ASTM E2111-Standard Quantitative Carrier Test Method to Evaluate the Bactericidal, Fungicidal, Mycobactericidal, and Sporicidal Potencies of Liquid Chemicals. ASTM E2111-12 (2018).

 

Test accredited by ENAC (National Accreditation Entity).

Given the need for a suitable test method to evaluate the microbicidal activity of chemical products, several simple and quantitative methods have been developed to be used with a wide variety of microorganisms. Among them, this fully quantitative support method evaluates the potency of chemical products used in hard environmental surfaces and medical devices, against vegetative bacteria, fungi, mycobacteria, as well as bacterial spores. This method is not suitable for use with viruses, because relatively high dilutions of the eluate and the need for membrane filtration are required.

The test product is evaluated by inoculating at least ten support discs (for each test substance combination to be tested) with one or more of the following test organisms: Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 15442), conidia of Trichophyton mentagrophytes (ATCC 9533), Candida albicans (ATCC 10231), conidia of Aspergillus niger (ATCC 64958), Mycobacterium terrae (ATCC 15755), spores of Bacillus subtilis (ATCC 19659), or Clostridium sporogenes spores (ATCC 7955), depending on the activity that you wish to evaluate. After drying the previously inoculated discs, they are treated with the substance to be tested. The contact time, the temperature and the concentration of use, or indications on how to apply the product, should be indicated by the client.

The surviving microorganisms in each test are compared to the average of no less than three control supports. The incorporation of controls allows to determine the initial load of the organism in the supports and any loss due to drying. To allow adequate statistical evaluation of results, the size of the test inoculum will be high enough to take into account both the performance standard and the experimental variation in the results.

The test offers the option of incorporating an interfering substance consisting of a mixture of three types of proteins: tryptone, bovine serum albumin and mucin, to represent bodily secretions, excretions or other foreign substances that chemical microbicides can meet under the conditions of use.

The client must indicate a test concentration, the indications on how to add the product, whether or not it is desired to incorporate interfering substance on the inoculum, a temperature and a test time. The applicant for the test must record these requirements in the corresponding form.