To improve the control of Chlamydia trachomatis infection in India, a rapid, specific and costeffective method is much needed. We developed an in-house PCR assay by targeting a unique genomic sequence encoding a protein from the C. trachomatis phospholipase D endonuclease superfamily that produces an amplified fragment of 368 bp. The specificity of the primers was confirmed using genomic DNA from other sexually transmitted disease-causing and related microorganisms and from humans. The assay was highly sensitive and could detect as low as 10 fg C. trachomatis DNA. Clinical evaluation of the in-house-developed PCR was carried out using 450 endocervical specimens that were divided in two groups. In group I (n5274), in-house PCR was evaluated against the direct fluorescence assay. The resolved sensitivity of the in-house PCR method was 97.22 % compared with 88 % for the direct fluorescent antibody assay. In group II (n5176), the in-house PCR was compared with the commercial Roche AMPLICOR MWP CT detection kit. The resolved sensitivity of the in-house PCR assay reported here was 93.1 % and the specificity was 97.46 %, making it a cost-effective alternative for routine diagnosis of genital infection by C. trachomatis. The method should facilitate early detection leading to better prevention and treatment of genital infection in India.
INTRODUCTIONChlamydia trachomatis is one of the most common causative agents of sexually transmitted infections in developing countries including India. Infection with this agent is often asymptomatic (up to 80 % of women and 40 % of men) (Gaydos et al., 2004), making diagnosis and treatment difficult. Undetected genital infections may evolve into complications such as ectopic pregnancy, pelvic inflammatory disease, salpingitis with tubal scarring and infertility in female patients (Black, 1997;Semeniuk et al., 2002). In infected men, arthritis and epididymitis may result in urethral obstruction and decreased fertility. As asymptomatic and untreated patients can spread the disease to their partners, screening of all sexually active adolescents for C. trachomatis infection is recommended (CDC, 2002).Detection methods for C. trachomatis infection include serology, culture method, ELISA, direct fluorescence assay (DFA) and nucleic acid amplification tests (NAATs). Although antigen-based diagnostic assays are as sensitive as the culture method, they show variability due to the methods of sample collection, transport and storage (Mårdh et al., 1981;Mahony & Chernesky, 1985). PCR and ligase chain reaction are more sensitive and specific compared to other diagnostic methods (Black, 1998;Wylie et al., 1998;Semeniuk et al., 2002) and have facilitated the use of less-invasive procedures for detection of asymptomatic C. trachomatis infection in female patients. Currently, several commercial NAAT-based assays such as Gen-Probe APTIMA Combo 2 (AC2), BD Probe Tec ET and Roche AMPLICOR (COBAS and manual) PCRs are available but their high cost prevents their routine use in developing countries. There i...