Introduction The use of nucleic acid amplification tests (NAATs) to diagnose Neisseria gonorrhoeae (Ng) infections has rapidly replaced culture. This complicates performance of test of cure (TOC) to monitor treatment failure. As evidence for the timing of TOC using modern Ng NAATs is highly limited, we assessed the time to Ng-clearance when using modern NAATs.
Methods We included patients attending the STI Clinic Amsterdam from March–October 2014 with anogenital Ng. We collected swabs or urine for RNA-based NAAT (Aptima Combo 2 assay [AC2], Hologic) and DNA-based NAAT (Cobas 4800 NG/CT assay [C4800], Roche). Treatment for Ng was ceftriaxone 500 mg. Upon treatment, patients self-collected daily samples for both NAATs for 28 days, and recorded sexual contact in a diary. After 28 days, patients returned to the clinic with their samples, and we collected final samples for culture and NAAT. Clearance was defined as two consecutive negative results. Reinfection was defined as >2 positive results after clearance, with at least one result positive in both DNA and RNA-based NAAT. A blip was defined as a positive RNA or DNA result after clearance without reinfection.
Results We included 77 patients of whom 62 completed the study. The median number of self-collected samples was 27. Anatomical locations were distributed evenly (urethra: 20, vagina: 21, rectum: 21). 23 (37%) patients had a Chlamydia trachomatis co-infection. All patients cleared Ng during the study and median time to clearance was 2 days (range: 1–9) for both NAATs. 95% of patients cleared before day 6 (AC2) and day 7 (C4800). Reinfection was observed in one patient. Blips occured in 6 (AC2) and 15 (C4800) patients, respectively.
Conclusion With modern RNA- or DNA-based NAATs, a TOC of anogenital gonorrhoea can be performed after 7–9 days. However, intermittent positive test results after clearance occurred in 10–25% of patients.
Disclosure of interest statement This study was funded by the Public Health Service Amsterdam. Aptima products and test kits were provided by Hologic. Roche PCR products and Cobas 4800 test kits were provided by Roche.