ASTM E3321-21

5.1?In the battle to reduce medical device and implant-related infections, prevention of bacterial colonization of surfaces is a logical strategy. Bacterial colonization of a surface is a precursor to biofilm formation. Biofilm is the etiological agent of many implant and device-related infections and once established, microorganisms in biofilm can be up to 1000 times more tolerant to antibiotic therapy. Often the best treatment strategy is removal of the implant or device at a high socioeconomic cost. Catheter associated urinary tract infections (CAUTI) are the most prevalent of the device-related healthcare associated infections. Catheter associated infections account for 37 % of all hospital acquired infections (HAI) and 70 % of all nosocomial urinary tract infections (UTI) in the U.S. 5.2?The purpose of this test method is to direct a user in how to grow, sample, and analyze an E. coli biofilm in a urinary catheter under a constant flow of artificial urine. The test method incorporates operational parameters utilized in similar published methods (4). The E. coli biofilm that grows has a patchy appearance that varies across the catheter. Microscopically, the biofilm is heterogenous, with large clusters in some areas, and flat sheets of cells or even single cells in others. By 24 h, the biofilm is developed in the control catheters. If the goal is to monitor early stage biofilm development, then tubing and effluent samples need to be collected prior to the 24 h sample collection. Monitoring biofilm development requires sampling. The biofilm generated in the Intraluminal Catheter Model is suitable for comparison testing between antimicrobial and control catheters.

1.1?This test method specifies the operational parameters required to assess the ability of antimicrobial urinary catheters to prevent or control biofilm growth. Efficacy is reported as the log reduction in viable bacteria when compared to a repeatable (1)2 1.2?The test method is versatile and may also be used for growing and/or characterizing biofilms and suspended bacteria of different species, although this will require changing the operational parameters to optimize the method based upon the growth requirements of the new organism.

1.3?This test method may be used to evaluate surface modified urinary catheters that contain no antimicrobial agent.

1.4?This test method describes how to sample and analyze catheter segments and effluent for viable cells. Biofilm population density is recorded as log colony forming units per surface area. Suspended bacterial population density is reported as log colony forming units per volume.

1.5 Basic microbiology training is required to perform this test method.

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

1.7?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.

1.8?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.