Antisepsis, Disinfection, and Sterilization. Gerald E. McDonnell

Antisepsis, Disinfection, and Sterilization

Method Tuberculocidal Activity of Disinfectants Porcelain penicylinders contaminated with Mycobacterium bovis and exposed to the product; carriers tested for growth/no growth following exposure AOAC Official Method 966.04 Sporicidal Test Method Clostridium sporogenes and Bacillus subtilis cultures (including spores) dried onto porcelain penicylinders and suture loop carriers; exposed to the test disinfectant/sterilant for the required time and incubated to detect the presence/absence of growth; includes an HCl resistance test to confirm the acid resistance of the spores ASTM E1053 Standard Test Method for Efficacy of Virucidal Agents Intended for Inanimate Environmental Surfaces Guidelines on testing of the virucidal activity of a product on an inanimate surface ASTM E2111 Standard Quantitative Carrier Test Method To Evaluate the Bactericidal, Fungicidal, Mycobactericidal and Sporicidal Potencies of Liquid Chemical Germicides Carrier (glass vials) test for the potencies of liquid disinfectants against bacteria and fungi EN 13697 Chemical Disinfectants and Antiseptics. Quantitative Non-Porous Surface Test for the Evaluation of Bactericidal and/or Fungicidal Activity of Chemical Disinfectants Used in Food, Industrial, Domestic and Institutional Areas. Test Method and Requirements Various bacteria (e.g., Pseudomonas aeruginosa and Enterococcus hirae) and fungi (Candida albicans and Aspergillus niger) inoculated onto stainless steel discs in the presence/absence of interfering soil and exposed to the test disinfectant/antiseptic; must demonstrate a ≥10⁴ reduction of bacteria in 5 min and ≥10³ reduction of fungi in 15 min

^aAOAC, Association of Official Analytical Chemists; ASTM, American Society for Testing and Materials; EN, European Norm, from the CEN (European Committee for Standardization).

Finally, in-use testing is designed to test the product or process under the actual conditions of use. These tests can be designed to test biocidal efficiency on a given surface, including routine microbial sampling of a surface using a recovery method (e.g., a swabbing or elution method). The efficiency can be determined before and after the application of a product or process with the estimation of the associated bioburden, which is defined as the population of viable microorganisms on or in a product, surface, or area. In some applications, in-use testing is recommended to actively monitor the success or failure of a product or process over time. Examples include the routine sampling of a reusable medical device, swabbing of a food contact surface, and verification of the operation of disinfection and/or sterilization equipment (examples of test methods are given in Table 1.20).

TABLE 1.20 Examples of simulated-use and/or in-use tests and/or guidelines^a

Reference^b	Title	Summary
ASTM E1837-96	Standard Test Method To Determine Efficacy of Disinfection Processes for Reusable Medical Devices	Simulated-use testing for the effectiveness of a disinfection process for reprocessing reusable medical devices using bacteria, viruses, and/or fungi
ISO 11737-1	Sterilization of Medical Devices—Microbiological Methods—Part 1: Estimation of Population of Microorganisms on Products	In-use testing guidelines for estimation of the population of viable microorganisms (or the bioburden) on a medical device
ISO 14698-1	Cleanrooms and Associated Controlled Environments—Biocontamination Control, Part 1: General Principles and Methods	In-use testing guidelines for the assessment and control of biocontamination within a cleanroom environment
WHO	Guidelines for Drinking-Water Quality	Guidelines for the microbial and chemical safety of drinking water, including water-testing methods for monitoring water disinfection efficacy
ASTM E1174-94	Standard Test Method for Evaluation of Healthcare Personnel Handwash Formulations	Simulation to test the activity of an antiseptic on the hands using an artificial inoculum of Serratia marcescens
ASTM E1173-01	Standard Test Method of an Evaluation of Preoperative, Precatheterization, or Preinjection Skin Preparations	In-use test for the activity of an antiseptic to reduce the resident microbial flora of the skin

^aSimulated testing uses an artificial inoculum, and in-use testing uses the normal bioburden present on a surface or device.

^bISO, International Standards Organization;ASTM, American Society for Testing and Materials;WHO, World Health Organization.

1.4.2.3 BIOLOGICAL, CHEMICAL, AND OTHER INDICATORS

Indicators are routinely used to check the effectiveness of various cleaning, disinfection, and sterilization processes. They include biological, chemical, and other (e.g., mechanical) indicators.

Biological indicators (Fig. 1.23) consist of a standardized population of microorganisms inoculated onto a carrier material. They are particularly widely used in the monitoring and validation of sterilization processes. Bacterial endospores are commonly used as the test microorganisms, as they are generally nonpathogenic and stable and demonstrate high resistance to various sterilization processes (Table 1.21). Defined bacterial strains, obtained from standard culture collections (e.g., the American Type Culture Collection), are used. The intrinsic resistance of the inoculated spore population can vary depending on the culturing methods used and other variables. Therefore, to standardize the use of biological indicators, manufacturers test each batch of indicators to determine the population and the relative resistance to a given sterilization process (e.g., D-value determination at 121’C with saturated steam and at 55^°C, 800 mg of ethylene oxide/liter, and 70% relative humidity for ethylene oxide). Depending on the application, other microorganisms may be used, but to a much lesser extent.

FIGURE 1.23 Example of a self-contained biological indicator.

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