Which organism is the causative agent of trachoma, and what is its classification?

Explanation

## Causative Agent of Trachoma **Key Point:** Trachoma is caused by *Chlamydia trachomatis*, specifically serovars A, B, Ba, and C. This organism is an obligate intracellular bacterium with a gram-negative cell wall. ### Organism Characteristics | Feature | Details | |---------|----------| | **Causative agent** | *Chlamydia trachomatis* serovars A, B, Ba, C | | **Cell wall** | Gram-negative (but does not stain well with standard Gram stain) | | **Growth requirement** | Obligate intracellular (requires living cells for replication) | | **Replication site** | Cytoplasm of epithelial cells | | **Inclusion bodies** | Giemsa-positive cytoplasmic inclusions | **High-Yield:** *Chlamydia trachomatis* serovars A, B, Ba, and C cause trachoma (chronic keratoconjunctivitis). Serovars D–L cause inclusion conjunctivitis and urogenital infections. **Clinical Pearl:** Trachoma is the leading infectious cause of blindness worldwide, particularly in areas with poor sanitation and limited access to clean water. It remains endemic in parts of Africa, the Middle East, and South Asia.