Final answer:
The Kirby-Bauer test is a method used to determine the susceptibility of bacteria to antibacterial drugs by measuring the zone of inhibition around impregnated disks on an agar plate.
Step-by-step explanation:
Kirby-Bauer Disk Diffusion Test
The Kirby-Bauer test assesses the antimicrobial susceptibility of bacteria to antibacterial drugs. This method involves placing filter paper disks impregnated with known amounts of antibacterial agents on a Mueller-Hinton agar plate. A bacterial lawn is inoculated on the plate, and as bacteria grow, the antibiotic diffuses from the disks into the agar. The zone of inhibition—a clear area around a disk where bacteria do not grow—is measured after incubation. The diameters of these zones are compared with standardized charts to determine whether the bacterium is susceptible or resistant to the antibiotic.
Thus, the Kirby-Bauer test does not evaluate the ability of a microorganism to secrete an antibiotic but instead tests the effectiveness of antimicrobial drugs against specific microorganisms. The results of this test help clinicians choose appropriate antibacterial therapy by identifying drugs that are effective in inhibiting the growth of the pathogen in question.
To predict the therapeutic effectiveness of an antimicrobial drug in a patient using the Kirby-Bauer assay, clinicians consider the size of the zone of inhibition. If a significant inhibition zone is observed, this suggests that the organism is susceptible to the drug, which may indicate potential therapeutic effectiveness in treating infections caused by that organism.