HardyDisk™ Bacitracin Differentiation Disks are used in the presumptive identification of group A, beta-hemolytic streptococci. The test differentiates group A streptococci from other Lancefield groups of hemolytic streptococci by inhibiting the growth of group A streptococci around a disk containing approximately 0.04units of bacitracin.
Maxted reported a rapid diagnostic agent for the presumptive identification and differentiation of group A streptococci from other beta-hemolytic streptococci.(1) He tested over 3,0000 strains and found group A streptococci to be more sensitive to bacitracin than other beta-hemolytic strains. His findings showed that 99.0% of group A streptococci were inhibited and 95.3% of non-group A beta-hemolytic streptococci were not inhibited.(1)Levinson and Frank, and Streamer, et al., later confirmed Maxted's findings that group A streptococci proved more sensitive to bacitracin than other beta-hemolytic streptococci.
Each HardyDisk™ Bacitracin Differentiation Disk is prepared by impregnating approximately 0.04units of bacitracin onto a high quality 6mm diameter filter paper disk.