1. Scope

1.1 This practice may be used to determine the bacterial retention characteristics of sterilizing-grade membrane filters for liquid filtration using process-operating parameters and Brevundimonas diminuta [American Type Culture Collection (ATCC) 19146] or other suitable bacterium as the challenge organism in either the product or a surrogate fluid. It may not always be possible to work with the actual product because of its toxicity, chemical incompatibility, or limited supply. The surrogate fluid should match the product as closely as possible in terms of its physical and chemical characteristics without changing the size and retention characteristics of the challenge microorganism. 1.2 This practice may be used by filter users or filter manufacturers to evaluate the microbial retentivity under process conditions of any membrane filter used for liquid sterilization in the manufacture of pharmaceutical, biopharmaceutical, and biological products. Process validation of sterilizing filtration in the subject industries is required by regulatory agencies to ensure that process fluid contact with the filter under actual process conditions (for example, time, flow rate, temperature, and pressure differential) does not adversely affect the composition, stability, or efficacy of the filtered material, or the retentivity and integrity of the filter, and that the filtration process is capable of producing a sterile filtrate. 1.3 This practice is intended to provide guidance when performing bacterial challenge process validation of sterilizing-grade filters to show that the membrane filter is capable of complete retention of the challenge organism at a minimum challenge level of 1 107 CFU/cm2 of effective filtration area (EFA) under process-operating conditions using actual product or surrogate fluid with the specified filter membrane material and composition. 1.4 Units-The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. 1.5 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.

Keywords

bacterial challenge validation testing; bacterial retention characteristics; BCT; B. diminuta; Brevundimonas diminuta; sterilizing filtration; sterilizing-grade membrane filters

Rationale

This practice is intended to provide guidance when performing bacterial challenge process validation of sterilizing-grade filters to show that the membrane filter is capable of complete retention of the challenge organism at a minimum of 1 x 107 CFU/cm2 of effective filtration area under process operating conditions using actual product or surrogate fluid with the specified filter membrane material and composition.

The title and scope are in draft form and are under development within this ASTM Committee.