Non-cultural detection of rectal and pharyngeal gonorrhoea by the Gen-Probe PACE 2 assay

Neisseria gonorrhoeae culture growth rates from asymptomatic individuals with a positive nucleic acid amplification test

Gonorrhoea infections are frequently diagnosed at extragenital locations in asymptomatic individuals and are historically related to poor recovery in culture, which hinders antimicrobial susceptibility testing. The aim of this study was to evaluate recovery rates of N. gonorrhoeae by culture among asymptomatic individuals who tested positive by nucleic acid amplification tests between 2018 and 2019 in Barcelona (Spain). In total, 10,396 individuals were tested for N. gonorrhoeae on first-void urine, rectal, pharyngeal, and/or vaginal swabs depending on sexual behaviour. Overall infection prevalence was 5.5% (95% confidence interval [CI] 5.0 to 5.9%). Seven hundred and ten samples were positive corresponding to 567 individuals. The most common site of infection was the pharynx (71.3%), followed by rectum (23.1%) and genitals (4.7%) (p<0.0001). The N. gonorrhoeae recovery rate in culture, time from positive screening to culture specimen, and inoculation delay were calculated. Recovery rate was 21.7% in pharynx, 66.9% in rectum, and 37.0% in genitals (25.0% vagina, 71.4% urethra) (p<0.0001). Median culture collection time was 1 [0; 3] days, and median inoculation delay was 5.01 [4.99-7.99] hours, with no impact on N. gonorrhoeae recovery, p=0.8367 and p=0.7670, respectively. Despite efforts towards optimizing pre-analytical conditions, the N. gonorrhoeae recovery rate in asymptomatic individuals is unacceptably low (especially for pharynx), representing a problem for monitoring antimicrobial-resistant infections.

Molecular diagnostics for gonorrhoea: implications for antimicrobial resistance and the threat of untreatable gonorrhoea

This Essay from Nicola Low and colleagues discusses the importance of the nucleic acid amplification tests for rapid detection of N. gonorrhoeae and its resistance determinants, as well as the importance of ensuring their rational use, as priorities for controlling both gonorrhoea and antimicrobial resistance.

Please see later in the article for the Editors' Summary

Evaluation of the specificities of five DNA amplification methods for the detection of Neisseria gonorrhoeae

The intragenus specificities of five molecular diagnostic methods for Neisseria gonorrhoeae were determined. Three assays were considered suboptimal. Molecular detection of N. gonorrhoeae from sites where other Neisseria spp. commonly occur or from any site in low-prevalence settings should be confirmed by a test targeting a different genetic locus.