Approach to Disinfection and Sterilization

Disinfection and sterilization are important of the guaranteeing that medical and surgical instruments do not transmit infectious pathogens between patients. “Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008”, written by William A. Rutala, David J. Weber and the Healthcare Infection Control Practices Advisory Committee (HICPAC), has presents a proper use of disinfection and sterilization process. The approach is based on well-designed studies assessing the efficacy and effectiveness of disinfection and sterilization procedures.

There are different terms use in disinfection and sterilization, and each stands for different purpose.

Cleaning is removing the visible soil from objects and surfaces and normally is accomplished manually or mechanically using water with detergents or enzymatic products. Careful cleaning is necessary before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments intervene with the effectiveness of these processes.

Disinfection is a process that eliminates most or all-pathogenic microorganisms, except bacterial spores, on non-living objects. In health-care settings, instruments usually are disinfected by liquid chemicals or wet pasteurization. There are several factors that affect the efficacy of both disinfection and sterilization include prior cleaning of the object; amount of organic and inorganic present; type and level of microbial contamination; concentration of and exposure time to the germicide; physical nature of the object; presence of biofilms; temperature and pH of the disinfection process; and in some case, relative humidity of the sterilization process.Although disinfection is not sporicidal, chemical sterilants will kill spores with prolonged exposure times (3 - 12 hours).

Sterilization is a process that destroys or eliminates all forms of microbial life. In health-care installations usually perform by physical or chemical methods. The principal sterilizing agents used in health-care facilities are steam under pressure, dry heat, ETO gas, hydrogen peroxide gas plasma, and liquid chemicals.

Germicide is an agent that can kill microorganisms, particularly pathogenic organisms. The term germicide includes both antiseptics and disinfectants. 

Antiseptics are germicides applied on living tissue and skin. 

Disinfectants are antimicrobials applied only to non-living object. Normally, disinfectants cannot be used for skin antisepsis because they can injure skin and other tissues.

Spaulding categorized the instruments and items for patient care into critical, semicritical, and noncritical according to the degree of risk for infection involved in use of the items. Critical items have high potential for infection if they are contaminated with any microorganism. Critical items must be sterile because these items enter sterile tissue or the vascular system that microbial contamination could transmit disease. Critical items should be purchased in sterile or be sterilize with steam. Semicritical items contact mucous membranes or non intact skin. These medical devices should be free from all microorganisms. Since intact mucous membranes, such as lungs and the gastrointestinal tract, generally are resistant to infection by common bacterial spores, small numbers of bacterial spores are permissible. Semicritical items minimally require high-level disinfection using chemical disinfectants. Noncritical items get into contact with nonintact skin for a brief period of time. Thee items should be disinfected with intermediate-level disinfectants, such as phenolic, iodophor, alcohol, or chlorine.

Dental instruments as possible agents for pathogen transmission, the American Dental Association recommends that surgical and other instruments that normally get across soft tissue or bone be classified as critical device that should be sterilized after each use or discarded. Handpieces can be contaminated with patient material and should be heat sterilized after each patient. For heat-stable crtitical or semicritical dental instruments and materials can sterilize by steam under pressure (autoclave), chemical vapor (formaldehyde), or dry heat (320 °F for 2 hours).

 

Centers for Disease Control (CDC) has divided noncritical surfaces in dental offices into clinical contact and housekeeping surfaces. Clinical contact surfaces are surfaces that be touched with gloved hands during clinic or that become contaminated with blood or other infectious material and subsequently contact items, such as light handle, switches, dental X-ray equipment, and chair-side computers.  For these surfaces especially surfaces that are difficult to clean, barrier protective coverings can be used. The coverings should be changed when damaged and routinely. If the surface is not barrier-protected, these surfaces should be disinfected between patients with an intermediate-disinfectant. On the other hand, housekeeping surfaces need to be cleaned only with a detergent and water or an Environmental Protection Agency (EPA)-registered hospital disinfectant.

Similar with antibiotics, reduced susceptibility of bacteria to disinfectants can arise by with chromosomal gene mutation or acquisition of genetic material. Nevertheless, reduced susceptibility to disinfectants does not associate with failure of the disinfectant since concentrations used in disinfection still greatly exceed the cidal level. Nowadays, evidence and reviews indicated enhanced tolerance to disinfectants could be developed in response to disinfectant exposure. However, the level of tolerance is low and unable to compromise the effectiveness of high concentration disinfectants. In addition, the rotational use of disinfectants in pharmacy production units has been recommended and practiced in an attempt to prevent development of resistant microbes.

The effective use of disinfectants is part of a multibarrier strategy to prevent health-care-associated infections. Although use of noncritical items or contact with noncritical surfaces carries little risk of causing an infection in patients or staff, medical equipment surfaces can become contaminated with infectious agents and contribute to the spread of health-care-associated infections. For this reason, noncritical medical equipment surfaces should be disinfected with an EPA-registered low- or intermediate-level disinfectant.

Even more, there are five reasons to use a disinfectant on noncritical surfaces, which particularly support the use of a germicidal detergent.

1.     Hospital floors become contaminated with microorganism from settling airborne bacteria. The removal of microbes is a factor of controlling health-care-associated infections. The use of phenolic disinfectant has higher effective in reducing the numbers of bacteria than the use of soap and water.

2.     Soap and water detergents without disinfectants become contaminated and result in spread bacteria to patient’s environment.

3.     CDC Isolation Guideline recommends that noncritical equipment contaminated with blood, body fluid, secretions, or excretions be cleaned and disinfected after use. It also recommends that to cleaning, disinfection of the bedside equipment and environmental surface for certain pathogens, which can survive in the non-living environment for prolonged periods.

4.     Occupational Safety and Health Administration (OSHA) requires that surfaces contaminated with blood and other potentially infections materials be disinfected.

5.     Using a single product throughout the installation can simplify both training and appropriate practice.