【国外标准】 Standard Test Method for Quantitative Petri Plate Method (QPM) for Determining the Effectiveness of Antimicrobial Towelettes (Withdrawn 2020)

5.1 The glass petri plate provides a closed system for enumeration and easy application of a pre-saturated or impregnated antimicrobial towelette by an analyst.5.2 Inoculation of carriers (five 10 µL spots of microbial suspension) is conducted using a template and a positive displacement pipette, thereby ensuring a precise inoculum level and uniform distribution of inoculum.5.3 A single towelette is tested per carrier, thereby ensuring comparable treatment among carriers and eliminating the likelihood of cross-contamination between carriers.5.4 The circular motion of the product application (wipe outside to inside, lift towelette to invert and wipe inside to outside) is a relevant motion that ensures uniform coverage and contact of disinfectant with the inoculated surface.5.5 The addition of neutralizer to the treated plates ensures thorough neutralization at the end of the product’s contact time. This test method provides a procedure for performing neutralization verification to confirm that the microbicidal and/or microbistatic activity of a test substance has been brought to an undetectable level at the end of the contact time.5.6 The design of the test method minimizes any loss of viable organisms through carrier wash-off.5.7 This test method provides for optional use of an organic soil load as dictated by a product’s label claim.5.8 It is optional to adjust (either dilute or concentrate) the inoculum level to achieve desired control carrier counts and to accommodate different product performance standards.1.1 This test method provides detailed instructions for performing a quantitative evaluation of antimicrobial efficacy of a towelette when challenged against Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella enterica. The method may be used with other microbial strains, though modification may be necessary to accommodate recovery.1.1.1 Antimicrobial towelettes, designed to decontaminate hard, non-porous surfaces, are diverse in size, matrix composition, and packaging.1.1.2 Antimicrobial towelettes also vary in label claims and use directions.1.2 This quantitative method does not differentiate between mechanical removal of inoculum from a surface and chemical inactivation of the test microbe; rather, product efficacy is considered a combination of both attributes of a towelette-based formulation.1.3 It is the responsibility of the investigator to determine whether Good Laboratory Practices (GLP Standards—40 CFR, Part 160 of FIFRA) are required and to follow them when appropriate.1.4 This standard may involve the use of hazardous materials, chemicals and infectious microorganisms and should be performed only by persons with formal training in microbiology.1.5 Strict adherence to the protocol is necessary for the validity of the test results.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 address specific product performance standards established by regulatory authorities; see Section 10, Note 2 for details.1.8 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.