Antimicrobial sensitivity testing. Lab technician analysing inhibition zones on an agar plate inoculated with a Pseudomonas aeruginosa bacteria. Antibiotic discs (white, circles) are placed on a bacterial culture and diffuse into the culture medium. A sensitive species will show a zone of inhibition, while uninhibited bacterial growth will indicate a resistance to a certain antibiotic substance. The bacteria don't show any inhibition to the antibiotics tested.