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Time Kill Test

Time Kill Test

A Time Kill study measures the antimicrobial activity of the tested product over time.  It can be used to measure the antimicrobial activity of a wide variety of products such as hand sanitizers, antiseptic wound gels, mouth washes, and any other products that are expected to have microbiocidal properties.  A Time Kill study is a generalized solution-based challenge study where the challenge organisms and time points are determined based on clinical relevance for the product being tested.  It provides a quantitative kinetic kill model for the selected organisms and time points.  This test complies with the ASTM Standard E 2315-03, the Standard Guide for Assessment of Antimicrobial Activity Using a Time-Kill Procedure.  Nelson Laboratories has extensive experience working with a wide variety of organisms and provides scientifically sound data by plating in triplicate and offering multiple replicate testing.  We also have the resources to get samples tested with minimal wait time. 

Applicable Standards

  • ASTM E2315

Test Options

Ask an expert for a specific consultation on your product. If you are ready to submit your samples for testing, click here to fill out the Sample Submission Form.

Code Test Request Quote
DIS110 General Kill Time Test: Protocol & Report Fee Add
DIS115 General Kill Time Test Fee: Per variable (time pts, orgs., product) Add
DIS110 - General Kill Time Test: Protocol & Report Fee
DIS115 - General Kill Time Test Fee: Per variable (time pts, orgs., product)

Study Outline

Individual test samples and positive controls are set up for each specific organism. At 0 hour, the test samples and positive controls are individually inoculated with the organisms to reach a specified concentration, usually ≥1.0 x 106 CFU/mL. The volume of the inoculum used should not exceed 5.0% of the volume of the product. The positive controls and samples are immediately assayed and the inoculation concentration is determined by serial dilution and standard plate count procedure.

At the specified exposure times, an aliquot of the inoculated test sample is removed and assayed for growth. The concentration of organism remaining in the sample is determined by standard plate count procedure.  At the longest exposure time, an aliquot of the positive control is assayed in addition to the test sample aliquot.

Plate counts from each time point are compared to those seen in the 0 hour positive control. Reductions in CFU/mL are converted to log reduction values for assessing the antimicrobial effectiveness of the samples.
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