Colonies that resemble a fried egg are characteristic of which organism?

Colonies that resemble a fried egg are characteristic of which organism?

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

Answer: (C)

Fried-egg colonies are a classic clue to growth of wall-less bacteria on sterol-containing, enriched media. Mycoplasmas require cholesterol for growth and form colonies with a dense central area and a lighter surrounding zone, giving that fried-egg appearance. Among the organisms listed, Mycoplasma hominis is the one most consistently described with that colony morphology on the appropriate medium. Ehrlichia chaffeensis grows inside host cells and doesn’t produce extracellular colonies, while other Mycoplasma species can exist, the fried-egg pattern is a hallmark feature associated with Mycoplasma hominis in lab culture.

Fried-egg colonies are a classic clue to growth of wall-less bacteria on sterol-containing, enriched media. Mycoplasmas require cholesterol for growth and form colonies with a dense central area and a lighter surrounding zone, giving that fried-egg appearance. Among the organisms listed, Mycoplasma hominis is the one most consistently described with that colony morphology on the appropriate medium. Ehrlichia chaffeensis grows inside host cells and doesn’t produce extracellular colonies, while other Mycoplasma species can exist, the fried-egg pattern is a hallmark feature associated with Mycoplasma hominis in lab culture.