NG-STAR genotypes are associated with MDR in Neisseria gonorrhoeae isolates collected in 2017 in Shanghai

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.

Identification of high-level ceftriaxone-resistant Neisseria gonorrhoeae isolates with diverse penA alleles in Zhejiang, China

OBJECTIVES

The prevalence of ceftriaxone-resistant Neisseria gonorrhoeae poses a significant threat to the effectiveness of gonorrhoea treatment. The aim of the present study was to analyse the characteristics of ceftriaxone-resistant N. gonorrhoeae, with a specific focus on high-level ceftriaxone-resistant strains.

METHODS

A total of 207 strains of N. gonorrhoeae were collected from hospitals in Zhejiang, China, between 2019 and 2020. From this collection, we selected 8 strains of ceftriaxone-resistant N. gonorrhoeae for whole-genome sequencing, genotyping, and molecular profile analysis. For clonal strains (FC428-like), we conducted a phylogenetic analysis to understand their origin and evolutionary path.

RESULTS

Among the selected strains, 5 demonstrated high-level ceftriaxone resistance (MIC 1-2 mg/L). The genotyping results showed that these isolates had a higher diversity of penA alleles than expected. Four isolates had mosaic penA-60.001 allele and the remaining four had different non-mosaic penA alleles. Phylogenetic analysis suggested that the emergence of FC428-like clones containing penA-60.001 may result from further dissemination of different FC428 subclones from different regions of China. The identification of high-level ceftriaxone resistance in non-mosaic penA gonococci, specifically in the ZJ20-3 isolate (penA-21.001) with an MIC of 2 mg/L, is a groundbreaking discovery.

CONCLUSIONS

We present a comprehensive analysis of ceftriaxone-resistant N. gonorrhoeae isolates in Zhejiang, highlighting a significant diversity of penA alleles. The identification of strains exhibiting resistance to ceftriaxone at high levels in our study underscores the potential threat to existing protocols for gonorrhoea treatment. Consequently, we strongly emphasize the urgent need to enhance surveillance initiatives focused on ceftriaxone-resistant N. gonorrhoeae.

Use of genome sequencing to resolve differences in gradient diffusion and agar dilution antimicrobial susceptibility testing performance of Neisseria gonorrhoeae isolates in Alberta, Canada

Agar dilution is the gold standard method for phenotypic antimicrobial susceptibility testing (AST) for Neisseria gonorrhoeae. However, this method is laborious and requires expertise, so laboratories that perform N. gonorrhoeae AST may choose alternative methods such as disk diffusion and gradient diffusion. In this study, we retrospectively compare the performance of gradient diffusion to agar dilution for 2,394 unique N. gonorrhoeae isolates identified in Alberta from 2017 to 2020 against azithromycin, cefixime, ceftriaxone, ciprofloxacin, penicillin, and tetracycline. Genome sequencing was utilized to resolve discrepancies between AST methods, detect antimicrobial resistance markers, and identify trends between error rates and sequence types (STs) of isolates. Over 90% of N. gonorrhoeae isolates were susceptible to azithromycin, cefixime, and ceftriaxone, whereas decreased susceptibility was observed for ciprofloxacin, penicillin, and tetracycline. Categorical (CA) and essential agreement (EA) was poorest between the two methods for penicillin (CA: 86.02%; EA: 77.69%) and tetracycline (CA: 47.22%; EA: 55.96%); however, the low CA was primarily attributed to minor errors. Antimicrobial agents with errors outside of acceptable limits included azithromycin (very major error: 18.42%; major error: 7.73%) and tetracycline (very major error: 6.17%). Genome sequencing on a subset of isolates resolved 30.3% of the azithromycin major errors and confirmed the azithromycin or tetracycline very major errors. Significant associations between certain STs and error types for azithromycin and tetracycline were also identified. Overall, gradient diffusion compared well to agar dilution for cefixime, ceftriaxone, and ciprofloxacin, and genome sequencing was identified as a useful tool to arbitrate discrepant susceptibility testing results between gradient diffusion and agar dilution for N. gonorrhoeae.

