Genotyping of Chlamydia trachomatis from a trachoma-endemic village in the Gambia by a nested polymerase chain reaction: identification of strain variants.

Direct amplification of the major outer membrane protein (MOMP) gene by polymerase chain reaction (PCR) was used to identify Chlamydia trachomatis in eye swabs from clinically active cases of endemic trachoma in a Gambian village. Chlamydial DNA was detected in 51% of 96 subjects with clinically active disease and in 5% of 37 clinically negative individuals. The PCR detection was combined with typing, using nested primers to variable sequences (VS) 1, 2, and 4 of the MOMP genes to distinguish between trachoma genotypes A, B, and C, respectively. Genotypes A and B were detected in the village, with some individuals harboring both genotypes within the same eye. DNA sequencing revealed strain variants of both genotypes. Typing of genotype and strain variants is now in progress to study trachoma transmission within the village.