Rapid evaluation of disinfectant activity: a semiautomated bioluminescent ATP assay

by Pilar Visa, Eurofins Biolab S.L.U., Spain

Figure 1. Inactivation curve for Staphylococcus aureus with increasing concentrations of a benzalkonium chloride at contact time of 5 minutes

Figure 2. Example of design of experiments

Culture-based microbiological methods currently used for the evaluation of disinfectant activity under simulated practical conditions of use are labourious and lengthy. These tests, generally known as suspension and carrier tests, include several manual steps, and their execution requires a lot of time and material. Therefore, they allow only a few sets of conditions to be tested for a given product in a single run.

Eurofins Biolab now offers a new in-house developed semiautomated rapid method for the evaluation of the bactericidal and yeasticidal activity of disinfectants. The new test's approach consists in scaling-down to 96 micro-well plates of the EN standard suspension and carrier tests procedures. After the contact time with the disinfectant, the quantity of viable microbial cells is calculated within a few minutes by ATP quantification with a luminometer, through luminescence measurement.

The validation study, performed by comparison to the EN standard tests, showed that the new assay evaluates the activity of biocides as well as the EN standards, but it allows a larger number of test conditions to be efficiently analysed, with a very high reproducibility as it is a semi-automated procedure.

The new assay can be used to accurately assess the lowest active concentration of a disinfectant and to compare the microorganisms' susceptibility via inactivation curves. Since this procedure allows testing in the same run many conditions for the same microorganism, temperature and contact time, it is a very useful screening tool.

Eurofins' rapid assay scientific advancements with a full description of this new assay and the results of the validation study were published in April 2012 by the Journal of Applied Microbiology.

To find out how Eurofins can assist your testing needs, contact: GMP_EU@eurofins.com

Reference

Aragonès, L., C. Escudé, P. Visa, L. Salvi and L. Mocé-Llivina. "New insights for rapid evaluation of bactericidal activity: a semi-automated bioluminescent ATP assay". Journal of Applied Microbiology. 2012