Comparison of plasmid and chromosomal omp1 gene-based PCR and two DNA extraction methods for diagnosing Chlamydia trachomatis in endocervical swab samples

ObjectiveTo evaluate the effectiveness of boiling and proteolytic DNA extraction methods and also to compare the sensitivity of plasmid polymerase chain reaction (PCR) and chromosomal omp1 gene PCR for genital Chlamydia trachomatis swab samples in women.Methods710 cervical swab samples were obtained from women with symptomatic genital infection at 11 gynecology and obstetric clinics located in Ahvaz, Iran. DNA extraction was performed using proteolysis and boiling manners for all samples. Plasmid PCR and chromosomal omp1 gene primary- and seminested-PCR were then performed separately on extracted DNA in boiling and proteolytic methods.ResultsThe prevalence of this infection was 17.6% as determined by plasmid-PCR, 13.2% by omp1-primary PCR and 15.8% by omp1-nested PCR. Sensitivities of boiling and proteolytic extraction-directed PCR were 93.6%, and 68.8%, respectively, which are significantly different (P=0.02). The sign of swab-induced bleeding was significantly found to be the most frequent among women infected with this bacterium (P=0.001) and had a sensitivity of 33.6% and a specificity of 80.5%.ConclusionsIn order to obtain confident statistical results about sensitivity of each manner, in present study these evaluations were carried out for high numbers of samples (710 samples); high number of samples is statistical advantage of this study in comparing with other studies which were performed with low numbers of samples. Using boiling-DNA extraction manner and targeting plasmid sequence for PCR can increase the sensitivity of C. trachomatis diagnosis.