Disinfectant kill time test

This test was designed to demonstrate log reduction values over time for a disinfectant against selected bacteria, fungi, and/or mold. The most common organisms tested include: Bacillus subtilis, Bacillus atrophaeus, Bacillus thuringiensis, Staphylococcus aureus, Salmonella cholerasuis, Pseudomonas aeruginosa, Aspergillus niger, and Trichophyton mentagrophytes.

Study Outline

The Kill Time test is performed to demonstrate log reduction values over time for a disinfectant against selected bacteria, fungi, and/or mold. The most common organisms tested include: Bacillus subtilis, Bacillus atrophaeus, Bacillus thuringiensis, Staphylococcus aureus, Salmonella cholerasuis, Pseudomonas aeruginosa, Aspergillus niger, and Trichophyton mentagrophytes.

The procedure is derived from disinfectant test methods found in the Association of Official Analytical Chemists (AOAC) and meets log reduction criteria required by the United States Environmental Protection Agency and Food and Drug Association for certain applications.

A tube of disinfectant is placed into a waterbath for temperature control and allowed to equilibrate. Once the tube has reached temperature, it is inoculated to achieve a concentration of approximately 10⁶ CFU/mL. At selected time points (generally five points are used including zero) aliquots are removed and placed into a neutralizer blank. Dilutions of the neutralizer are made and selected dilutions plated onto agar. Colonies are enumerated and log reductions are calculated.

A neutralization study is completed for the organisms and sample types submitted to demonstrate the ability of the media to support organism growth.

Sample Requirements

100 milliliters per lot, minimum

Note: This is a final test volume, dilutions can be made by the laboratory from submitted concentrates. Dilutions for sample preparation are to be included in the test protocol. Additional volumes may be needed for multiple organism testing.

Nelson Experts:

• Kimberlee Dickman 801-290-7858, 800-826-2088

Sample Requirements

100 milliliters per lot, minimum

Note: This is a final test volume, dilutions can be made by the laboratory from submitted concentrates. Dilutions for sample preparation are to be included in the test protocol. Additional volumes may be needed for multiple organism testing.