What is an Antibacterial Test?
The antibacterial test, also known as the antibacterial examination, is a method conducted to assess the antibacterial effects of a specific substance on bacteria. This test evaluates the ability of the material to prevent bacterial growth or eliminate bacteria, especially used in pharmaceutical, cosmetic, hygiene, food, and medical industries.
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Antibacterial Testing for Hand Sanitizers
The antibacterial test for hand sanitizers is a process conducted to evaluate the effectiveness of these products in eliminating or inhibiting the growth of bacteria and microorganisms on the skin surface. Hand sanitizers should be effective against common and pathogenic bacteria such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus).
Antibacterial Test Methods for Hand Sanitizers
The antibacterial test for hand sanitizers is conducted according to the INSO 8512 standard.
Contact Plate Method In this method, the subject’s hand is artificially contaminated, and then the sanitizer is used to cleanse the hand surface. After a specific time, the hand surface is touched to a culture medium to transfer any remaining bacteria. The culture medium is then incubated, and after a specified time, the number of grown colonies is counted. A reduction in colony count indicates the sanitizer’s effectiveness.
Serial Dilution Method In this method, the sanitizer is diluted to various concentrations. Each concentration is applied to the targeted bacteria, and after some time, samples are transferred to the culture medium. The minimum concentration that can stop bacterial growth is called the Minimum Inhibitory Concentration (MIC).
Disk Diffusion Assay This method is similar to the standard disk diffusion methods. Paper disks soaked in the sanitizer solution are placed on a bacterial culture medium, and after incubation, an inhibition zone (a bacteria-free area) around the disks is measured. This method shows how well the sanitizer can inhibit bacteria at a certain distance from the disk.
Antibacterial Testing for Detergents
The antibacterial test for detergents is conducted according to the INSO 19708 standard.
The antibacterial test for detergents is performed to assess the antibacterial effects of these products on various surfaces. This test is crucial in ensuring the quality of detergents and their ability to remove or inhibit bacterial growth, especially in hygiene, food, and medical industries that require high cleanliness and safety standards.
Antibacterial Test Methods for Detergents
There are several methods for performing antibacterial tests on detergents, including the following:
Contact Time Test In this method, target bacteria like Staphylococcus aureus and Escherichia coli are cultured on a surface (such as metal or plastic). Then, the detergent is applied to the surface. After a specified time (e.g., 5, 10, or 15 minutes), the surface is washed and transferred to the culture medium to count the remaining bacteria. This test shows the detergent’s effect on bacteria over different time periods.
Serial Dilution Method In this method, the detergent is diluted at various concentrations, each mixed with a bacterial culture solution. The mixture is then incubated to observe bacterial growth. The minimum concentration that can stop bacterial growth is known as the Minimum Inhibitory Concentration (MIC). This method is suitable for evaluating the detergent’s effectiveness at different concentrations.
Disk Diffusion Assay Similar to the disk diffusion methods used in pharmaceutical tests, here, paper disks soaked in the detergent are placed on the bacterial culture medium. After a specific time, if the detergent is effective, an inhibition zone (bacteria-free area) appears around the disks. The size of this zone indicates the antibacterial strength of the detergent.
Surface Culture Test This method is mainly used for detergents applied on surfaces. The target surface is initially contaminated with bacteria and then cleaned with the detergent. After a specified period, samples are taken from the surface and placed in the culture medium. This test is particularly useful for evaluating the detergent’s effect in practical and surface conditions.
Antibacterial Testing for Disinfectants
The antibacterial test for disinfectants is conducted according to the INSO 11798 standard.
The antibacterial test for disinfectants evaluates the efficacy and antibacterial effects of disinfectant products like sprays, solutions, gels, and various disinfectant materials. This test is crucial for ensuring these products can kill or inhibit bacterial growth in sensitive environments like hospitals, the food industry, and public places.
Common Methods for Antibacterial Testing of Disinfectants
Several standard methods are used for antibacterial testing of disinfectants:
Contact Time Method This method evaluates the duration a disinfectant must stay in contact with a contaminated surface to be effective. Target bacteria, like Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), are cultured on a surface, and the disinfectant is applied for different times (e.g., 5, 10, 15 minutes). After each time interval, samples are taken and re-cultured. Finally, by counting the bacterial colonies, the effectiveness of the disinfectant over different periods is evaluated.
