Mycoplasma and Chlamydia

Often confused topic.

Mycoplasma.

  1. Smallest free living and self replicatingĀ  organism on lab media.
  2. Lack rigid cellwall, so highly pleomorphic.
  3. Bounded by triple layered membrane containing sterol, so they require sterol for growth.
  4. Easily pass through bacterial filters.
  5. Completely resistant to penicillin due to lack of cellwall.
  6. Susceptible to saponin,digitonin and polyene antibiotics like Amphotericin B which form complexes with sterol.
  7. Susceptible to inhibitors of protein synthesis like tetracycline,Aminoglycosides,erythromycin,CChloramphenicol.
  8. Genome of Mycoplasma genitalium-Smallest known genome,first genome to be fully sequenced.
  9. OnĀ  agar mycoplasmas produce colonies with fried egg appearance, with an opaque central and translucent peripheral zone.
  10. Glucose or arginine are main energy sources.
  11. Fail to grow in serum free media.
  12. Beta hemolysis in M.pneumoniae is due to production of H2O2.

Chlamydiae

  1. Obligate intracellular parasite.
  2. Use host ATP and releases ADP.
  3. Fail to grow in cell free media.
  4. Grow on Mc Coy or HeLa cell lines.
  5. Outer cell wall resembles Gram negative bacterial cell wall.
  6. Cell wall has high lipid content,has no typical bacterial peptidoglycan or N.Acetyl Muramic acid.
  7. PBP’s appear on chlamydial cell wall so they are susceptible to penicillin.
  8. Treatment with cell wall inhibitors result in morphologically defective forms but not effective clinically.
  9. Inhibitors of protein synthesis like Erythromycin and tetracyclines are DOC’S.

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