Ceftriaxone CTR 30 µg (5x 50 discs, Oxoid)

BACKGROUND
Antibiotic testing discs are used for semiquantitative 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 placed on the surface of an appropriate 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, inhibition zones around the test discs are measured, and compared with clinical breakpoints for the various antibiotics tested to determine susceptibility (S - Susceptible at standard exposure, I - susceptible to 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 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 using agar diffusion (!). We would be happy to advise you on this and help you find the best solution for you.