Copyright © 2005 by Elsevier Inc. All rights reserved. Principles and Techniques of Disinfection Chapter 20

Copyright © 2005 by Elsevier Inc. All rights reserved. Introduction During patient treatment, the equipment and treatment room surfaces are likely to become contaminated with saliva or by aerosol containing blood and/or saliva. Laboratory studies have determined that microorganisms may survive on environmental surfaces for different periods of time. Assume that if the surface has had contact with saliva, blood, or other potentially infectious materials, it contains live microorganisms.

Copyright © 2005 by Elsevier Inc. All rights reserved. Environmental Infection Control The CDC Guidelines for Infection Control in Dental Health-Care Settings 2003 have divided environmental surfaces into clinical contact surfaces and housekeeping surfaces. Housekeeping surfaces include floors, walls, and sinks. Because these have much lower risk for disease transmission, the cleaning and decontamination is not as rigorous as those used for clinical areas and for patient treatment items.

Copyright © 2005 by Elsevier Inc. All rights reserved. Things to Consider When Cleaning and Disinfecting Patient Treatment Areas Amount of direct patient contact Type and frequency of hand contact Potential amount of contamination by aerosol and spray Other sources of microorganisms (e.g., dust, soil, or water)

Copyright © 2005 by Elsevier Inc. All rights reserved. Clinical Contact Surfaces Clinical contact surfaces can be directly contaminated either by direct spray or spatter generated during dental procedures, or by contact with the dental professional’s gloved hands. Current infection control guidelines of the Office Safety and Asepsis Procedures Research Foundation (OSAP) recommend that clinical surfaces be classified and maintained under three categories: –(1) touch –(2) transfer –(3) splash, spatter, and droplet

Copyright © 2005 by Elsevier Inc. All rights reserved. Types of Clinical Contact Surfaces Touch surfaces are directly touched and contaminated during treatment procedures. Touch surfaces include dental light handles, dental unit controls, chair switches, chairside computers, pens, telephones, containers of dental materials, and drawer handles. Transfer surfaces are not directly touched but often are touched by contaminated instruments. Transfer surfaces include instrument trays and handpiece holders. Splash, spatter, and droplet surfaces do not actually contact the members of the dental team or the contaminated instruments or supplies. Countertops are a major example.

Copyright © 2005 by Elsevier Inc. All rights reserved. Managing Surface Contamination There are two methods to deal with surface contamination: –Barriers –Preclean and disinfect surfaces between patients

Copyright © 2005 by Elsevier Inc. All rights reserved. Types of Surface Barriers There is a wide variety of surface barriers available on the market today. All should be resistant to fluids to keep microorganisms in saliva, blood, or other liquids from soaking through to contact the surface underneath. Some plastic bags are designed especially to the shape of items such as the dental chair, air-water syringe, hoses, pens, light handles, etc. Plastic-barrier sticky tape is frequently used to protect smooth surfaces such as touch pads on equipment, electrical switches on chairs, or x-ray equipment. Aluminum foil can also be used because it is easily formed around any shape.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig An example of water on a fluid-resistant material (Courtesy Crosstex.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Surfaces touched during patient care should be covered by protective barriers. If not protected, they must be cleaned and disinfected at the end of the procedure.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Rolls of plastic tubing that can be cut to the desired length (Courtesy Certol.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Tube socks provide barrier protection for difficult to clean areas. (Courtesy Certol.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Remember, if a surface cannot be easily and thoroughly cleaned and disinfected, it should have barrier protection.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig A, Touch surfaces. B, Transfer surfaces. C, Splash, spatter, and droplet surfaces.

Copyright © 2005 by Elsevier Inc. All rights reserved. CDC Guidelines If barriers are not used, surfaces should be cleaned and disinfected between patients by using and EPA- registered hospital disinfectant with an HIV, HBV claim. Use PPE, as appropriate, when cleaning and disinfecting environmental surfaces. Such equipment might include: –Gloves (e.g., puncture- and chemical-resistant utility) –Protective clothing –Protective eyewear/face shield and mask

Copyright © 2005 by Elsevier Inc. All rights reserved. Precleaning and Disinfection Precleaning means to clean before disinfecting. All contaminated surfaces must be precleaned before they can be disinfected. Even if there is no visible blood on the surface, it must be precleaned because even a thin layer of saliva on the surface can decrease the effectiveness of the disinfectant. Precleaning reduces the number of microbes and removes blood and saliva (also called bioburden).

