These two Petri dish culture plates illustrated, how an agar growth medium is integral in the bacterial identification process. Here, the plate on the left contained chocolate agar medium, while the one on the right contained Thayer-Martin growth medium. The latter was more discriminating as to what it was able to incubate, versus the less discriminating chocolate medium. Both were swabbed with a rectal culture, extracted from a patient suspected of harboring Neisseria gonorrhoeae bacteria. Note how the non-selective chocolate medium, allowed for the proliferation of numerous bacterial types, while the more selective Thayer-Martin medium, with its added antibiotics, allowed for the N. gonorrhoeae bacteria to thrive, while eliminating others that had also been present, as evidenced on the left.