ASTM E2149-13a

4.1 Chemically bonded, antimicrobial agents are not free to diffuse into their environment under normal conditions of use. This test method ensures good contact between the bacteria and the treated fiber, fabric, or other substrate, by constant agitation of the test specimen in a challenge suspension during the test period.

4.2 The metabolic state of the challenge species can directly affect measurements of the effectiveness of particular antimicrobial agents or concentrations of agents. The susceptibility of the species to particular biocides could be altered depending on its life stage (cycle). One-hour contact time in a buffer solution allows for metabolic stasis in the population. This test method standardizes both the growth conditions of the challenge species and substrate contact times to reduce the variability associated with growth phase of the microorganism.

4.3 Leaching of an antimicrobial is dependent upon the test conditions being utilized and the ultimate end use of the product. For example, water soluble antimicrobials will be prone to removal from the test surface using the method described in Section 4.4 This test method cannot determine if a compound is leaching into solution or is immobilized on the substrate. This test method is only intended to determine efficacy as described in 4.5 and subsequent portions of the method.

4.5 This test method is intended to evaluate antimicrobial agents that are not removed from the surface by the aqueous testing conditions, as evaluated by Section 4.6 The test is suitable for evaluating stressed or modified specimens, when accompanied by adequate controls.

1.2 This test method allows for the ability to evaluate many different types of treated substrates and a wide range of microorganisms. Treated substrates used in this test method can be subjected to a wide variety of physical/chemical stresses or manipulations and allows for the versatility of testing the effect of contamination due to such things as hard water, proteins, blood, serum, various chemicals, and other contaminants.

1.3 Surface antimicrobial activity is determined by comparing results from the test sample to controls run simultaneously.

1.4 The presence of an antimicrobial that requires neutralization is determined by the post-test.

1.5 Proper neutralization of all antimicrobials must be confirmed using Test Methods E1054.

1.6 This test method should be performed only by those trained in microbiological techniques.

1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.8 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.