Antibiotic Susceptibility Test Procedure

1. Obtain a fresh BAP (1 plate per group of 4) and divide it into quadrants.  Label the quadrants with the names of the bacteria as shown in the diagram below. 
   Note:  To complete this experiment, a stock culture of Streptococcus agalactiae and Streptococcus mitis will be provided.  The remaining cultures (Streptococcus pneumoniae, and Streptococcus pyogenes) will be taken from the blood agar plates inoculated in the previous lab. 
2. Using an inoculating loop, pick up a small, isolated colony of Streptococcus pneumoniae from the BAP plate and transfer it to the center of the quadrant labeled Streptococcus pneumoniae.  Spread bacteria around in a circle at least the size of a 50¢ piece. 
3. Repeat step 2 with the remaining 3 bacterial isolates. 
4. Place a taxos P disc (impregnated with optochin) on the Streptococcus pneumoniae and Streptococcus mitis smears. Procedure for dispensing antibiotics.
5. Put a taxos A disc (impregnated with bacitracin) on the Streptococcus pyogenes and Streptococcus agalactiae smears. 
   
6. WITHOUT INVERTING, place the plate in the tray on the side bench.  Incubate the plates at 37oC for 24h.

Rachel Watson, M.S.
AG 5010
766-3524
Cell: 307-760-2942
rwatson@uwyo.edu