What is the function of the Kirby-Bauer disk diffusion test?

The Kirby-Bauer disk diffusion test is designed specifically to determine the susceptibility of bacteria to various antibiotics. In this test, standardized disks coated with specific antibiotics are placed on an agar plate that has been inoculated with the bacteria in question. After incubation, the effectiveness of each antibiotic is assessed by measuring the zone of inhibition around each disk. This zone reflects how well the antibiotic inhibits bacterial growth, providing valuable information about which antibiotics will be effective in treating an infection caused by the tested bacteria. Hence, the B option accurately represents the main function of the test.

The other options do not accurately describe the test’s purpose. Measuring bacterial growth rate typically involves other methods such as turbidimetry or colony counts, identifying bacterial species requires different techniques like biochemical testing or molecular methods, and quantifying bacterial load usually involves serial dilutions and plating, rather than the disk diffusion approach. Therefore, recognizing the Kirby-Bauer test's role in antibiotic susceptibility is crucial for understanding its significance in clinical microbiology.