Ampicillin AMP 2 µg (5x 50 discs, Oxoid)

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

TEST PRINCIPLE
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 various antibiotics tested to determine susceptibility (S - Susceptible at standard exposure, I - Possibly susceptible at increased exposure, 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 with 50 test discs each
·Store at 2-8°C.

As an alternative to agar diffusion, we recommend agar dilution, which can be partially automated with the MICRONAUT system, for example, and for which there are increasingly more and more accurate clinical breakpoints. That is, at least since EUCAST 10.0 (2020), certain antibiotics can only be tested by agar dilution and no longer by agar diffusion (!). We would be happy to advise you on this and help you find the best solution for you.