Yersinia pestis — Colony Characteristics
Sheep blood agar
Growth at 24 hours is tiny, almost invisible, shiny gray, translucent “spots.” At 48 to 72 hours, colonies are 1 to 2 mm irregular, gray-white to slightly yellow in color, and have a raised, irregular, “fried egg” appearance, which become prominent as the culture ages.
Clear, lactose negative colonies
|Growth on chocolate agar|
|Brain Heart Infusion Broth|
|Growth is faster at 25 to 28 degrees C than at 37 degrees C. At 25 degrees C growth is suspended flocculent or crumbly clumps, visible at the sides and bottom of the tube with the rest of the media remaining clear.|