Which statement about drug efficacy based on the Kirby-Bauer disk diffusion test is true?

The statement that if drug A shows a larger zone of inhibition, it is typically more effective, is correct because the Kirby-Bauer disk diffusion test measures the sensitivity of bacteria to antibiotics by observing the clear area, or zone of inhibition, around an antibiotic-impregnated disk. A larger zone indicates that the antibiotic is more effective at inhibiting the growth of the bacteria in question. This is because a greater area of inhibition suggests that the drug can diffuse further and maintain a higher concentration that is effective in preventing bacterial growth.

It is important to note that while the size of the zone of inhibition is a useful indicator of antibiotic efficacy, it is not the only factor to consider when prescribing treatment. Other aspects such as the patient's medical history, potential side effects, and bacterial resistance patterns also play critical roles in determining the suitability of an antibiotic for a particular infection.