1.1 This guide covers examples of a basic method to measure the changes of a population of aerobic microorganisms within a specified sampling time when tested against antimicrobial test materials in vitro. Several options for organism selection and growth, inoculum preparation, sampling times and temperatures are provided. When the basic technique is performed as a specific test method it is critical when evaluating the results to ensure that such variables have been standardized. Antimicrobial activity of specific materials, as measured by this technique, may vary significantly on variables selected. It is important to understand the limitations of in vitro tests, especially comparisons of results from tests performed under different circumstances. As an example, test results of microorganisms requiring growth supplements, or special incubation conditions, may not be directly comparable to more robust organisms under the conditions of a single procedure.

1.2 Knowledge of microbiological techniques is required for this test.

1.3 The values stated in SI units are to be regarded as standard.

1.4 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 requirements prior to use.