Tetracycline TET 30 µg (5x 50 discs, Oxoid)

BACKGROUND
Antibiotic susceptibility discs are used for semi-quantitative susceptibility testing of common, fast-growing, and certain fastidious bacteria against antibiotics using the agar diffusion method.

PRINCIPLE OF THE TEST
Filter paper discs impregnated with defined amounts of antibiotics are applied to the surface of a suitable medium (e.g., Mueller-Hinton agar). The culture medium must first be inoculated with a standardized inoculum (EUCAST recommendation: McFarland 0.5) of a fresh pure culture of the bacterial strain to be tested. After a 24-hour incubation, growth is checked, the inhibition zones around the test discs are measured, and compared with the clinical breakpoints for the different antibiotics tested to determine susceptibility (S - Susceptible at standard exposure, I - Intermediate, R - Resistant). The diameter of the inhibition zones corresponds to the susceptibility of the tested bacterial strain to the antibiotic concentration at the edge of the inhibition zone. 

You can find various service documents, such as templates with inhibition zone limits for easy evaluation of the agar diffusion test and a collection of guidelines, in our Media Library. Content and Storage:

·Cartridges each containing 50 test discs
·Store at 2-8° C.

As an alternative to agar diffusion, we recommend agar dilution, which can be partially automated with systems such as the MICRONAUT system, and for which increasingly more precise clinical breakpoints are available. This means that, at least since EUCAST 10.0 (2020), certain antibiotics can only be tested using agar dilution and no longer via agar diffusion (!). We would be happy to advise you on this and help you find the best solution for your needs.