Measurement of the Zone of Inhibition of an Antibiotic

Abstract

In the Disk Diffusion Antibiotic Sensitivity test (The Kirby-Bauer test) a thin film of bacteria applied on a plate is subjected to various antibiotics. The Zone of inhibition is a circular area around the spot of the antibiotic in which the bacteria colonies do not grow. The zone of inhibition can be used to measure the susceptibility of the bacteria to wards the antibiotic. The process of measuring the diameter of this Zone of Inhibition can be automated using Image processing. In this work an algorithm is developed, using Computer Vision, which will detect the zones of inhibition of the bacteria. This work demonstrates an effective approach of measuring the Zone of Inhibition by calculating the radius of the zone by drawing contours and setting the right value of threshold. This work also determines if a particular bacteria is susceptible or resistant to the applied antibiotic using the calculated Zone of Inhibition and the prescribed standard values.