Colonies said to have the appearance of a 'fried egg' are characteristic of

• A. Ehrlichia chaffeensis
• B. Mycoplasma genitalium
• C. Mycoplasma hominis
• D. Ureaplasma urealyticum

Answer: (C)

Fried-egg colonies are a classic hallmark of Mycoplasma growth on enriched, cholesterol-containing media (such as PPLO or SP-4). These organisms lack a cell wall, are pleomorphic, and require specialized medium to grow. On such media, colonies appear with a dense outer ring and a clearer center, giving the distinctive fried-egg look.

Among the options, Mycoplasma hominis is the genital Mycoplasma most often described with this fried-egg colony morphology, making it the best match. Ehrlichia chaffeensis is an intracellular organism that doesn’t form visible colonies on routine culture. While Mycoplasma genitalium and Ureaplasma urealyticum are also Mycoplasma species, the fried-egg description is most classically associated with Mycoplasma hominis in conventional teaching.