what is the purpose of bacitracin disk
P urpose and Scope: The bacitracin susceptibility test is used to distinguish Group A streptococci, from other streptococci. When grown on blood agar, Group A streptococci are sensitive to (killed by) the antibiotic bacitracin. With sterile forceps, obtain a bacitracin disk and place inon the inoculated agar at the intersection of the primary and secondary streaks. 2  Tap the disk with forceps to ensure adherence to the agar surface.