Minimum Inhibitory Concentration (MIC) In this method, the disinfectant is diluted at various concentrations, with each concentration mixed with bacteria. This mixture is incubated to observe bacterial growth. The minimum concentration that fully stops bacterial growth is marked as the MIC. This method is very useful for assessing disinfectant strength.
Disk Diffusion Method In this method, paper disks soaked in the disinfectant solution are placed on the bacterial culture medium. If the disinfectant is effective, a bacteria-free zone (inhibition zone) appears around the disks. The size of this area indicates the disinfectant’s antibacterial power. This method is often used to compare several disinfectants in a single test.
Colony Count Test This method is used to measure the reduction in bacterial population. Bacteria are first grown in a liquid medium, and then the disinfectant is added. After a specified period, a sample is taken from the solution and spread on a culture medium. The number of colonies grown after incubation is counted, and the difference between the initial and final colony count indicates the disinfectant’s efficacy.
Surface Culture Method In this method, surfaces such as metal or plastic are artificially contaminated with bacteria. The disinfectant is then applied to the surface. After a specified time, samples are taken from the surface and transferred to a culture medium to check if the bacteria are still viable. This method is suitable for evaluating disinfectants under real conditions (e.g., disinfecting hospital or industrial surfaces).
Disk Diffusion Method for Antibacterial Testing
The Disk Diffusion Method for antibacterial testing is conducted according to the ISIRI 5875 standard.
The antibacterial test using the Disk Diffusion Method is a common method for assessing the antibacterial effectiveness of materials. This method is particularly used for evaluating the effects of antibiotics, disinfectants, and other antibacterial agents on bacteria.
Steps in Performing the Disk Diffusion Test
Preparation of Culture Medium and Bacteria: First, the agar medium is prepared, and the target bacteria (such as E. coli or S. aureus) are evenly spread across the surface of the medium.
Placement of Disks Soaked in Antibacterial Solution: Small paper disks are soaked in the antibacterial solution or antibiotic and then placed on the culture medium surface. Each disk represents a sample with a specific concentration of the antibacterial agent.
Incubation: The Petri dishes (culture plates) are placed in an incubator at an appropriate temperature, allowing the bacteria to grow and the antibacterial effects to be observed.
Examining Results and Measuring Inhibition Zone: After a specified time, an inhibition zone (a bacteria-free area) appears around the disks. The diameter of this zone indicates the strength of the antibacterial agent; the larger the zone, the more effective the agent is at inhibiting bacterial growth.
Minimum Bactericidal Concentration (MIC-MBC) Test
The Minimum Bactericidal Concentration (MIC-MBC) test is conducted according to the ISIRI 5875 standard.
The MIC and MBC tests are performed to evaluate the antibacterial strength of a substance. This method is particularly used in research on antibiotics, disinfectants, and antibacterial compounds to determine the lowest concentration that can inhibit or kill bacteria.
Steps in Performing MIC and MBC Tests
Preparation of Serial Dilutions: First, serial dilutions of the desired antibacterial agent are prepared to achieve various concentrations.
Adding Bacteria to Dilutions: In each tube or well containing different dilutions, a bacterial solution is added. These mixtures are then incubated.
Measuring MIC: After incubation, the lowest concentration that can fully stop bacterial growth is considered the MIC. Typically, the absence of turbidity indicates growth inhibition.
Measuring MBC: To determine the MBC, a sample from tubes with no bacterial growth (at MIC) is transferred to a fresh culture medium. The lowest concentration that completely kills bacteria and shows no regrowth in the new culture is considered the MBC.
NikooPharmed’s affiliated laboratory offers a wide range of antibacterial tests to evaluate the quality and effectiveness of antibacterial products, using advanced equipment and a team of experienced specialists.
NikooPharmed laboratory always provides reliable results to promote public health and maintain hygiene in society, and it is ready for extensive collaboration with related industries and organizations.
Source:nlm