Handwashing plays simple, but vital, role in reducing microbial contamination

April 1, 1997
In the March 1997 RDH, we examined aseptic techniques that prevent the additional spread of microbes. The Infection Control column discussed the techniques in regard to the donning and removing of personal protective barriers and managing the contamination of operatory surfaces.

Chris Miller, PHD

In the March 1997 RDH, we examined aseptic techniques that prevent the additional spread of microbes. The Infection Control column discussed the techniques in regard to the donning and removing of personal protective barriers and managing the contamination of operatory surfaces.

This month, we will review the aseptic techniques of handwashing and instrument processing.

Clean hands make a difference

Handwashing is probably the most important aseptic technique involved in preventing the spread of many disease agents. The hands contact a variety of surfaces throughout the day. In doing so, they become contaminated with microbes from those surfaces. The contaminating microbes acquired by the hands can usually be easily removed by routine handwashing and do not colonize the skin. This is why they are referred to as the transient flora (non-permanent members of the skin flora).

The resident flora of the skin consist of microbes that actually colonize the skin and stay on the hands permanently. These microbes are not easily removed by routine handwashing or even by surgical scrubbing procedures (although the latter can reduce their number).

The transient flora, in contrast to the resident flora, is by far the most important flora involved in the spread of disease. The resident flora may be involved in causing harmful infections if deposited in open tissue or other body sites that are normally sterile.

The hands may play a role in the spread of gastrointestinal, eye, and skin diseases. But they are of paramount importance in the spread of most respiratory diseases. This is true not only in the health care environment, but also in our homes.

In the home, unprotected coughing and sneezing can contaminate surfaces several feet away that then may be touched by family members. The family members may subsequently touch their own noses, mouths, and eyes which allows entry of the contaminating microbes. In addition, someone with a respiratory disease commonly contaminates their own hands by:

- Covering their mouth and nose when sneezing or coughing.

- Contacting moisture from their eyes when rubbing them.

- Handling facial tissue when "blowing" their nose.

- Touching their nose or mouth.

When surfaces are touched by those contaminated hands and then touched by family members, the spread of disease can occur. How can you reduce the spread of respiratory microbes to others in the home? If you have a cough, "runny" nose, watery eyes, or sore throat, wash your hands more frequently, particularly after they have become obviously contaminated, and use a separate hand towel from the rest of the family. Stay out of the kitchen, and don`t handle food or drink for others. Cover your mouth and nose when sneezing or coughing, and immediately discard used facial tissues in a trash container rather than placing them on a table, the arm of a chair, or leaving them for someone else to pick up.

Other family members should wash their hands more frequently as well. As a general rule, we all should try to reduce rubbing our eyes or touching our faces with unwashed hands.

Tips for handwashing in the office

The preventive approaches described above also apply to the dental office. Hands are washed before gloving to reduce the level of skin flora. If this is done, there will be fewer microbes to multiply beneath the gloves and irritate the skin. This also helps reduce the number of microbes that may contaminate your patient if, indeed, your gloves tear during intraoral care.

Hands are washed after discarding gloves to remove those transient microbes that may have been acquired through unrecognized tears or pinholes in the gloves and to reduce the microbes that multiplied on the skin beneath the gloves.

The purpose of routine handwashing is to remove dirt and the transient microbes. Remove rings at the beginning of the day before handwashing. Jewelry, as well as long fingernails, may serve as additional hiding sites for bacteria, and they also may make donning gloves more difficult or tear gloves. The use of artificial nails and even nail polish also may discourage vigorous handwashing.

An antimicrobial handwashing agent (containing chlorhexidine gluconate, para-chlora-meta-xylanol, or triclosan, for example) should be used. Vigorously lather the hands for 10 to 15 seconds. Don`t avoid the fingernail areas or backs of the hands and fingers. A soft brush may be used for the first handwashing of the day, but take care not to be so vigorous in scrubbing or cleaning your fingernails that you break the skin.

Rinse the hands thoroughly under cool or lukewarm running water. Pat dry (rather than rub) with clean paper towels. If hand lotions are used as a moisturizer, switch to water-based lotions. Petroleum-based lotions may tend to compromise latex glove integrity.

The purpose of the surgical hand scrub is to remove dirt and the transient microbes, as well as reduce the level of the resident microbes. Surgical scrubbing involves multiple scrubbing and rinsing for two to five minutes with an antimicrobial surgical scrub (chlorhexidine gluconate or iodophor surgical scrub, for example) and a soft brush or sponge. This is followed by a final rinsing with the hands held above the level of the elbows until they are dried with sterile towels.

Since even this procedure will not remove all of the resident flora, sterile gloves are donned before the surgery.

Instrument Processing

The aseptic techniques involved with instrument processing mainly involve the proper handling of instruments after they have been sterilized and before they are used on another patient. The most important aseptic technique is to package the instruments in pouches, packs, or wrapped cassettes prior to placing them in the sterilizer. By doing this, they will be protected from re-contamination after they are removed from the sterilizer.

Unpackaged instruments are susceptible to re-contamination immediately upon removal from the sterilizer, usually from dust in the air, dental aerosols, surfaces, and contaminated hands/gloves. However, packaging will protect the instruments only as long as it remains dry and intact. So it is important to allow packages to dry before they are removed from a steam sterilizer. Packages are already dry at the end of cycles in a dry heat sterilizer or in a Chemiclave.

Wet packages attract microbe-laden dust from the air, and the microbes may then penetrate through the wet material to the instruments inside. Also, wet packages tend to easily tear when handled. Sterile packages should be handled as little as possible and stored in a clean, dry, cool, low-dust area until distributed at chairside for use.

Sterilizer cycles with shortened exposure times (sometimes referred to as OflashO sterilization) require that the processed instruments be unpackaged. Since this eliminates the protection normally given by the packaging material, such cycles should be performed only when an emergency situation occurs so that aseptic technique is not routinely sacrificed. Whenever these short-time OunwrappedO cycles are performed, a carefully designed protocol should be in place and strictly followed to protect those instruments from re-contamination, as much as possible, before they are used on another patient.

Proper handwashing and maintaining the integrity of packaged sterile instruments are very important aseptic techniques that can reduce the spread of disease agents in the office.

Chris Miller is director of Infection Control Research and Services and professor of oral biology at Indiana University.