Which of the following is a commonly used method for antimicrobial susceptibility testing in microbiology laboratories?

• A. Gram staining
• B. Kirby-Bauer disk diffusion test
• C. ELISA (enzyme-linked immunosorbent assay)
• D. Polymerase chain reaction (PCR)

Answer: (B)

Verified step by step guidance

1. Understand that antimicrobial susceptibility testing is used to determine the effectiveness of antibiotics against specific bacteria isolated from a patient sample.
2. Recognize that Gram staining is a staining technique used to classify bacteria based on their cell wall properties, but it does not test antibiotic susceptibility.
3. Know that ELISA (enzyme-linked immunosorbent assay) is primarily used to detect antigens or antibodies, not to test bacterial susceptibility to antibiotics.
4. Understand that PCR (polymerase chain reaction) is a molecular technique used to amplify DNA sequences and can detect resistance genes but is not a direct method for susceptibility testing.
5. Identify that the Kirby-Bauer disk diffusion test is a standardized method where antibiotic-impregnated disks are placed on an agar plate inoculated with bacteria, and zones of inhibition are measured to determine susceptibility.