How the efficacy of disinfectants is tested and evaluated: explanations based on SR EN 14885

In an era where the prevention of nosocomial infections is essential, the correct choice of disinfectant products is not just a matter of legislative compliance, but also of patient safety and economic efficiency. The European standard EN 14885:2022 defines how the microbiocidal efficacy of products for medical, veterinary, food, industrial, domestic, or institutional use is tested and demonstrated.

This guide explains step-by-step what these tests mean and how they can inform purchasing decisions, offering practical examples and clear criteria for choosing disinfectant products.

1. Categories of tests: from laboratory to practice

EN 14885 classifies microbiocidal efficacy tests into three phases:

Phase 1 – quantitative suspension tests

•    Purpose: to demonstrate the product's ability to exhibit bactericidal, fungicidal, yeasticidal, or sporicidal activity.
•    Limitations: does not allow for a direct clinical recommendation; it serves only to identify active substances.

Phase 2 – tests simulating practical conditions

Phase 2 tests are divided into two steps:
•    Step 2.1: suspension tests that confirm the product's efficacy under simulated practical conditions, demonstrating bactericidal, fungicidal, yeasticidal, mycobactericidal, tuberculocidal, sporicidal, virucidal, phagicidal, algicidal, or oocysticidal activity, corresponding to the product's use.
•    Step 2.2: quantitative laboratory tests to establish that a product exhibits bactericidal, fungicidal, yeasticidal, mycobactericidal, tuberculocidal, sporicidal, virucidal, phagicidal, algicidal, or oocysticidal activity when applied to a surface or skin under simulated practical conditions (e.g., on surfaces, instruments, textiles, hand washing and scrubbing).

Note: for disinfectants used in hospitals, Phase 2, Step 2 is essential, because microorganisms on surfaces or skin can be desiccated and their behavior differs from that in suspension.

Phase 3 – field tests

•    Tests performed under real-world conditions. Standardized methodologies are not yet available, but may be developed in the future. 

2. Essential principles for product selection

When evaluating a product for purchase, you must consider the following criteria:

Active concentration
•    The tested product must be equivalent to the one marketed, containing the same active substances in the same amount.
•    Changes to inactive substances must be validated theoretically or through tests to demonstrate that they do not affect efficacy.
•    Tests must be performed at at least three concentrations, including one active and one non-active, to identify the minimum effective concentration.

Contact time
•    Test results must be reported against the validated time.
•    A result for 30 minutes of contact does not guarantee efficacy at 10 minutes, but the reverse is possible if the recommended concentration is the same.

Temperature and special conditions
•    For thermo-chemical products, it is recommended to verify efficacy at the usage temperature and at 20 °C (control A and/or water control) to validate the test.
•    This is essential to demonstrate the product's activity under real hospital conditions.

Safety and regulations
•    Tests must be performed in accordance with European, national, and local safety regulations.

3. How to interpret test results

•    Microbial reduction is expressed in logarithms (lg), e.g., 5 log = 99.999% reduction of microorganisms.
•    Results must be reported relative to the exact test conditions (contact time, concentration, type of microorganism).
•    Tests at multiple concentrations allow for the identification of the minimum effective concentration, saving chemicals and reducing costs.

Note: log reduction is expressed with a single significant digit. If the last digit is ≥5, the preceding digit is increased by one unit.

4. Practical recommendations for procurement

a.    Request detailed test reports, including Phase 2, Steps 1 and 2
b.    Verify the equivalence of the tested product with the one marketed
c.    Evaluate the spectrum of efficacy in relation to the infectious risks in your facility
d.    Ask for clarifications regarding special conditions: temperature, contact time, types of microorganisms tested, presence of organic substances (proteins, blood)
e.    Use the results to choose products that offer real safety and proven efficacy

Applying these criteria ensures that the investment in disinfectant products is not only compliant with legislation but also safe and clinically and economically efficient.

Understanding the stages and tests provided by EN 14885 is essential for the correct selection of disinfectant products. Applying these principles contributes to ensuring product efficacy, meeting standards, and optimizing resources, regardless of the field of application.

This material is for informational and explanatory purposes and does not reproduce the SR EN 14885 standard. For official application and legal compliance, it is necessary to consult the official version of the standard.

Bibliography:

ASRO (2022). SR EN 14885:2022 – Chemical disinfectants and antiseptics – Application of European Standards for chemical disinfectants and antiseptics.

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