Adult inclusion conjunctivitis is primarily caused by Chlamydia serotypes which of the following?

• A. D-K
• B. A-C
• C. E-F
• D. G-H

Answer: (A)

Adult inclusion conjunctivitis occurs when the Chlamydia trachomatis strains that commonly infect the genital tract spread to the eye. These particular strains are designated D through K. They invade the conjunctival epithelium and cause a mucopurulent, follicular conjunctivitis that often accompanies mild preauricular lymph node involvement. The reason this set is the best fit is that D–K serotypes are the ones most typically linked to autoinoculation from genital infections, producing the characteristic ocular presentation of inclusion conjunctivitis. In contrast, serotypes A through C are associated with trachoma, which leads to a different, chronic pattern with scarring, and serotypes L1–L3 cause lymphogranuloma venereum, a systemic-genital infection with its own distinct ocular features.