ABSTRACT
OBJECTIVES: This study aimed to validate and implement a rapid screening assay for molecular detection of the penA-60 allele that is associated with ceftriaxone resistance in Neisseria gonorrhoeae for use on both isolate lysates and clinical specimen DNA extracts. METHODS: A N.â¯gonorrhoeae penA real-time (RT)-PCR was adapted to include a species-specific pap confirmation target and a commercially available internal control to monitor for PCR inhibition.The modified assay was validated using N.â¯gonorrhoeae-positive (n=24) and N.â¯gonorrhoeae-negative (n=42) clinical specimens and isolate lysates. The panel included seven samples with resistance conferred by penA alleles targeted by the assay and four samples with different penA alleles. The feasibility of using the penA RT-PCR for molecular surveillance was assessed using clinical specimens from 54 individuals attending a London sexual health clinic who also had a N.â¯gonorrhoeae isolate included in the 2020 Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP). RESULTS: The assay correctly identified N.â¯gonorrhoeae specimens (n=7) with penA-60/64 alleles targeted by the assay. No penA false negatives/positives were detected, giving the penA target of the assay a sensitivity, specificity, positive and negative predicted values (PPV, NPV) of 100% (95% CIs; sensitivity; 56.1-100%, specificity; 93.6-100%, PPV; 56.1-100%, NPV; 93.6-100%).No cross-reactivity with other Neisseria species or other urogenital pathogens was detected. The N.â¯gonorrhoeae target (pap) was detected in 73 out of 78 of the N.â¯gonorrhoeae-positive specimens, resulting in 92.6% sensitivity (95% CI 83.0% to 97.3%), 100% specificity (95% CI 75.9% to 100%) and PPV, and a NPV of 89.4% (95% CI 52.5% to 90.9%). No penA-59/60/64 alleles were detected within the clinical specimens from the GRASP 2020 feasibility molecular surveillance study (n=54 individuals). CONCLUSION: The implementation of this PCR assay for patient management, public health and surveillance purposes enables the rapid detection of gonococcal ceftriaxone resistance conferred by the most widely circulating penA alleles.
ABSTRACT
BACKGROUND: Antimicrobial resistance in Neisseria gonorrhoeae is a global public health concern. Tetracycline resistance (TetR) increased from 39.4% to 75.2% between 2016 and 2021 in N. gonorrhoeae isolates collected through national surveillance in England, despite the absence of use of tetracyclines for the treatment of gonorrhoea. OBJECTIVES: We investigated whether there was correlation between bacterial sexually transmitted infection (STI) tests performed and treatment with antimicrobials, with increased TetR in N. gonorrhoeae. METHODS: We examined correlations between bacterial STI tests, antimicrobial treatment and TetR in N. gonorrhoeae, using national surveillance data from three large sexual health services (SHS) in London during 2016-20. Doxycycline prescribing data and antibiograms of a non-STI pathogen from distinct patient groups (sexual health, obstetric and paediatric), at a large London hospital, were analysed to identify if doxycycline use in SHS was associated with resistance in a non-STI organism. RESULTS: A substantial increase in TetR was observed, particularly in isolates from gay, bisexual and other MSM (GBMSM). Strong positive correlations were observed exclusively in GBMSM between N. gonorrhoeae TetR and both bacterial STI tests (râ=â0.97, Pâ=â0.01) and antimicrobial treatment (râ=â0.87, Pâ=â0.05). Doxycycline prescribing increased dramatically during the study period in SHS. Prevalence of TetR in Staphylococcus aureus was higher in isolates sourced from SHS attendees than those from other settings. CONCLUSIONS: Frequent screening of GBMSM at higher risk of STIs, such as those on pre-exposure prophylaxis (PrEP) leading to/and increased use of doxycycline for the treatment of diagnosed infections, may account for the increase in TetR in N. gonorrhoeae.
