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.

The evaluation of the Allplex™ BV molecular assay for the diagnosis of bacterial vaginosis in symptomatic South African females.

Bacterial vaginosis (BV) is a dysbiosis of vaginal microbiota characterized by a shift from Lactobacillus species predomination to a heterogeneous mixture of anaerobes. We compared the performance characteristics of the Allplex ™ BV molecular assay with the reference test, Nugent score microscopy, for vaginal swab specimens from symptomatic South African women. A total of 213 patients were enrolled, of whom 99 (46.5%) and 132 (62.0%) were diagnosed with BV by Nugent and Allplex™, respectively. The Allplex™ BV assay displayed a sensitivity of 94.9% (95% CI, 88.7%-97.8%) and a specificity of 66.7% (95% CI, 57.6%-74.6%), with an agreement of 79.8% (95% CI, 73.9%-84.7%) (κ = 0.60). Assay design may be enhanced for improved specificity by accounting for differences in healthy and BV-associated vaginal microbiomes among women of different ethnicities.

Demographic and Behavioral Risk Factors Associated with Reduced Susceptibility of Neisseria gonorrhoeae to First-Line Antimicrobials in South African Men with Gonococcal Urethral Discharge.

Neisseria gonorrhoeae is the predominant cause of male urethral discharge in South Africa, and escalating prevalence of gonococcal antimicrobial resistance (AMR) is a major health concern both in-country and globally. We analyzed the demographic, behavioral, and clinical characteristics of 685 men presenting with gonococcal urethral discharge to sentinel surveillance clinics over a 3-year period (2017 to 2019) to determine the burden of factors that are known to be associated with N. gonorrhoeae AMR to first-line therapy (defined as group 1 isolates exhibiting resistance or reduced susceptibility to extended-spectrum cephalosporins or azithromycin). Among 685 men with gonococcal urethral discharge, median age was 28 years (interquartile range [IQR], 24 to 32). Only two men (2/632; 0.3%) self-identified as homosexual; however, on further enquiry, another 16 (2%) confirmed that they had sex with men only. Almost 30% practiced oral sex and were at risk for pharyngeal gonococcal infection. In univariate analysis, male circumcision (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.49 to 0.99) and recent sex outside the country (OR, 1.83; 95% CI, 1.21 to 2.76) were significantly associated with having a category 1 N. gonorrhoeae isolate. In a multivariable model, only sex outside South Africa increased the odds of being infected with a decreased susceptible/resistant N. gonorrhoeae isolate (adjusted odds ratio [aOR], 1.64; 95% CI, 1.05 to 2.55). These findings warrant the intensification of N. gonorrhoeae AMR surveillance among recently arrived migrant and overseas traveler populations, as well as the inclusion of extragenital specimens for N. gonorrhoeae AMR surveillance purposes.

Comparison of gentamicin MICs by agar dilution and Etest for clinical isolates of Neisseria gonorrhoeae.

BACKGROUND: In South Africa, Neisseria gonorrhoeae (NG) is the predominant cause of male urethritis syndrome (MUS). The national MUS treatment guidelines recommend gentamicin as salvage therapy for ceftriaxone treatment failures. We ascertained and compared gentamicin MICs obtained by agar dilution and Etest for clinical isolates of NG. METHODS: Gentamicin MICs for NG culture isolates obtained from 272 MUS cases in 2017 were determined using agar dilution, as per CLSI agar dilution methods, and Etest® (bioMérieux, Marcy-l'Étoile, France). Previously published interpretive criteria were used: MIC ≤4 mg/L, susceptible (S); MIC 8-16 mg/L, intermediately resistant (IR); and MIC ≥32 mg/L, resistant (R). WHO 2008 NG reference strains were used as comparison standards. RESULTS: Gentamicin agar dilution versus Etest MIC results (mg/L) were as follows: MIC50 = 16 versus 4; MIC90 = 16 versus 8; minimum MIC = 4 versus 1; and maximum MIC = 32 versus 16. Interpretive categories for agar dilution versus Etest were as follows: S, 4.4% versus 86.8%; IR, 86.0% versus 13.4%; and R, 9.6% versus 0%. The gentamicin MIC50 by agar dilution was significantly higher than by Etest (sign test P value <0.001); overall MIC agreement was 7.4% [kappa statistic (κ) = -0.014 (95% CI -0.039 to 0.010)]. Correlation with expected MICs for WHO reference strains was consistently better with Etest than with agar dilution. CONCLUSIONS: There was a significant discordance between NG gentamicin MICs by agar dilution versus Etest. NG gentamicin AST methodology must be standardized and interpretive criteria established to optimize the monitoring of susceptibility trends.

