S. marcescens are pigmented pink to red, colonies that were pink were isolated and streaked on new plates. The plates from the rinse solution and humidifier cup were both contaminated with pink colonies. A plate from each of the isolated colonies was incubated at 37 C and at room temperature. Colonies from both areas remained a light pink color, and did not turn the characteristic blood red color of S. marcescens. The bacteria from the isolated colonies were looked at under a bright microscope