Copyright © 2005 by Elsevier Inc. All rights reserved. Precleaning and Disinfection-cont’d These techniques are most effective when used on contaminated surfaces that are smooth and easily accessible for cleaning. Always wear your utility gloves, mask, protective eyewear, and protective clothing when precleaning and disinfecting. Surfaces that are irregular or textured are difficult or impossible to clean, therefore interfering with disinfection. Regular soap and water may be used for precleaning, but it is more efficient if you select a disinfectant that has the ability to clean as well as disinfect.

Copyright © 2005 by Elsevier Inc. All rights reserved. The assistant shown here places clean wrap barriers on the handles of the operating light (Figure from Procedure 20-1).

Copyright © 2005 by Elsevier Inc. All rights reserved. Disinfection Disinfection is intended to kill disease-producing microorganisms that remain on the surface after precleaning. Spores are not killed during disinfecting procedures. Do not confuse disinfection with sterilization. Sterilization is a process in which all forms of life are destroyed.

Copyright © 2005 by Elsevier Inc. All rights reserved. Disinfectants Versus Antiseptics Disinfectants are chemicals that are applied to inanimate surfaces (such as countertops and dental equipment). Antiseptics are antimicrobial agents that are applied to living tissue. Disinfectants and antiseptics should never be used interchangeably because tissue toxicity and damage to equipment can result.

Copyright © 2005 by Elsevier Inc. All rights reserved. Disinfectants Disinfectants are chemicals that destroy or inactivate most species of pathogenic (disease-causing) microorganisms. In dentistry, only those products that are Environmental Protection Agency (EPA)-registered hospital disinfectants with tuberculocidal claims (kills the tuberculosis bacteria) should be used to disinfect dental treatment areas. Mycobacterium tuberculosis is highly resistant to disinfectants, and if a disinfectant will inactivate M. tuberculosis, it will most certainly inactivate the less resistant microbial families (such as bacteria, viruses, and most fungi) on the treated surface.

Copyright © 2005 by Elsevier Inc. All rights reserved. The Perfect Disinfectant? If there were an ideal surface disinfectant, it would have a rapid kill of a broad spectrum of bacteria, have residual activity, minimal toxicity, and would not damage surfaces to be treated. In addition, it would be odorless, inexpensive, work on surfaces with remaining bioburden, and be simple to use. Unfortunately, no single disinfectant product on the market today meets all these criteria. When selecting a surface disinfectant, you must carefully consider the advantages and disadvantages of various products. Often the manufacturers of dental equipment will recommend the type of surface disinfectant that is most appropriate for their dental chairs and units.

Copyright © 2005 by Elsevier Inc. All rights reserved. Table 20-2 EPA-Registered Surface Disinfectants for Dentistry

Copyright © 2005 by Elsevier Inc. All rights reserved. Types of Chemical Surface Disinfectants Iodophors are EPA-registered intermediate-level hospital disinfectants with tuberculocidal action. –Because iodophors contain iodine, they may corrode or discolor certain metals and may temporarily cause reddish or yellow stains on clothing and other surfaces. Synthetic phenol compounds are EPA-registered intermediate-level hospital disinfectants with broad- spectrum disinfecting action. –Phenols can be used on metal, glass, rubber, or plastic. They also may be used as a holding solution for instruments; however, phenols leave a residual film on treated surfaces. Synthetic phenol compound is prepared daily.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Iodophor surface disinfectant (Courtesy Certol.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Synthetic phenol surface disinfectant (Courtesy Certol.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Types of Chemical Surface Disinfectants-cont’d Sodium hypochlorite (household bleach) is a fast-acting, economical, and broad-spectrum intermediate-level disinfectant (1:100 dilution for surface decontamination). –Disadvantages: Unstable, must be prepared daily, strong odor, corrosive to some metals, destructive to fabrics, and irritating to the eyes and skin; it may eventually cause plastic chair covers to crack. Alcohols are not effective in the presence of blood and saliva. They evaporate quickly and are damaging to certain materials such as plastics and vinyl. –The American Dental Association (ADA), CDC, and the Office of Safety and Asepsis Procedures Research Foundation (OSAP) do not recommend alcohol as an environmental surface disinfectant.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Sodium hypochlorite (household bleach) is a disinfectant, but is not EPA-registered and should not be used in dentistry as a surface disinfectant.

