Bacitracin 0.04 U/mL (1x 50 discs, BD)

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

TEST PRINCIPLE
Filter paper discs impregnated with defined amounts of antibiotics are applied to 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, 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, a collection of guidelines, and application videos in our media library.

Contents and Storage:
Cartridges with 50 test discs each.
Store at 2-8° C.

Note: BD system cartridges are only compatible with BD dispensers (Becton Dickinson).

As an alternative to agar diffusion, we recommend agar dilution, which can be semi-automated, for example, with the MICRONAUT system, and for which there are increasingly more and more precise clinical breakpoints, i.e., since EUCAST 10.0 (2020) at the latest, 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.