An antibiotic strip is a laboratory instrument used to test the susceptibility of bacteria to a range of different antibiotics. It consists of a paper strip that has been impregnated with multiple antibiotics at different concentrations.To perform an antibiotic strip assay, the strip is placed on an agar plate that has been inoculated with a bacterial culture. The plate is then incubated, and after a period of time, the growth of bacteria around the strip is observed. The zone of inhibition, or the area where the bacteria cannot grow due to the presence of the antibiotic, is measured and used to determine the susceptibility of the bacteria to each antibiotic.