Trends in Neisseria gonorrhoeae Antimicrobial Resistance over a Ten-Year Surveillance Period, Johannesburg, South Africa, 2008⁻2017.

BACKGROUND: In South Africa, sexually transmitted infections (STIs) are managed through a syndromic approach at primary healthcare centres (PHCs). Neisseria gonorrhoeae is the predominant cause of male urethritis syndrome. We describe antimicrobial resistance patterns and trends in Neisseria gonorrhoeae during a ten-year surveillance period at a large PHC in Johannesburg. METHODS: Neisseria gonorrhoeae was cultured from genital discharge swab specimens obtained from consenting adult patients presenting at the Alexandra Health Centre in Johannesburg between 2008 and 2017. Isolates were tested for antimicrobial susceptibility by Etest™ (cefixime, ceftriaxone, ciprofloxacin) or agar dilution (penicillin, tetracycline, azithromycin). RESULTS: During the period of surveillance, high-level resistance prevalence increased from 30% to 51% for penicillin (p-value for trend < 0.001), 75% to 83% for tetracycline (p-value for trend = 0.008), and 25% to 69% for ciprofloxacin (p-value for trend < 0.001). Analysis did not reveal high-level resistance to spectinomycin or a minimum inhibitory concentration (MIC) creep for extended-spectrum cephalosporins, and the prevalence of intermediate-resistance to azithromycin was less than 5%. CONCLUSIONS: High prevalence resistance to penicillin, tetracycline, and ciprofloxacin in N. gonorrhoeae obviates their use in future national treatment algorithms for genital discharge. It is essential to continue monitoring for emerging resistance to currently recommended antimicrobial therapy in this rapidly evolving pathogen.

Antimicrobial susceptibility of organisms causing community-acquired urinary tract infections in Gauteng Province, South Africa.

BACKGROUND: Patients with community-acquired urinary tract infections (UTIs) frequently present to healthcare facilities in South Africa (SA). AIM: To provide information on UTI aetiology and antimicrobial susceptibility of pathogens. METHODS: We recruited women with UTI-related symptoms, who tested positive for ≥2 urine dipstick criteria (proteinuria, blood, leucocytes or nitrites) at 1 public and 5 private primary healthcare facilities in 2011. Demographic and clinical data were recorded and mid-stream urine (MSU) specimens were cultured. UTI pathogens were Gram-stained and identified to species level. Etest-based antimicrobial susceptibility testing was performed for amoxicillin/clavulanic acid, cefixime, cefuroxime, ciprofloxacin, fosfomycin, levofloxacin, nitrofurantoin, norfloxacin and trimethoprim/sulphamethoxazole. RESULTS: Of the 460 women recruited, 425 MSU samples were processed and 204 UTI pathogens were identified in 201 samples. Most pathogens were Gram-negative bacilli (GNB) (182; 89.2%) and 22 (10.8%) were Gram-positive cocci (GPC). Escherichia coli was the most frequent GNB (160; 79.6%), while Enterococcus faecalis was the predominant GPC (8; 4.0%). The UTI pathogens had similar susceptibility profiles for fosfomycin (95.5%; 95% confidence interval (CI) 92.6 - 98.4), the 3 fluoroquinolones (94.1%; 95% CI 90.8 - 97.4), nitrofurantoin (91.7%; 95% CI 87.8 - 95.6), cefuroxime (90.1%; 95% CI 86.0 - 94.3) and cefixime (88.2%; 95% CI 83.7 - 92.6). UTI pathogens were less susceptible to amoxicillin/clavulanic acid (82.8%; 95% CI 77.5 - 88.0) when compared with fluoroquinolones and fosfomycin. Trimethoprim/ sulphamethoxazole was the least efficacious antimicrobial agent (44.3% susceptible; 95% CI 37.4 - 51.2). CONCLUSION: This study provides relevant data for the empirical treatment of community-acquired UTIs in SA.

