ASTM E2197 Disk-Carrier Test for C. difficile

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ASTM E2197 Test: Procedure at a Glance

In this study, efficacy of a test disinfectant is measured qualitatively against various vegetative bacteria, viruses, fungi, mycobacteria, or bacterial spores.  For EPA registration the disinfectant is tested at the lower certified limits (or minimum recommended concentration MRC), a dilution of the test disinfectant will be made if deemed necessary. This method requires there be an organic soil load present in the germ culture used to label carriers. Sterile carriers are inoculated with culture, dried, and then exposed to the test disinfectant at the label claim contact temperature and time.  The carriers are then transferred to neutralizing recovery medium, incubated, and observed for growth or no growth of the test germ. Carriers must be inoculated with approximately 106 colony forming units of the test bacteria and must be tested per lot of disinfectant. Three lots of the test disinfectant, each at the lower certified limit, must demonstrate >99.9999% or 6 log10 kill of these bacteria-labeled carrier.

Test controls are implemented into the study to account for any variables that could affect the test outcomes.  Test controls performed in the study are; assay of the concentration of the germ used to inoculate the carriers,  measure the concentration of the germ as labeled onto the carriers, viability control of test medium, neutralization control, and media sterility.  The assay of the labeled carriers confirms the concentration is within the acceptable range, the viability control confirms media isn’t toxic to the test germs, neutralizing controls validates that the neutralizing recovery medium stops the bactericidal activity of the test disinfectant.

ASTM E2197: Microchem’s Expertise

Standard Quantitative Disk Carrier Test Method/ ASTM E2197- This test method does not require any wiping or rubbing actions, therefore it is not designed to test wiping towelettes.  However this method can be modified to evaluate efficacy for single-use towelettes. EPA requires >99.9999% or 6 log10 kill to demonstrate efficacy for the test product.