Chris Miller, PHD
A needlestick exposure with blood from an HIV-positive person carries a risk of infection of less than 0.3 percent. For hepatitis B, this risk jumps to 6 to 30 percent. The difference in these risks is at least partially related to the level of the virus present in the blood of infected persons with HBV reaching much higher blood levels those infected with HIV. Unfortunately, we do not know the quantitative risk of infection for very many microbes, but we do know that contamination must occur before an infection can develop. So, let`s assess the risk of infection qualitatively. We`ll do this by discussing what likely would happen if contamination is allowed to occur because infection control procedures are not performed.
Wash hands before gloving
If hands are not washed before gloving, a higher level of skin microbes (mainly bacteria) will be present when gloves are put on for patient care. Since bacteria multiply beneath the gloves, more may be present to irritate the skin, to leak out should the gloves be torn or to contaminate a cut or puncture. If hands are not washed after removing gloves, a higher level of skin bacteria will remain, as will any microbes that may have passed through cuts, tears or pinholes in the gloves. Also, the chemicals from the gloves will remain on the skin in the absence of handwashing, possibly increasing chances of allergic sensitization or direct skin irritation.
Washing hands at other times also is important. Hands pick up transient microbes from all surfaces touched, and transfer them to other surfaces that are touched. As discussed in earlier columns, hands are the most important modes for spreading a variety of diseases. One is the common cold, because hands pick up viruses from the nose, mouth and facial tissues containing mucous and spread them to other surfaces which, in turn, are touched by others.
It is not only important to wash hands, but also to rinse them well. The lathering suspends or dissolves particles or chemicals and rinsing removes them. The chemicals in handwashing formulations also may be irritating to some people, if contact is prolonged by inadequate rinsing.
Why barriers are essential
Not using gloves, masks, protective eyewear and protective clothing during procedures is not wise. This is when contamination with the patient`s blood or saliva will most likely occur. Ungloved hands are susceptible to the entrance of microbes through invisible breaks in the skin, particularly around the fingernails. It`s better to prevent contamination by wearing gloves than to give the microbes a chance to enter invisible cuts. It`s also better to prevent microbes from contacting the hands than to risk not removing some of them after contamination. Although transient microbes usually are easily removed by handwashing, some may remain, particularly in hard-to-clean areas. This includes those resulting from any dermatitis. Studies have shown that trace amounts of blood can remain under the fingernails of a dentist for days, even with handwashing.
Preventing microbes - particularly human herpes virus Type 1 (HHV-1: herpes simplex virus) and hepatitis B virus - from contaminating the eyes is very important. Hepatitis B has been shown to be transmitted through contamination of the eye in chimpanzees, and this is assumed to be possible for humans. Almost every adult is infected with HHV-1, but only about 10 percent or so has recurring herpes lesions (fever blisters, herpes labialis). However, about 3-5 percent of adults actually shed low levels of the virus in saliva in the absence of lesions. Thus, the saliva from some unknown number of patients will contain HHV-1, and neither you nor they will know it.
Not using a mask when aerosols and spatter are being generated will permit the patient`s microbes to contact exposed skin and clothing. The skin itself is a very good barrier, but breaks can occur that may permit microbes to enter the body. Thus, as mentioned earlier, it`s probably best to prevent contamination in the first place.
Although there is no evidence that contaminated clothing in dentistry has even been involved in the spread of disease, it is obvious that the clothing worn at chairside does become contaminated. It`s simply poor hygiene to wear contaminated clothing home, putting loved ones at risk of exposure. You also should not wear it anywhere food may be eaten inside or out of the office. Thus, the best prevention is to wear protective clothing to eliminate the possibility of contamination of our skin and our work and street clothes, and then to properly manage the protective clothing.
Surface asepsis
Covered operatory surfaces are not susceptible to contamination, so they do not have to be cleaned and disinfected. They simply have to be recovered with fresh barriers for each patient. If uncovered surfaces become contaminated and are not cleaned and disinfected before being used with the next patient, that contamination may be spread to the next patient or to unprotected staff. Even though we have not documented cases of disease spreading from contaminated environmental surfaces in dentistry, it`s obvious that, at the very least, cross-contamination can occur.
A frequently asked question is: Can the microbes survive long enough on the environmental surfaces to be able to cause an infection leading to disease after being transferred? Unfortunately, microbial survival rates in real-life situations are not known because critical variables (such as level of microbes present, degree of protection from saliva/blood protein coating and humidity) are not known. Thus, the best preventive approach is to assume that any surface contaminated with blood or saliva is coated with live microbes.
Instrument sterilization
If contaminated instruments are not properly cleaned and sterilized, microbes from one patient will be transmitted to another patient. The same thinking applies here as that described for survival of microbes on environmental surfaces. If the instruments become contaminated (e.g., contact blood, tissue, mucous membranes, saliva), we must assume that the contaminating microbes still are alive. As with surface disinfection, if Gaynes now is in the process of establishing a private practice in partnership with an addiction counselor. It would seem that given her own history, the probability that she?ll achieve whatever goals she sets for herself are high. She describes her life as an odyssey, one that continues to take her to new destinations. About education, she says, OMy educational accomplishments gave me the ability to have something that was my own. I needed the education to say, OHey, look at me!? That?s something too many people, especially women, still are waiting to be able to say.O
Judith E. Sulik, RDH, is a frequent contributor to RDH, based in Bridgeport, Conn. She just finished writing her second cookbook, No sink? No counters? No problem! Interested readers can inquire about the Oone-potO recipes featured in cookbook by contacting Finely Finished Press, 60 Acton Road, Bridgeport, CT 06606; the cookbook costs $7.95.
Chris Miller is director of Infection Control Research and Services and professor of oral biology at Indiana University.
