Study on vertical transmission of Chlamydia trachomatis using PGR and DNA sequencing

Objective To investigate the vertical transmission rate of Chlamydia tracho matis (CT) in Chongqing, China. Methods Specimens taken from 278 women and from their 79 infants were exami ned by cell culture, polymerase chain reaction (PCR) and DNA sequence analy sis. Chlamydia trachomatis was isolated in McCoy cell culture. CT DNA was e xtracted with a modified NaI method. After cloning, recombinant plasmids we re used for sequence analysis with the dideoxy chain termination method. Results 10.8% (30/278) of the cervical cultures of pregnant women were posi tive for Chlamydia trachomatis, while the positive rate tested by PCR was 1 4.0% (39/278). The vertical transmission rate of Chlamydia trachomatis was 55.0% (11/20). The incidences of conjunctivitis and pneumonia in infants wi th Chlamydia trachomatis positive mothers were 27.3% and 18.2%, respectivel y. DNA sequences of Chlamydia trachomatis isolated from the cervix of a mot her and the nasopharynx of her baby were identical. Conclusion Chlamydia trachomatis infection is quite common in Chongqing, Ch ina. Our report is the first report of CT vertical transmission proved by D NA sequence analysis.