Global status of Azithromycin and Erythromycin Resistance Rates in Neisseria gonorrhoeae: A Systematic Review and Meta-analysis

Background: The widespread development of antibiotic resistance or decreased susceptibility in Neisseria gonorrhoeae (NG) infection is a global and significant human public health issue. Objectives: Therefore, this meta-analysis aimed to estimate worldwide resistance rates of NG to the azithromycin and erythromycin according to years, regions, and antimicrobial susceptibility testing (AST). Methods: We systematically searched the published studies in PubMed, Scopus, and Embase from 1988 to 2021. All analyses were conducted using Stata software. Results: The 134 reports included in the meta-analysis were performed in 51 countries and examined 165,172 NG isolates. Most of the included studies were from Asia (50 studies) and Europe (46 studies). In the metadata, the global prevalence over the past 30 years were 6% for azithromycin and 48% for erythromycin. There was substantial change in the prevalence of macrolides NG resistance over time (P <0.01). In this metadata, among 58 countries reporting resistance data for azithromycin, 17 (29.3%) countries reported that >5% of specimens had azithromycin resistance. Conclusions: The implications of this study emphasize the rigorous or improved antimicrobial stewardship, early diagnosis, contact tracing, and enhanced intensive global surveillance system are crucial for control of further spreading of gonococcal emergence of antimicrobial resistance (AMR).

High percentage of the ceftriaxone-resistant Neisseria gonorrhoeae FC428 clone among isolates from a single hospital in Hangzhou, China

OBJECTIVES

Ceftriaxone is currently the last-remaining empirical antimicrobial therapy for treatment of gonorrhoea. However, the high-level ceftriaxone-resistant gonococcal FC428 clone has shown transmission in China in recent years. Therefore, the aim of this study was to analyse ceftriaxone resistance among a collection of recent clinical isolates, with a specific focus on prevalence of the FC428 clone.

METHODS

A total of 70 consecutive gonococcal isolates were collected between May and October 2019 from a single hospital in Hangzhou, China, and analysed for antimicrobial susceptibility by the agar dilution method. STs were determined by PCR and sequences and isolates related to the FC428 clone were further characterized by WGS and phylogenetic analysis.

RESULTS

Ceftriaxone resistance (MIC >0.125 mg/L) was observed in 21 (30%) isolates, while 14 (20%) isolates displayed a ceftriaxone MIC of 0.125 mg/L. Importantly, seven (10%) isolates were related to the gonococcal FC428 clone based on the presence of mosaic penA allele 60.001, displaying identical or closely related STs, and phylogenetic analysis after WGS. These seven isolates displayed high-level ceftriaxone resistance (MIC = 1 mg/L) and all associated gonorrhoea cases resulted in treatment failure because oral cephalosporins were initially prescribed. Subsequent re-treatment with a higher dose (2 g) of IV ceftriaxone appeared to be successful because all patients returning for test-of-cure became culture-negative.

CONCLUSIONS

Here, we report a high percentage of the internationally spreading gonococcal FC428 clone among clinical isolates from a single hospital in Hangzhou, China. A high dose of ceftriaxone is currently the only recommended and effective therapy.

Phylogenomic analysis reveals persistence of gonococcal strains with reduced-susceptibility to extended-spectrum cephalosporins and mosaic penA-34

The recent emergence of strains of Neisseria gonorrhoeae associated with treatment failures to ceftriaxone, the foundation of current treatment options, has raised concerns over a future of untreatable gonorrhea. Current global data on gonococcal strains suggest that several lineages, predominately characterized by mosaic penA alleles, are associated with elevated minimum inhibitory concentrations (MICs) to extended spectrum cephalosporins (ESCs). Here we report on whole genome sequences of 813 N. gonorrhoeae isolates collected through the Gonococcal Isolate Surveillance Project in the United States. Phylogenomic analysis revealed that one persisting lineage (Clade A, multi-locus sequence type [MLST] ST1901) with mosaic penA-34 alleles, contained the majority of isolates with elevated MICs to ESCs. We provide evidence that an ancestor to the globally circulating MLST ST1901 clones potentially emerged around the early to mid-20th century (1944, credibility intervals [CI]: 1935-1953), predating the introduction of cephalosporins, but coinciding with the use of penicillin. Such results indicate that drugs with novel mechanisms of action are needed as these strains continue to persist and disseminate globally.

Typing of Neisseria Gonorrhoeae isolates in Shenzhen, China from 2014-2018 reveals the shift of genotypes associated with antimicrobial resistance

