Final answer:
To measure the diameter of a non-circular bacterial zone of inhibition, measure the longest and shortest distances across the zone and use these to provide an average or range. Compare to a standard chart for susceptibility or resistance, but consider the limited information due to variations in drug diffusion and agar properties.
Step-by-step explanation:
When measuring the diameter or radius of a non-circular bacterial zone of inhibition, one must consider the irregular shape of the inhibition zone. Since a non-circular zone does not have a consistent radius throughout, one approach is to measure the longest and shortest distances across the zone to provide an average diameter or radius. Using these two measurements, you can record an average size or provide a range of the diameter of the zone of inhibition, which can then be compared to a standard chart to determine bacterial susceptibility or resistance to antibiotics.
It is important to remember that during a Kirby-Bauer disk diffusion test, the size of the zone of inhibition can be indicative of antimicrobial effectiveness, where a larger zone generally signifies greater inhibition. Nonetheless, due to various factors such as drug solubility, diffusion rate, and agar thickness, these measurements only offer limited information and cannot be directly used to compare drug potencies.