Demographic and behavioural risk factors associated with reduced susceptibility of Neisseria gonorrhoeae to first-line antimicrobials in South African men with gonococcal urethral discharge

Emergence of high-level azithromycin-resistant Neisseria gonorrhoeae causing male urethritis in Johannesburg, South Africa, 2021

BACKGROUND

In South Africa, Neisseria gonorrhoeae , which is the predominant cause of male urethritis, is treated syndromically using dual ceftriaxone and azithromycin therapy. We determined antimicrobial susceptibilities of N. gonorrhoeae isolates from urethral discharge specimens, and genetically characterised those with elevated minimum inhibitory concentrations (MICs) for first-line antimicrobials.

METHODS

Routine antimicrobial susceptibility testing (AST) of N. gonorrhoeae isolates included E-test for ceftriaxone, cefixime and gentamicin and agar dilution for azithromycin and spectinomycin. Neisseria gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR) was performed for isolates with elevated MICs to identify antimicrobial resistance (AMR) determinants, and Neisseria gonorrhoeae Multi-Antigen Sequence Typing (NG-MAST) was used to determine strain relatedness.

RESULTS

N. gonorrhoeae was cultured from urethral discharge swab specimens obtained from 196 of 238 (82.4%) men presenting to a primary healthcare facility in Johannesburg in 2021. All viable isolates were susceptible to extended-spectrum cephalosporins. Four isolates had high azithromycin MICs ranging from 32mg/L to >256mg/L and grouped into two novel NG-MAST and NG-STAR groups. Two isolates from Group 1 (NG-MAST ST20366, NG-STAR ST4322) contained mutated mtrR (G45D) and 23S rRNA (A2059G) alleles, while the two isolates from Group 2 (NG-MAST ST20367, NG-STAR ST4323) had different mutations in mtrR (A39T) and 23S rRNA (C2611T).

CONCLUSIONS

We report the first cases of high-level azithromycin resistance in N. gonorrhoeae from South Africa. Continued AMR surveillance is critical to detect increasing azithromycin resistance prevalence in N. gonorrhoeae , which may justify future modifications to the STI syndromic management guidelines.

Etiological Surveillance of Male Urethritis Syndrome in South Africa: 2019 to 2020

BACKGROUND

In South Africa, male urethritis syndrome (MUS) is the most common sexually transmitted infection (STI) syndrome in men. We determined the distribution of STI etiologies and the susceptibility profiles of Neisseria gonorrhoeae isolates from men presenting with MUS to 3 sentinel surveillance health care facilities. Secondary objectives were to determine the seroprevalence of coinfections (HIV, syphilis, herpes simplex virus 2).

METHODS

Consecutive, consenting men with symptomatic urethral discharge were enrolled between January 1, 2019, and December 31, 2020. Genital discharge swab and blood specimens were collected and transported to a central STI reference laboratory in Johannesburg, South Africa.

RESULTS

Among 769 men enrolled, N. gonorrhoeae was the commonest cause of MUS (674 [87.8%]; 95% confidence interval [CI], 85.2%-89.9%), followed by Chlamydia trachomatis (161 [21.0%]; 95% CI, 18.2%-24.0%). Of 542 cultivable N. gonorrhoeae isolates, all were susceptible to ceftriaxone (modal minimum inhibitory concentration, 0.004 mg/L) and azithromycin (modal minimum inhibitory concentration, 0.128 mg/L). Seroprevalence rates of HIV, syphilis, and HSV-2 were 21.4% (95% CI, 18.5%-24.5%), 2.3%, and 50.1%, respectively. Condom use at last sexual encounter was reported by only 7%, less than 50% had been medically circumcised, and only 66.7% (58 of 87) who self-reported an HIV-positive status were adherent on antiretroviral drugs.

CONCLUSIONS

Neisseria gonorrhoeae and C. trachomatis were the predominant causes of MUS. Currently recommended dual ceftriaxone and azithromycin therapy are appropriate for MUS syndromic management; however, surveillance must be maintained to timeously detect emerging and increasing gonococcal resistance. Clinic-based interventions must be intensified in men seeing sexual health care to reduce the community transmission and burden of STI and HIV.