Rapid and simple detection of Chlamydia trachomatis and Neisseria gonorrhoeae using the EasyNAT CT/NG assay based on cross-priming amplification.

Purpose: Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) rank among the most common sexually transmitted pathogens. Rapid screening and detection of these bacteria are essential to reduce sequelae and prevent transmission. This study evaluated the efficacy of the EasyNAT CT/NG assay, which utilizes cross-priming amplification (CPA) technique for the rapid and simultaneous detection of CT and NG in diverse reproductive tract specimens, achieving diagnosis within 30 min.

Methods: The clinical performance of the EasyNAT CT/NG assay in detecting CT and NG was assessed using 198 clinical samples, with results compared to those of conventional in-house Real-Time PCR to determine concordance. Sensitivity was measured using serial dilutions of quantified plasmids and specificity was evaluated by incorporating DNA from 18 common STI pathogens. The assay's suitability as a point-of-care testing (POCT) tool was evaluated with the criteria outlined in Target Product Profiles (TPPs).

Results: The EasyNAT CT/NG assay demonstrated high concordance with Real-Time PCR, with rates of 98.5% for CT and 99.0% for NG. Concordance in urine samples reached 98.6% for CT and 100% for NG, while cervical swabs showed both 97.7% for CT and NG; vaginal and urethral swabs achieved 100% for both pathogens. Among the 198 samples, one urine specimen tested negative for CT by Real-Time PCR but positive by the EasyNAT CT/NG assay, a positive result confirmed by the Cepheid Xpert CT/NG assay. Two cervical swabs, negative for CT and NG by Real-Time PCR, yielded invalid results with the EasyNAT CT/NG assay but were confirmed negative or CT and NG by the Cepheid Xpert CT/NG assay. The EasyNAT CT/NG assay reliably detected CT and NG in turbid specimens, though it may fail with severely hemolytic samples. Its detection limit was 400 copies/mL, with no cross-reactivity observed across 18 other pathogens.

Conclusion: The EasyNAT CT/NG assay offers rapid, sensitive, and specific detection of CT and NG, proving valuable for infection screening and early diagnosis. It shows promise as a rapid POCT method.