Phenotypic and genetic characterization of the first two cases of extended-spectrum-cephalosporin-resistant Neisseria gonorrhoeae infection in South Africa and association with cefixime treatment failure.

OBJECTIVES: To describe the phenotypic and genetic characteristics of the first two cases of extended-spectrum cephalosporin (ESC)-resistant Neisseria gonorrhoeae in South Africa, one of which was associated with verified cefixime treatment failure. PATIENTS AND METHODS: Two ESC-resistant N. gonorrhoeae isolates were cultured from the urethral discharge of two men who have sex with men (MSM). One man reported a persistent urethral discharge that had failed to respond to previous therapy with oral cefixime. Agar dilution MICs were determined for eight antibiotics. ß-Lactam-associated resistance mutations were identified through PCR-based amplification and sequencing for several key genes: penA, mtrR and its promoter, porB1b (penB), ponA and pilQ. For molecular epidemiological characterization, full-length porB gene sequencing, N. gonorrhoeae multiantigen sequence typing (NG-MAST) and multilocus sequence typing (MLST) were performed. RESULTS: Both isolates were resistant to cefixime, ciprofloxacin, penicillin and tetracycline and intermediate/resistant to azithromycin, but susceptible to ceftriaxone, gentamicin and spectinomycin. Both isolates had the type XXXIV penA mosaic allele in addition to previously described resistance mutations in the mtrR promoter (A deletion), porB1b (penB) (G101K and A102N) and ponA1 (L421P). Both isolates had an identical NG-MAST sequence type (ST4822) and MLST sequence type (ST1901). CONCLUSIONS: Both isolates were resistant to cefixime and possessed a number of identical mutations in key genes contributing to ESC resistance in N. gonorrhoeae. The two isolates contained the type XXXIV penA mosaic allele and belonged to a successful international MSM-linked multidrug-resistant gonococcal clone (MLST ST1901) associated with several cefixime treatment failures in Europe and North America.

Plasmid-mediated penicillin and tetracycline resistance among Neisseria gonorrhoeae isolates in South Africa: prevalence, detection and typing using a novel molecular assay.

BACKGROUND: To detect and type plasmids responsible for penicillin and tetracycline resistance in Neisseria gonorrhoeae isolates using a novel duplex polymerase chain reaction (PCR) assay. METHODS: A duplex PCR assay, to detect and type penicillinase-producing N. gonorrhoeae (PPNG), and plasmid-mediated tetracycline resistant N. gonorrhoeae (TRNG), was developed on the basis of published single assays. Gonococcal Isolate Surveillance Project control strains were used in assay development and then 209 consecutive N. gonorrhoeae isolates, collected from men with urethral discharge in 2008, were tested. Controls included Asia, Africa, and Toronto ß-lactamase plasmids, as well as American and Dutch TRNG plasmids. PCR amplicons were detected using an Agilent 2100 Bioanalyzer. Minimum inhibitory concentrations (MIC) were determined with E tests. Penicillinase production was detected using Nitrocefin solution. RESULTS: Among 209 gonococcal isolates, 54 (25.8%) PPNG and 154 (73.3%) TRNG were detected. The MIC50 and MIC90 values were determined for penicillin (0.19 and 32 mg/L) and tetracycline (6 and 16 mg/L). The assay detected the Africa-type (35.2%), the Toronto-type (44.4%), and a new type (20.3%) of ß-lactamase plasmid. The American-type TRNG plasmid was 3-fold more frequent as compared with the Dutch-type. Although there was no overall association between the detection of PPNG and TRNG plasmids, only American type TRNG contained ß-lactamase-encoding plasmids (P < 0.0001). CONCLUSIONS: The prevalence of plasmid-mediated resistance to tetracycline, and to a lesser extent penicillin, is high and neither drug is likely to have any future role in the treatment of gonorrhoea in South Africa. A novel ß-lactamase plasmid was detected during the study and requires further characterization.