Question

How could you determine if one of the antibiotics used in the Kirby-Bauer experiment is bacteriastatic or bacteriocidal? Help please, I don’t know how to provide a specific explanation with detail.

Answer 1

In the kirby-bauer experiment also known as disc diffusion assay, first we plate a bacterial culture and then incubate it overnight with antibiotic discs. A clear area is observed around the antibiotic disc which denotes the antibiotic has a inhibitory role on the growth of the bacteria in that region. In order to understand whether the antibiotic is bacteriostatic or bacteriocidal,we can take a small sample from that zone of inhibition and streak on a fresh agar plate. If after incubation we find growth of that bacteria in that fresh agar plate then the corresponding antibiotic that was used was bacteriostatic but if no such growth is observed then the respective antibiotic was bacteriocidal. We must keep in mind that proper sterile condition is maintained and there is no contamination.

bacteriocidal means an agent that kills the bacteria.

bacteriostatic means an agent that stops or inhibits the growth of the bacteria.