Bactericide efficacy test

Nowadays, due to the great progress of technology, new materials are being developed with increasingly innovative use cases. As a consequence, in many cases the response of these materials to adverse environmental conditions, such as high temperatures or extreme humidity, is unknown. Due to the lack of knowledge of the response of these new materials, it is essential to have the necessary tools to characterize the properties of the new materials. But not only the physicochemical properties are important in the control of new materials, but there are other properties that become very important when the materials come into contact directly or indirectly with people and can affect their health. Among others, it is important to highlight the evaluation of the response of materials with the microbiological world. Therefore, in this post, we are going to explain what they consist of and the importance of bactericide efficacy tests.

At ATRIA, we perform bactericidal efficacy tests to validate the performance of materials with antimicrobial properties. We tailor each study to meet the specific needs of our clients, whether by following current regulations or developing customized methodologies. If you need to verify the effectiveness of a material under real conditions, Contact us!

How does the bactericidal efficacy test work and what is its purpose?

It is important to know the concept of bactericidal activity in order to evaluate the properties of new materials. First of all, it is necessary to differentiate between bactericidal activity and bacteriostatic activity. The bactericidal activity of a material is related to its ability to kill bacteria. These are substances that inhibit the enzymes that allow bacteria to survive. On the other hand, the bacteriostatic activity of a material is related to its ability to stop the growth of bacteria by inhibiting the synthesis of proteins involved in their propagation.

Therefore, a bactericide efficacy test consists of analyzing the capacity of a material to kill bacteria when subjected to environmental conditions of bacterial proliferation.

Parameters we control in a bactericide efficacy test

The most important parameters that define a bactericide test are those that allow us to ensure the growth of bacteria on our material. Therefore, it is essential to know which parameters directly influence the survival of bacterial activity in a controlled environment. The most important are the following:

• Type of bacteria. Generally, the behavior is evaluated with low hazard bacteria, e coli type, because they are the most accessible at laboratory scale. However, it is also necessary to take into account the possibility of studying other types of bacteria, especially if the material under study is present in locations that may affect health. 
• Bacterial contact. It is important to note that contact with bacteria can occur continuously, depositing a colony of bacteria on the surface of the material and evaluating their proliferation, or by punctual contact, evaluating the adhesion capacity of the microorganisms.

• It is important to note that temperature is a determining factor for bacterial growth, since below 4 ºC, bacterial growth is retarded and above 63ºC, bacteria are destroyed. 

• The humidity of the environment also affects bacterial growth. More than 90% relative humidity is necessary for optimal growth conditions. 

• Time. In general terms, bacterial growth is usually measured within 24 hours. It is important to note that, in some bacterial growth tests, it is necessary to evaluate bacterial growth at 48 hours, as a maximum time. In these periods of time, the necessary time is given to evaluate if the bacterial colonies are growing correctly. 

• The optimum pH for bacterial growth depends on the type and family of bacteria. Generally, the optimal pH range for bacteria is from 6 to 8, with some bacteria preferring low pH (around 3) and only a few preferring pH higher than 8. 

• Like pH, the optimal nutrients depend on the type of bacteria, especially whether they are aerobic or anaerobic organisms. Generally speaking, bacteria need water, a carbon source, a nitrogen source and some mineral salts to grow.

How to perform a bactericide efficacy test

When defining a bactericide assay in the most optimal way possible, two essential points must be taken into account:

• Which materials may be susceptible to bacterial growth and which parts of them will be in contact with bacteria. In many cases, materials have critical areas that are more susceptible to bacterial growth, either because of their geometry or their accessibility.
• What conditions of use you want to evaluate in the materials. It is important to define in which state the bacterial growth is to be evaluated. That is to say, if we want to evaluate the material in its initial state, with the objective of studying the performance of the new materials, or after applying an accelerated aging process, with the purpose of evaluating the resistance of the new materials to environmental conditions.

Our bactericide efficacy testing service

At ATRIA we have extensive experience in evaluating the bactericide efficacy of new materials, from general cases supported by current regulations to specific cases where the methodology is defined in a customized way.

For each case study, we analyze the technical scenario proposed by the client and review the current regulations in order to adjust the study to be performed as much as possible. For example, if the objective is to validate a new bactericidal paint applied in an outdoor location, it is necessary to review the regulations that apply to these environmental conditions. On the other hand, if we are developing new materials and we do not have a defined application yet, bactericidal efficacy tests can be performed under general conditions, in order to evaluate improvements in our material.

What materials and parts can be tested in a bactericide efficacy test?

Bactericide tests can be applied to any material, from liquids applied on inert surfaces to materials coated or additivated with bactericidal agents. The most important factor is the possibility of taking a sample of our material that can be subjected to controlled environmental conditions in order to analyze bacterial growth.

Do you want to perform bactericide efficacy tests on any of your projects? Contact us!