I am unclear as to how to perform the "D test" on purity plates. Can you please explain this process? Also, is there a recommended QC strain for the "D test"?

Answer

The protocol for performing the D test for inducible clindamycin resistance in staphylococci can be found by clicking here. NCCLS is in the process of identifying a QC strain. In the interim, it is important to check the disks for acceptable potency by performing routine quality control with Staphylococcus aureus ATCC 25923. In addition, a strain of S. aureus that has been shown to have inducible clindamycin resistance can be used for QC.