Which statement about laboratory cultivation of Chlamydia trachomatis is correct?
- A It replicates in the cytoplasm of McCoy cell monolayers forming glycogen-containing inclusions stained by iodine or Giemsa ✓
- B It grows readily on chocolate agar enriched with IsoVitalex after 48 hours of incubation
- C It requires embryonated hen egg yolk sac inoculation as the only available culture method
- D It grows in liquid media containing serum and yeast extract under microaerophilic conditions
Correct answer: A. It replicates in the cytoplasm of McCoy cell monolayers forming glycogen-containing inclusions stained by iodine or Giemsa
Explanation
Chlamydia trachomatis is an obligate intracellular bacterium that cannot be grown on cell-free media. It replicates inside cytoplasmic vacuoles of susceptible cell lines such as McCoy or HeLa cells, where mature inclusions contain glycogen and stain brown with Lugol iodine or blue-purple with Giemsa. Centrifugation of inoculum onto the monolayer enhances infectivity. Yolk sac inoculation was the historical method for LGV strains but is obsolete, and chocolate agar supports Neisseria, not Chlamydia.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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