Mycoplasma hominis

Valeria Fabre, M.D.


  • Aerobic, fastidious organism; easier to cultivate than M. genitalium.
    • Differs from bacteria due to smaller size, sterols in the membrane and lack of a cell wall.
    • Due to the lack of a cell wall, M. hominis:
      • Is intrinsically resistant to β-lactams
      • Cannot be detected on Gram stain
    • It differs from M. genitalium because it is intrinsically resistant to 14-member macrolides (erythromycin and clarithromycin; see discussion below).
  • M. hominis grows on blood or chocolate agar plates and broth cultures.
    • Visible colonies in 2 - 5 days.
    • Colonies are very small (0.2mm) and translucent, so that they can be easily missed. They have a "fried egg" appearance on agar [Fig, denser in the center and less dense in the periphery].
    • Communicate with the micro lab if you suspect Mycoplasma hominis infection so they can use media that favors Mycoplasma hominis growth.
      • M. hominis in blood culture systems appears to be inhibited by the anticoagulant polyanethole sulfonate which can be neutralized by adding gelatin to a 1% concentration in the blood culture medium, but this is not done routinely.

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Last updated: February 4, 2023