Implementation and evaluation of the presto combined qualitative real-time assay for Chlamydia trachomatis and Neisseria gonorrhoeae in Rwanda

ABSTRACT

Background: The Presto combined qualitative real-time assay for Chlamydia trachomatis and Neisseria gonorrhoeae (Presto CT/NG PCR assay) is appealing for developing countries, because it can be used with multiple DNA extraction methods and polymerase chain reaction (PCR) platforms.Objectives: The objective of the study was to implement and evaluate the Presto CT/NG PCR assay at the National Reference Laboratory (NRL) in Kigali, Rwanda, where no real-time PCR assays for the detection of C. trachomatis or N. gonorrhoeae were available.Methods: The Presto CT/NG PCR assay was first evaluated at the Institute of Tropical Medicine (ITM) in Antwerp, Belgium. Next, NRL laboratory technicians were trained to use the assay on their ABI PRISM 7500 real-time PCR instrument and their competencies were assessed prior to trial initiation. During the trial, endocervical swabs were tested at the NRL, with bi-monthly external quality control testing monitored by the ITM. The final NRL results were evaluated against extended gold standard testing at the ITM, consisting of the Abbott m2000 RealTime System with confirmation of positive results by an in-house real-time PCR assay for C. trachomatis or N. gonorrhoeae.Results: Of the 192 samples analysed using the Presto assay at the NRL, 16 samples tested positive for C. trachomatis and 17 tested positive for N. gonorrhoeae; four of these were infected with both. The sensitivity and specificity of the Presto assay were 93.3% (95% confidence interval [CI] 68.1% ­ 99.8%) and 99.4% (95% CI 96.8% ­ 100%) for C. trachomatis and 100% (95% CI 76.8% ­ 100%) and 98.8% (95% CI 95.8% ­ 99.9%) for N. gonorrhoeae.Conclusion: C. trachomatis and N. gonorrhoeae testing with the Presto assay was feasible in Kigali, Rwanda, and good performance was achieved