The present invention provides a method of detecting thermonuclease-positive staphylococci that does not require inactivation of DNase-positive/TNase-negative bacteria with heat. The method includes (a) providing a culture medium selective for growing staphylococci; (b) inoculating the culture medium with a sample; (c) incubating the inoculated culture medium under conditions effective to promote the growth of staphylococci; (d) providing an indicator system that produces a differentiable, detectable signal in the presence of thermonuclease-positive staphylococci; (e) contacting the indicator system with the inoculated, incubated culture medium, thereby forming a detection assembly; (f) incubating the detection assembly under conditions effective for generating the differentiable, detectable signal; and (g) detecting the detectable signal.The present invention also provides a culture medium for the selective identification of Staphylococcus aureus. The culture medium includes at least one first selective agent that selects for growth of staphylococci; at least one second selective agent for differentiating Staphylococcus aureus from other staphylococci; at least one first indicator for indicating the presence of staphylococci; and at least one second indicator for differentially indicating the presence of non-staphylococci bacteria. The present invention also provides a method of selectively identifying Staphylococcus aureus in a sample by using the culture medium of the present invention.