Copyright © 2005 by Elsevier Inc. All rights reserved. Immersion Disinfectants There are chemicals on the market that can be used for sterilization or high level disinfection. When used as a sterilant they destroy all microbial life, including bacterial endospores. Depending on the type, time for sterilization can range from 6 hours to 30 hours. At weaker dilutions or at shorter contact time, these chemicals provide high-level disinfection, which inactivates all microorganisms except endospores. Most of these chemicals are toxic and can irritate the eyes, skin, and lungs. PPE must always be worn when using these chemicals. They are to be used for immersion (soaking) of heat-sensitive instruments, and should never be used as surface disinfectants. Always keep the lid closed on containers to minimize the fumes.

Copyright © 2005 by Elsevier Inc. All rights reserved. Immersion Disinfectants Chlorine dioxide is an effective rapid-acting environmental surface disinfectant (3 minutes) or chemical sterilant (6 hours). Chlorine dioxide does not readily penetrate organic debris and must be used with a separate cleaner. Other disadvantages of chlorine dioxide are that it must be prepared fresh daily, it must be used with good ventilation, and it is corrosive to aluminum containers.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Covered instrument tray for use with immersion disinfectants (Courtesy Certol.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Glutaraldehyde Glutaraldehyde is classified as a high-level disinfectant/sterilant. It can also be used as a liquid sterilant when the immersion time is greatly increased. Glutaraldehyde products are useful for plastics or other items that cannot withstand heat sterilization. Glutaraldehyde is very toxic and should be handled carefully to avoid the fumes. Glutaraldehyde-treated instruments should never be used on patients without thoroughly rinsing them with water. Prolonged contact of certain types of instruments with glutaraldehyde solutions can lead to discoloration and corrosion of the instrument surfaces and cutting edges.

Copyright © 2005 by Elsevier Inc. All rights reserved. Ortho-phthala-dehyde (OPA)-Immersion Disinfectant Ortho-phthala-dehyde (OPA) is classified as a high-level disinfectant. It is effective in achieving high-level disinfection within 12 minutes at room temperature. It is more expensive than glutaraldehydes, but may be a good alternative for individuals with a sensitivity to glutaraldehydes. It has very little odor and does not require activation or mixing. Disadvantages include: (1) the cost, (2) it can be used only half as long as most glutaraldehydes in dentistry, (3) it may stain skin and fabrics, (4) plastics turn a blue-green color where proteins have not been removed, and (5) it would require over 30 hours to provide sterilization.

Copyright © 2005 by Elsevier Inc. All rights reserved. Fig Fast-acting, high-level disinfectant (Courtesy Crosstex.)

Copyright © 2005 by Elsevier Inc. All rights reserved. Housekeeping Surfaces There is no scientific evidence that shows that housekeeping surfaces (e.g., floors,walls, and sinks) pose a risk for disease transmission in dental healthcare settings. The majority of housekeeping surfaces need to be cleaned only with a detergent and water or an EPA-registered hospital disinfectant/detergent. However, in the cleaning process, a reservoir for microorganisms can be used solutions of detergents or disinfectants, especially if prepared in dirty containers, stored for long periods of time, or prepared incorrectly. Make fresh cleaning solution each day, and discard any remaining solution, and let the container dry. This will minimize bacterial contamination. When cleaning, try to avoid producing mists and aerosols or dispersing dust in patient-care areas.

Copyright © 2005 by Elsevier Inc. All rights reserved. Carpeting and Cloth Furnishings Carpeting is more difficult to clean than nonporous hard surface flooring, and it cannot be reliably disinfected, especially after contamination with blood and body substances. Studies have documented the presence of bacteria and fungi in carpeting. Cloth furnishings pose similar contamination risks in areas where there is direct patient care and where contaminated materials are handled, such as an operatory or instrument processing area. CDC Guidelines: Avoid using carpeting and cloth-upholstered furnishings in dental operatories, laboratories, and instrument processing areas.

Copyright © 2005 by Elsevier Inc. All rights reserved. Spills of Blood and Body Substances The majority of blood contamination in dentistry results from spatter and rotary or ultrasonic instruments. No scientific evidence shows that HIV, HBV, or HCV have been transmitted from a housekeeping surface. OSHA requires that blood spills and other body fluids be removed and the surfaces disinfected. Always wear gloves and other PPE when decontaminating areas of spills. CDC Guidelines: Clean spills of blood or other potentially infectious materials and decontaminate surface with an EPA- registered hospital disinfectant with low- (i.e., HBV and HIV label claims) to intermediate-level (i.e., tuberculocidal claims) activity, depending on the size of the spill and surface porosity.