feature.
FDA Eyeing New Devices
While FDA is encouraging manufacturers to develop more devices designed to prevent needlesticks, the agency is also concerned that such products meet the same standards of patient safety and effectiveness as those already on the market.
"We need to ensure that in providing these safer devices we don't degrade quality of care for the patient," says Tim Ulatowski, associate director for general devices in CDRH's Office of Device Evaluation. "For example, a needleless IV connector is undoubtedly safer for the user, but it may also present an increased risk of infection to the patient."
For this reason, FDA can -- and frequently does -- order trials of new preventive devices in patient-care settings before clearing them for marketing.
Sharp devices designed with safety in mind may be significantly different in appearance from their traditional counterparts. According to Linda Chiarello of the New York state health department, some patients were taken aback when they saw a passive protective needle that was being used to give injections at a hospital participating in the state's pilot studies of safer sharp devices.
"This needle is about twice as long as a traditional needle because it has a protective housing that retracts as the needle is injected. Nurses, as well as patients, were intimidated by the sight of this needle because it was so much larger than an ordinary needle."
As both a regulatory and a public health agency, FDA has a strong interest in promoting the development of new technologies that protect both health-care workers and their patients from injury, says Arrowsmith-Lowe. Together with the Occupational Safety and Health Administration and CDC, FDA cosponsored a conference held in Washington, D.C., last August on preventing device-mediated blood-borne infections.
The purpose of the three-day meeting, which brought together scientists, government officials, device manufacturers, hospital administrators, and health-care workers, was to draw attention to the toll taken by needlestick injuries and encourage the adoption of safer sharps technology.
"There is a revolution in device design going on," says Arrowsmith-Lowe, "and I'm confident the result will be a significant reduction in the risk faced by clinicians -- as well as by patients -- of contracting blood-borne infections in the health-care setting."
Preventing the spread of blood-borne infections among health-care workers and their patients means preventing exposure to infected blood or body fluids, coupled with strict sterilization and disinfection procedures for reusable devices.
Using precautions when caring for known infected individuals isn't enough, because people can carry HBV or HIV infection without being aware of it or showing symptoms.
Since 1987, therefore, the national Centers for Disease Control and Prevention, the federal agency responsible for monitoring and controlling infectious disease in the United States, has recommended the use of "universal precautions" to prevent the spread of HBV, HIV, and other blood-borne infections in health-care settings.
The basis of universal precautions is the assumption that blood and body fluids of all patients may be infectious, and that measures to protect against exposure must be observed at all times. FDA officials cooperated with CDC in the development of these precautions.
The major elements of universal precautions are:
Use of "protective barriers" -- gloves, gowns, goggles, and face masks -- when appropriate to reduce the risk of exposure to blood and other potentially infectious body fluids. For example, dentists should wear face masks when working in a patient's mouth. Between patients, hands should be washed, and gloves and other barriers changed.
Caution in handling needles, scalpels, and other sharp instruments. Needles should not be recapped, removed from disposable syringes, bent, broken, or otherwise manipulated by hand.
Disposal of needles and other sharp instruments in specially labeled, puncture-resistant containers located as close as is practical to the area where the "sharps" are used.
Use of gloves to draw blood when a health-care worker has skin cuts or scratches, when drawing blood from a child, when an inexperienced person is being trained to draw blood, or in any other situation in which hand contamination with blood might occur.
Immediate and thorough washing of hands or other parts of the body contaminated with blood or other potentially infectious body fluids.
CDC has also set guidelines for disposing of infected trash and for sterilization and disinfection of reusable equipment in hospitals and other health-care settings.
Nondisposable instruments that penetrate the skin, such as nondisposable needles and scalpels, must be sterilized before each use. In addition, FDA now recommends that dental instruments such as drills and air syringes be heat-sterilized before each use (see above). Effective methods of sterilization are dry heat ovens and autoclaves. An autoclave is a device similar to a pressure cooker that uses steam to sterilize.
Gas and chemical vapor sterilizers are also cleared by FDA for sterilizing certain dental devices. In any case, the dental device must be compatible with the selected method of sterilization, and the sterilizer must be used according to its labeling.
Devices that do not penetrate the skin or come in contact with normally sterile areas of the body, such as several types of endoscopes, must be disinfected, at a minimum, with an EPA-registered and FDA-cleared disinfectant. The disinfectant selected must be of appropriate strength to kill the types of organisms that may contaminate the particular device.
Universal precautions have been endorsed by all the major health-care professional societies, including the American Medical Association, the American Dental Association, and the American Nurses Association. In 1991, Congress passed a law requiring states to adopt the CDC guidelines or their equivalent.
Most recently, the federal Occupational Safety and Health Administration has incorporated universal precautions into a new standard on occupational exposure to blood-borne pathogens, which became effective in March 1992.
The OSHA standard requires all employers to protect workers who risk exposure to blood and other potentially infectious body fluids on the job. The standard applies to hospitals, medical and dental offices, laboratories, and any other workplace where exposure to infected blood might occur. Employers found in violation of the standard may be fined up to $70,000.
The new standard also requires employers to offer free HBV vaccine to at-risk workers. The cost of the vaccination was one factor that previously deterred many workers from taking advantage of this preventive measure.
Ask Your Dentist
FDA and other federal agencies agree with the American Dental Association (ADA) that the risk of acquiring HIV during dental treatment is extremely remote.
The ADA supports the use of universal precautions (see "Universal Precautions") and suggests that consumers look for -- and ask their dentists whether they are following -- these infection control procedures:
Dentist and staff wear gloves and a mask during all patient treatment.
Dentist and staff wash their hands before and after each patient and change gloves after each patient.
Dental instruments are cleaned and sterilized after each use.
Surfaces and equipment in the treatment room are cleaned and disinfected after each patient.
Needles and other sharp items are disposed of in special containers.
All dentists should be heat-sterilizing instruments such as drills, air and water syringes, and scalers after each patient use, as a result of an FDA recommendation last September.