A Novel Method to Assess Antimicrobial Susceptibility in Commensal Oropharyngeal Neisseria-A Pilot Study

Pharyngeal gonococcal infection and the sensitivity of oral gargle samples in comparison to self-collected throat swabs for the detection of N. gonorrhoeae in persons in Tyrol, Austria

PURPOSE

Asymptomatic pharyngeal gonorrhoea could play an important role in transmission and should be screened for in persons at risk. We investigated the sensitivity of oral gargle samples to detect N. gonorrhoea and describe the frequency of infection by anatomical site.

METHODS

From June 2021 to July 2022 persons diagnosed with gonorrhoea in the STI/HIV department were asked to provide self-collected specimens for single-site testing by NAAT from throat (by gargling and swabbing), anorectum, and first-void urine.

RESULTS

104 episodes of gonorrhoea were analysed in 88 individuals. The median age was 33 years, 85 persons (96.5%) were male. The pharynx was the most common site of infection (71 cases, 68.2%); in 26 persons (25.0%) it was the only site of infection. Anorectal infection was detected in 65 cases (62.5%) and urogenital infection in 25 cases (24.0%). In 46 cases (44.2%) infection was detected in more than one anatomical site. Gargling was less sensitive than throat swabbing to detect pharyngeal infection (85.9% versus 97.2%, p = .038), but was preferred by patients. Only 4 of 71 pharyngeal infections (5.6%) were symptomatic; anorectal and urogenital infections were symptomatic in 12.3% and 76.0% of cases, respectively. Culture recovery of N.gonorrhoeae was only possible in 15.8% of throat swabs, but was successful in 61.9% of anorectal and 84.2% of urogenital samples.

CONCLUSIONS

Asymptomatic pharyngeal gonorrhoea is common. Gargle samples should be used only as alternative specimens with inferior sensitivity compared to throat swab samples.

Canary in the Coal Mine: How Resistance Surveillance in Commensals Could Help Curb the Spread of AMR in Pathogenic Neisseria

Antimicrobial resistance (AMR) is widespread within Neisseria gonorrhoeae populations. Recent work has highlighted the importance of commensal Neisseria (cN) as a source of AMR for their pathogenic relatives through horizontal gene transfer (HGT) of AMR alleles, such as mosaic penicillin binding protein 2 (penA), multiple transferable efflux pump (mtr), and DNA gyrase subunit A (gyrA) which impact beta-lactam, azithromycin, and ciprofloxacin susceptibility, respectively. However, nonpathogenic commensal species are rarely characterized. Here, we propose that surveillance of the universally carried commensal Neisseria may play the role of the "canary in the coal mine," and reveal circulating known and novel antimicrobial resistance determinants transferable to pathogenic Neisseria. We summarize the current understanding of commensal Neisseria as an AMR reservoir, and call to increase research on commensal Neisseria species, through expanding established gonococcal surveillance programs to include the collection, isolation, antimicrobial resistance phenotyping, and whole-genome sequencing (WGS) of commensal isolates. This will help combat AMR in the pathogenic Neisseria by: (i) determining the contemporary AMR profile of commensal Neisseria, (ii) correlating AMR phenotypes with known and novel genetic determinants, (iii) qualifying and quantifying horizontal gene transfer (HGT) for AMR determinants, and (iv) expanding commensal Neisseria genomic databases, perhaps leading to the identification of new drug and vaccine targets. The proposed modification to established Neisseria collection protocols could transform our ability to address AMR N. gonorrhoeae, while requiring minor modifications to current surveillance practices. IMPORTANCE Contemporary increases in the prevalence of antimicrobial resistance (AMR) in Neisseria gonorrhoeae populations is a direct threat to global public health and the effective treatment of gonorrhea. Substantial effort and financial support are being spent on identifying resistance mechanisms circulating within the gonococcal population. However, these surveys often overlook a known source of resistance for gonococci-the commensal Neisseria. Commensal Neisseria and pathogenic Neisseria frequently share DNA through horizontal gene transfer, which has played a large role in rendering antibiotic therapies ineffective in pathogenic Neisseria populations. Here, we propose the expansion of established gonococcal surveillance programs to integrate a collection, AMR profiling, and genomic sequencing pipeline for commensal species. This proposed expansion will enhance the field's ability to identify resistance in and from nonpathogenic reservoirs and anticipate AMR trends in pathogenic Neisseria.