DISNFECTION AND STERILIZATION

General Description

The purpose of this Guidance Document for Disinfectants and Sterilization Methods is to assist lab personnel in their decisions involving the judicious selection and proper use of specific disinfectants and sterilization methods.

Introduction

The purpose of this Guidance Document for Disinfectants and Sterilization Methods.

It is to assist lab personnel in their decisions involving the judicious selection and proper use of specific disinfectants and sterilization methods. For information concerning the proper disposal of all disinfected or sterilized waste, please refer to the Generators’ Guide to Hazardous Material / Waste Management.

 

Definitions

Antisepsis: A process involving the destruction or inhibition of mico-organisms in living tissue thereby limiting or preventing the harmful effects of infection.

Antiseptic: Typically an antiseptic is a chemical agent that is applied to living tissue to kill microbes. Note that not all disinfectants are antiseptics because an antiseptic additionally must not be so harsh that it damages living tissue. Antiseptics are less toxic than disinfectants used on inanimate objects. Due to the lower toxicity, antiseptics can be less active in the destruction of normal and any pathogenic flora present.

Autoclave: An autoclave is a high pressure device used to allow the application of moist heat above the normal-atmosphere boiling point of water.

Biocidal: Active substances and preparations which serve to repel, render harmless or destroy chemically or biologically harmful organisms.

Biocide: Substance or chemical that kills biological organisms.

Decontamination: The killing of organisms or removal of contamination after use, with no quantitative implication, generally referring to procedures for making items safe before disposal.

Disinfectant: A germicide that inactivates virtually all recognized pathogenic microorganisms but not necessarily all microbial forms. They may not be effective against bacterial spores.

Disinfection: A procedure of treatment that eliminates many or all pathogenic microorganisms with the exception of bacterial spores.

Germicide: An agent that destroys microorganisms, particularly pathogenic microorganisms.

Pathogenic: A microbe or other organism that causes disease.

Sanitization: The process of reducing microbial contamination to an acceptable “safe” level. The process of cleaning objects without necessarily going through sterilization.

Steam Sterilization: Autoclave, the process of sterilization by the use of heated steam under pressure to kill vegetative microorganisms and directly exposed spores. Common temperature and pressure for being effective is 121°C (250°F) at 15 psi (pounds per square inch) over pressure for 15 minutes. Special cases may require a variation of the steam temperature and pressure used.

Sterilization: The complete elimination or destruction of all forms of life by a chemical or physical means. This is an absolute not a relative term.

A. Disinfectants

The information presented in this section will provide a general guideline for selecting a particular disinfectant for use with a given agent.

The best way of ascertaining the suitability of a disinfectant against a particular agent is to challenge that agent with the disinfectant at the manufacturer’s recommended concentration. A brief description of the mode of action of each class of chemical disinfectant is given below.

Although physical methods are often superior to chemical disinfection / sterilization, it is not practical to autoclave or subject many items to high heat, especially if the items can be damaged through repeated exposure to heat. Treatment of inert surfaces and heat labile materials can be accomplished through the use of disinfectants, provided that the following factors are considered:

type and level of microbial contamination

concentration of active ingredient

duration of contact between disinfectant and item to be disinfected

pH

temperature

humidity

presence of organic matter or soil load

The interplay of these factors will determine the degree of success in accomplishing either disinfection or sterilization. In all situations, review the manufacturer’s recommendations for correct formulation and use. Do not attempt to use a chemical disinfectant for a purpose it was not designed for.

Most Environmental Protection Agency (EPA)-registered disinfectants have a 10-minute label claim. However, multiple investigators have demonstrated the effectiveness of these disinfectants against vegetative bacteria (e.g., Listeria, Escherichia coli, Salmonella, vancomycin-resistant Enterococci, methicillin-resistant Staphylococcus aureus), yeasts (e.g., Candida), mycobacteria (e.g., Mycobacterium tuberculosis), and viruses (e.g. poliovirus) at exposure times of 30–60 seconds. Federal law requires all applicable label instructions on EPA-registered products to be followed (e.g., use-dilution, shelf life, storage, material compatibility, safe use, and disposal).

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