This Petri dish culture plate contained an unknown growth medium that had been inoculated with a culture composed of Staphylococcus sp. bacteria. Atop the growth medium, antibiotic-impregnated disks had been laid, which gave rise to this example of an antibiotic sensitivity test. The medium was kept at a pH of 7.2. See PHIL 16029, for a view featuring a greater area of this plate.