ASTM E3151-18

5.1 Although a number of standardized tests currently exist for assessing the antimicrobial activity of treated polymers and textiles, these are optimized for specimens that readily absorb the test inoculum or that have a flat surface on which the inoculum can be placed, and their use for specimens with tubular geometries or for small quantities (less than 0.5 g) of yarns or fibers requires significant manipulation of the specimen.

5.2 To adapt these methods for evaluating tubes, fiber, and yarn specimens requires distorting tubular specimens to create a flat surface or using unacceptably large quantities of fiber or yarn specimens. Rendering a test specimen having tubular geometry to a flat surface will limit its surface area available for exposure during the test and may require dissection of the specimen, which unacceptably alters it from its original state. Testing of treated fiber and yarn specimens using available standardized methods typically requires large quantities of material (greater than 0.5 g) that may not be available. In both cases, such manipulations may result in misleading results that do not reflect the antimicrobial efficacy of an unmodified specimen.

5.3 This method provides an environment in which the inoculum remains in intimate contact with the surfaces of these types of test specimens, exposing both the intra- and extraluminal surfaces of tubular specimens without significant modification, and requiring only small quantities of fibers or yarns to perform testing.

5.4 Classical antimicrobial test methods generally quantify the population or concentration of microorganisms that survive exposure to specimens treated with an antimicrobial agent without distinguishing whether the surviving microorganisms were in a planktonic or adhered/biofilm state.

5.5 This test method is a batch-based system in which test specimens are exposed to a continuous, minimal fluid shear environment in the presence of the challenge inoculum. The appropriateness of this simulated environment relative to the intended end-use of the test material should be evaluated prior to testing.

5.6 Although this method is designed to provide an initial assessment of the antimicrobial activity exhibited by a material and its ability to resist microbial colonization under very specific test parameters, these conditions may not be representative of all environments to which the specimen may be exposed during its intended end-use. Various test parameters specified in this method can be modified to evaluate a material under conditions that may better simulate end-use environments, but such alterations of the method must be clearly described when reporting results.

1.1 This test method is designed as an 1.1.1 The difference in number between the planktonic microbial population recovered from the treated test specimen and the population recovered from the control test specimen is the measure of the antimicrobial activity.

1.1.2 The measure of the ability of the treated test specimen to resist biofilm development is the difference between the adherent microbial population recovered from the treated test specimen and the adherent microbial population recovered from the control test specimen.

1.2 Testing is to be performed by individuals trained in microbiological techniques under appropriately controlled conditions to ensure the integrity of results and personnel safety.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.