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

Abstract

Objective: To investigate the vertical transmission rate of Chlamydia trachomatis (CT) in Chongqing, China.

Methods: Specimens taken from 278 women and from their 79 infants were examined by cell culture, polymerase chain reaction (PCR) and DNA sequence analysis. Chlamydia trachomatis was isolated in McCoy cell culture. CT DNA was extracted with a modified Nal method. After cloning, recombinant plasmids were used for sequence analysis with the dideoxy chain termination method.

Results: 10.8% (30/278) of the cervical cultures of pregnant women were positive for Chlamydia trachomatis, while the positive rate tested by PCR was 14.0% (39/278). The vertical transmission rate of Chlamydia trachomatis was 55.0% (11/20). The incidences of conjunctivitis and pneumonia in infants with Chlamydia trachomatis positive mothers were 27.3% and 18.2%, respectively. DNA sequences of Chlamydia trachomatis isolated from the cervix of a mother and the nasopharynx of her baby were identical.

Conclusion: Chlamydia trachomatis infection is quite common in Chongqing, China. Our report is the first report of CT vertical transmission proved by DNA sequence analysis.