Comparison of Chlamydia trachomatis serovars causing rectal and cervical infections

We used monoclonal antibodies capable of distinguishing serovars of Chlamydia trachomatis to compare 314 cervical isolates with 150 rectal isolates from homosexual men. The isolates were obtained from patients attending a sexually transmitted diseases clinic over a two-year study period. The serovar distribution of cervical and rectal isolates differed significantly. Serovar D/D' was found in 53% of the rectal isolates but in only 18% of cervical isolates (P less than .0001). Serovar E was the predominant serovar in cervical isolates (32%) but was found in only 6% of rectal isolates (P less than .0001). Serovars B, I/I', H, and K were isolated from 2%-7% of cervical specimens but were not found in rectal isolates. There was a significant decline in the proportion of rectal infections caused by serovar D/D' over the study period, and clustering of infections caused by other serovars was observed. Serotyping using monoclonal antibodies provides a powerful tool for investigating the epidemiology of sexually transmitted C. trachomatis infections.