Background Chlamydia trachomatis and Neisseria gonorrhoeae are among the most common causes of sexually transmitted bacterial infections worldwide. Infection with these organisms is mostly asymptomatic, however serious complications are also observed. Screening of the diseases is necessary to identify, treat and control the infection. In this study, we evaluated the performance of the triplex real-time PCR assay with internal control for detection of C. trachomatis and N. gonorrhoeae infections in urine and vaginal swabs.
Methods The performance of TaqMan probe-based triplex real time PCR targeting the cryptic plasmids of C. trachomatis (pCHL1) and N. gonorrhoeae (pJD1) and beta-globin gene as an internal control was assessed using 188 urine specimens and 118 vaginal swabs. The triplex real time PCR was compared with the Roche COBAS AMPLICOR CT/NG assay. The urine specimens were further tested using real-time PCR targeting the N. gonorrhoeae porA pseudogene.
Results For urine specimens, the sensitivity and specificity of the triplex real time PCR were 100% and 97.6%, respectively, for C. trachomatis, and 100% and 95.2%, respectively, for N. gonorrhoeae. For vaginal swabs, the sensitivity and specificity were 100% and 100%, respectively, for C. trachomatis, and 100% and 98.1%, respectively, for N. gonorrhoeae. There were 5 (2.84%) from 176 urine specimens that were negative for cryptic plasmid, but positive for N. gonorrhoeae porA pseudogene.
Conclusion The performance of the triplex real time PCR assay was comparable to that of the Roche COBAS AMPLICOR CT/NG assay. This assay is easy to perform and the results can be achieved in 3–4 hours, including sample preparation. The estimated cost of triplex real time PCR was less than 20 USD. Taken together with using non-invasive urine sampling, this assay is convenient and suitable for epidemiological studies in screening large number of samples.
- Chlamydia trachomatis
- Neisseria gonorrhoeae
- Real-time PCR