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How to Properly Disinfect Reusable Surgical Instruments Part I

Disinfection is the process designed to eliminate all pathogenic microorganisms from reusable surgical instruments prior to sterilization. In most instances, reusable surgical instruments and medical devices are disinfected by the use of approved liquid chemicals or by wet pasteurization. There are numerous variables that can affect the efficacy of the disinfection process. Some of these variables can limit, or even nullify, the efficacy of the disinfection of the reusable surgical instruments.

As described in an earlier Elmed blog (“How to Properly Clean Surgical Instruments”) cleaning is the removal of visible soil (e.g., organic and inorganic material) from surgical instruments and reusable medical devices. This is normally accomplished manually or mechanically using water with detergents or enzymatic products with a neutral pH (7 or lower).

Thorough cleaning is essential before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of surgical instruments interfere with the effectiveness of these processes. Decontamination removes pathogenic microorganisms from reusable surgical instruments and medical devices so that they are safe to handle, use, or be sent out for maintenance or repair.

There are numerous factors that can affect the efficacy of the disinfection process. According to the CDC, these factors include prior cleaning of the device; both the organic and inorganic load present on the device; the specific type of microbial contamination; the level of microbial contamination; the concentration of the germicide used; the length of time that the device is exposed to the germicide; the physical nature and complexity of the device (hinges, dead-spaces, lumens, etc.); the presence of microscopic biofilms; the temperature and pH of the disinfection agent. The relative humidity of the sterilization process (e.g., steam sterilization vs. ETO) can also have an impact on the efficacy of the disinfection process.

Prior to selecting decontamination agents, it is important to know and understand the various terms used to describe the products. Product labels with the suffix ‘cide’ or ‘cidal’ describe products that are designed for killing action. For example, a germicide is an agent that can kill microorganisms, particularly pathogenic organisms (“germs”).

The term ‘germicide’ includes both antiseptics and disinfectants. Antiseptics are germicides applied to living tissue and skin; disinfectants are antimicrobials applied only to inanimate objects (i.e., surgical instruments). In general, antiseptics are used only on the skin and not for surface disinfection, and disinfectants are not used for skin antisepsis because they can injure skin and other tissues. Virucide, fungicide, bactericide, sporicide, and tuberculocide can kill the type of microorganism identified by the prefix. For example, a bactericide is an agent that kills bacteria. (1–5)

Disinfection, unlike sterilization, is not sporicidal. There are a number of commercially available chemical sterilants (disinfectants) that are approved for use on most reusable medical devices and surgical instruments that will kill spores with prolonged exposure times (usually between three to twelve hours). At similar concentrations but with shorter exposure periods (e.g., 20 minutes for 2% glutaraldehyde), these same disinfectants will effectively kill all microorganisms except large numbers of bacterial spores. These are commonly referred to as high-level disinfectants. It is important to consult the disinfectant manufacturer’s labeling to determine the appropriate concentration and exposure time to ensure 100% kill.

Low level disinfectants can kill most vegetative bacteria, some fungi, and some viruses in a very short period of time (i.e., 10 minutes or less). Again, it is important to always consult the disinfectant manufacturer’s labeling to determine the appropriate concentration and exposure time to ensure 100% kill.

In addition to always following the disinfectant manufacturer’s Instructions for Use (IFUs), it is equally important to ensure that those IFUs have been validated by an independent testing laboratory. In the absence of validated IFUs from the manufacturer, it isn’t possible to be sure that the disinfectant is actually providing 100% kill on every reprocessing cycle.

1 Favero MS, Bond WW. Chemical disinfection of medical and surgical materials. In: Block SS, ed. Disinfection, sterilization, and preservation. Philadelphia: Lippincott Williams & Wilkins, 2001:881-917.

2 Spaulding EH. Chemical disinfection of medical and surgical materials. In: Lawrence C, Block SS, eds. Disinfection, sterilization, and preservation. Philadelphia: Lea & Febiger, 1968:517-31.

3 Simmons BP. CDC guidelines for the prevention and control of nosocomial infections. Guideline for hospital environmental control. Am. J. Infect. Control 1983; 11:97-120.

4 Block SS. Disinfection, sterilization, and preservation. Philadelphia: Lippincott Williams & Wilkins, 2001. 17. Rutala WA, 1994, 1995, and 1996 APIC Guidelines Committee. APIC guideline for selection and use of disinfectants. Association for Professionals in Infection Control and Epidemiology, Inc. Am. J. Infect. Control 1996; 24:313-42.

5 Rutala WA. Disinfection, sterilization and waste disposal. In: Wenzel RP, ed. Prevention and control of nosocomial infections. Baltimore: Williams and Wilkins, 1997:539-93.

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