The method involves placing a standardized paper disc impregnated with a specific concentration of the antimicrobial agent onto the surface of an agar plate inoculated with the test bacterial strain. The plates are then incubated to allow for bacterial growth and diffusion of the antimicrobial agent from the disc into the agar.
After incubation, the plates are examined for the presence of a clear zone of inhibition around the disc. The zone of inhibition represents the area where bacterial growth has been prevented due to the antimicrobial activity of the agent. The diameter of the zone of inhibition is measured and compared to standard reference tables to determine the susceptibility or resistance of the bacterial strain to the antimicrobial agent.
The disc diffusion method provides a qualitative or semi-quantitative assessment of antimicrobial susceptibility. It can be used to screen for the effectiveness of different antimicrobial agents against a particular bacterial strain, to compare the susceptibility of different bacterial strains to the same antimicrobial agent, and to monitor the development of antimicrobial resistance.
This method is commonly employed in clinical laboratories, research settings, and pharmaceutical industries for evaluating the efficacy of antimicrobial agents and guiding appropriate antibiotic therapy in clinical practice.
