identification of Staphylococcus and Streptococcus

these orgs are Gram positive cocci. Strept occur either in chains or as diplococci. Staph occur in grape like clusters.

to differentiate between Staph and Strept
catalase test (3% H2O2)
Staph is pos (immediate bubbling when org is added)
Strept is neg (no immediate bubbling when org is added)

to differentiate between S aureus and S epidermidis
DNAse test (stab inoculation)
S aureus is pos (clear zone around colonies after 1N HCl is added)
S epidermidis is neg (medium turns opaque around colonies after 1N HCl is added)