The growing antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a serious global threat to gonococcal therapy. Molecular typing is an ideal tool to reveal the association between specific genotype and resistance phenotype that provides effective data for tracking the transmission of resistant clones of N. gonorrhoeae In our study, we aimed to describe the molecular epidemiology of AMR and the distribution of resistance-associated genotypes in Shenzhen during 2014-2018. In total, 909 isolates were collected from Shenzhen from 2014-2018. Two typing schemes, multilocus sequence typing (MLST) and N. gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR), were performed for all isolates. The distribution of resistance-associated genotypes was described using goeBURST analysis combined with data of logistic regression. Among 909 isolates, ST₈₁₂₃, ST₇₃₆₃, ST₁₉₀₁, ST₇₃₆₅, and ST₇₃₆₀ were most the common MLST sequence types (STs), and ST₃₄₈, ST₂₄₇₃, ST₄₉₇, and ST₁₉₉ were the most prevalent NG-STAR STs. The logistic regression analysis showed that NG-STAR_ST497, MLST_ST7365, and MLST_ST7360 were typically associated with decreased susceptibility to ceftriaxone. Furthermore, the internationally spreading ESC-resistant clone MLST_ST1901 has been prevalent at least in 2014 in Shenzhen and showed a significant increase during 2014-2018. Additionally, MLST_ST7363 owns the potential to become the next internationally spreading ceftriaxone-resistant ST. In conclusions, we performed a comprehensive epidemiological study to explore the correlation between AMR and specific STs, which provided important data for future studies of the molecular epidemiology of AMR in N. gonorrhoeae Besides, these findings provide insight for adjusting surveillance strategies and therapy management in Shenzhen.

Shanghai Neisseria gonorrhoeae Isolates Exhibit Resistance to Extended-Spectrum Cephalosporins and Clonal Distribution

The emergence of Neisseria gonorrhoeae strains with resistance (R) to extended-spectrum cephalosporins (ESCs^R) represents a public health threat of untreatable gonococcal infections. This study was designed to determine the prevalence and molecular mechanisms of ESC^R of Shanghai N. gonorrhoeae isolates. A total of 366 N. gonorrhoeae isolates were collected in 2017 in Shanghai. Susceptibility to ceftriaxone (CRO), cefixime (CFM), azithromycin (AZM), ciprofloxacin (CIP), spectinomycin, penicillin, and tetracycline was determined using the agar dilution method. A subset of 124 isolates was subjected to phylogenetic analysis for nine antimicrobial resistance-associated genes, i.e., penA, porB, ponA, mtrR, 23S rRNA, gyrA, parC, 16S rRNA, and rpsE. Approximately 20.0% of the isolates exhibited CFM^R [minimum inhibitory concentration (MIC) >0.125 mg/L], and 5.5% were CRO^R (MIC > 0.125 mg/L). In total, 72.7% of ESC^R isolates were clonal and associated with mosaic penA 10 and 60 alleles. Non-mosaic penA 18 allele and substitutions of PenA A501T, G542S, and PorB1b G213S/Y were observed in non-clonal ESC^R. Approximately 6.8% of the isolates showed AZM MIC above the epidemiological cutoff (ECOFF, 1 mg/L), were associated with 23S rRNA A2059G mutation, and did not exhibit clonal distribution. Almost all isolates were CIP^R (resistance to ciprofloxacin) and associated with GyrA-91/92 and ParC-85/86/87/88/89/91 alterations. Isolates with ParC S88P substitution were clustered into the ESC^R clade. The Shanghai isolates exhibited a high level of ESC^R and distinct resistant patterns.

Comparative Proteomics of Extended-Spectrum Cephalosporin-Resistant Neisseria gonorrhoeae Isolates Demonstrates Altered Protein Synthesis, Metabolism, Substance Transport, and Membrane Permeability

Neisseria gonorrhoeae isolates exhibit resistance to extended-spectrum cephalosporins (ESCs), the last remaining option for first-line empirical monotherapy. Here, we investigated the proteomic profiles of N. gonorrhoeae clinical isolates with ESC-resistance to support exploration of the antimicrobial resistance mechanisms for N. gonorrhoeae. We used comparative iTRAQ quantitative proteomics to investigate differential protein expression of three ESC-resistant N. gonorrhoeae clinical isolates using N. gonorrhoeae ATCC49226 as a reference strain. The expression of 40 proteins was downregulated and expression of 56 proteins was upregulated in all three ESC-resistant N. gonorrhoeae isolates. Proteins with predicted function of translation, ribosomal structure and biogenesis, as well as components of the Type IV secretory systems, were significantly upregulated. Two differentially expressed proteins of ABC transporters were also reported by other teams in proteomics studies of N. gonorrhoeae isolates under antimicrobial stress conditions. Differentially expressed proteins are involved in energy production and metabolism of carbohydrates and amino acids. Our results indicated that amino acid and carbohydrate metabolism, cell membrane structure, interbacterial DNA transfer, and ribosome components might be involved in mediating ESC-resistance in N. gonorrhoeae. These findings facilitate a better understanding of the mechanisms of ESC-resistance in N. gonorrhoeae and provide useful information for identifying novel targets in the development of antimicrobials against N. gonorrhoeae.