Which Antimicrobial Efficacy Study is best for your product?
Anja Friedrich, BSL BIOSERVICE GmbH (a Eurofins partner laboratory), afriedrich@bioservice.com
The increasing number of infection rates is a severe problem in health care facilities. Medical devices coated with or including antimicrobial agents contribute to prevent infections.
To address this, BSL BIOSERVICE offers numerous test systems under ISO 17025, GLP and/or GMP to examine the antimicrobial efficacy of medical devices. The suitable test design is chosen depending on the material of the product and the aim of the study.
The following test systems serve the manufacturers to show the antimicrobial effects.
The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) are evaluation criteria for solutions and soluble products. A dilution series of the product is examined with a test strain by a microdilution method in 96-well plates. The lowest concentration inhibiting bacterial growth (MIC) or the reduction of the bacterial growth to 99.9 % (MBC) are determined.
For a Direct Contact Test, solid materials can be inoculated directly with a test organism. Whereas with the Dynamic Contact Test, samples of surface-bound material are shaken in the bacterial suspension. In both tests the antimicrobial effect is shown by the reduction of the microbial count within a defined time interval in comparison to a reference material.
Alternatively, solid materials are incubated on agar plates with the test strain, Agar Diffusion Test. Bacterial growth inhibition zones indicate the antimicrobial activity and are evaluated by a score system.
Regarding the Proliferation Assay, bacterial cells adhere to the material. In a second incubation step, the time-proliferation curve of daughter cells is determined by measurement of the optical density. Antimicrobial agents delay the bacterial growth.
The results of the studies help the customers for registration of their products or for marketing purposes.
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