Evaluation of Bactericidal, Yeasticidal, and Fungicidal Efficacy of Disinfectant Products

The efficacy of chemical disinfectants and antiseptics is crucial to ensure safety in various industrial, food, domestic, and institutional applications. Specific efficacy tests are essential to ensure that these products work adequately under practical use conditions. These tests not only confirm that disinfectants are effective against a wide range of microorganisms but also ensure that the products are safe for users and comply with regulations and quality standards. The EN 1650:2020 and EN 1276:2019 standards provide standardized methodologies to evaluate the fungicidal, yeasticidal, and bactericidal activity in food, industrial, domestic and institutional areas. The following describes the test methods, organisms, and culture media used in these standards.

Test Methods

Both standards employ common methods to evaluate the efficacy of disinfectants, including the dilution-neutralization method and the membrane filtration method. These methods allow determining the reduction of viable microorganisms after treatment with the disinfectant under controlled conditions.

The dilution-neutralization method involves mixing the disinfectant with a suspension of microorganisms and an interfering substance that simulates practical conditions. After a specific contact time, a neutralizer is added to stop the action of the disinfectant. Subsequently, the count of viable microorganisms is performed by culturing in appropriate media. This method ensures that the observed reduction in the number of microorganisms is exclusively due to the action of the disinfectant during the established contact time.

The membrane filtration method follows a similar principle, but instead of directly neutralizing the mixture, it is filtered through a membrane to separate the microorganisms. The bacteria or spores retained on the membrane are washed, neutralized, and cultured in an appropriate medium to perform the count of viable colonies. This method is useful when a physical separation of microorganisms is required before the neutralization and culturing process.

Interfering substances, such as bovine albumin, are used to simulate real use conditions of the disinfectant. Under clean conditions, a solution of bovine albumin at a low concentration is used, while under dirty conditions, it is used at a higher concentration to simulate significant organic load.

Test Organisms and Culture Media

Different culture media are used in both tests depending on the type of microorganism and the applied test method.

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