Increasing Resistance to Azithromycin in Neisseria gonorrhoeae in Eastern Chinese Cities: Resistance Mechanisms and Genetic Diversity among Isolates from Nanjing

Penicillin-Binding Protein Occupancy Dataset for 18 β-Lactams and 4 β-Lactamase Inhibitors in Neisseria gonorrhoeae

The lack of effective first-line antibiotic treatments against Neisseria gonorrhoeae, and the worldwide dissemination of resistant strains, are the main drivers of a worsening global health crisis. β-lactam antibiotics have been the backbone of therapeutic armamentarium against gonococci. However, we are lacking critical insights to design rationally optimized therapies. In the present work, we generated the first PBP-binding data set on 18 currently available and clinically relevant β-lactams and 4 β-lactamase inhibitors in two N. gonorrhoeae ATCC type collection strains, 19424 and 49226 (PBP2 type XXII and A39T change in mtrR). PBP binding (IC50) was determined via the Bocillin FL binding assay in isolated membrane preparations. Three clusters of differential PBP IC50s were identified and were mostly consistent across both strains, but with quantitative differences. Carbapenems were coselective for PBP2 and PBP3 (0.01 to 0.03 mg/L). Third- and fourth-generation cephalosporins cefixime, cefotaxime, ceftazidime, cefepime, and ceftriaxone showed the lowest IC50 values for PBP2 (0.01 mg/L), whereas cefoxitin, ceftaroline, and ceftolozane required higher concentrations (0.04 to >2 mg/L). Aztreonam was selective for PBP2 in both strains (0.03 to 0.07 mg/L); amdinocillin bound this PBP at higher concentrations (1.33 to 2.94 mg/L). Penicillins specifically targeted PBP2 in strain ATCC 19424 (0.02 to 0.19 mg/L) and showed limited inhibition in strain ATCC 49226 (0.01 to >2 mg/L). Preferential PBP2 binding was observed by β-lactam-based β-lactamase inhibitors sulbactam and tazobactam (1.07 to 6.02 mg/L); meanwhile, diazabicyclooctane inhibitors relebactam and avibactam were selective for PBP3 (1.27 to 5.40 mg/L). This data set will set the bar for future studies that will help the rational use and translational development of antibiotics against multidrug-resistant (MDR) N. gonorrhoeae. IMPORTANCE The manuscript represents the first N. gonorrhoeae PBP-binding data set for 22 chemically different drugs in two type strains with different genetic background. We have identified three clusters of drugs according to their PBP binding IC50s and highlighted the binding differences across the two strains studied. With the currently available genomic information and the PBP-binding data, we have been able to correlate the target attainment differences and the mutations that affect the drug uptake with the MIC changes. The results of the current work will allow us to develop molecular tools of great practical use for the study and the design of new rationally designed therapies capable of combating the growing MDR gonococci threat.

Genetic characteristics of azithromycin-resistant Neisseria gonorrhoeae collected in Hyogo, Japan during 2015-2019

Introduction. Azithromycin (AZM) is a therapeutic drug for sexually transmitted infections and is used for Neisseria gonorrhoeae when first- and second-line drugs are not available. Recently, the susceptibility of N. gonorrhoeae against AZM has been decreasing worldwide.Hypothesis/Gap Statement. Azithromycin-resistance (AZM-R) rates among N. gonorrhoeae in Japan are increasing, and the gene mutations and epidemiological characteristics of AZM-R in N. gonorrhoeae have not been fully investigated.Aim. We determined the susceptibility to AZM and its correlation with genetic characteristics of N. gonorrhoeae.Methodology. We investigated the susceptibility to AZM and genetic characteristics of N. gonorrhoeae. Mutations in domain V of the 23S rRNA gene and mtrR were examined in 93 isolates, including 13 AZM-R isolates. Spread and clonality were examined using sequence types (STs) of multi-antigen sequence typing for N. gonorrhoeae (NG-MAST), and whole genome analysis (WGA) to identify single nucleotide polymorphisms.Results. The number of AZM-R isolates increased gradually from 2015 to 2019 in Hyogo (P=0.008). C2599T mutations in 23S rRNA significantly increased in AZM-R isolates (P<0.001). NG-MAST ST4207 and ST6762 were frequently detected in AZM-R isolates, and they had higher MICs to AZM from 6 to 24 µg/ml. The phylogenic tree-based WGA showed that all isolates with ST4207 were contained in the same clade, and isolates with ST6762 were divided into two clades, AZM-S isolates and AZM-R isolates, which were different from the cluster containing ST1407.Conclusion. Our study showed yearly increases in AZM-R rates in N. gonorrhoeae. NG-MAST ST4207 and ST6762 were not detected in our previous study in 2015 and were frequently identified in isolates with higher MICs to AZM. WGA confirmed that isolates with these STs are closely related to each other. Continued surveillance is needed to detect the emergence and confirm the spread of NG-MAST ST4207 and ST6762.

Systemic and Mucosal Concentrations of Nine Cytokines Among Individuals with Neisseria gonorrhoeae infection in Nairobi Kenya

Introduction: The human-restricted sexually transmitted Neisseria gonorrhoeae (NG) has been shown to modulate the immune response against it and consequently the cytokines produced. The levels of cytokines in NG infection in the African population have not been well described. We aimed to quantify the systemic and mucosal cytokines in NG infection. Methods: This was a comparative cross-sectional study. Levels of nine cytokines (IL-1β, IL-2, IL-4, 1L-6, 1L-10, 1L-12p70, IL-17A, TNF-α and INF-γ) were measured from plasma and genital samples (urethral swabs in men and cervicovaginal lavage in women) from 61 Neisseria gonorrhoeae infected individuals seeking treatment for sexually transmitted infections (STIs) at Casino Health Centre in Nairobi, Kenya. A comparative group of 61 NG-uninfected individuals, seeking treatment at the same facility but with laboratory-confirmed negative Neisseria gonorrhoeae, Chlamydia trachomatis (CT), Mycoplasma genitalium (MG) and Trichomonas vaginalis(TV) was also included. The Mann-Whitney U test was used to compare the cytokine levels between NG-infected and uninfected individuals. Data was analyzed using STATA ver. 15.1. Results: Overall, systemic IL-6, TNF-α and IL-10 were elevated while genital IL-10 and TNF-α were lower in NG positive participants. On subgroup analysis by sex, the levels of genital IL-1β and IL-6 and systemic IL-6 were elevated in NG-infected men. None of the genital cytokines were elevated in NG-infected women, while all systemic cytokines, except INF-γ, were elevated in NG-infected women. Conclusions: Neisseria gonorrhoeae induced the production of different cytokines in men and women, with men having a pro-inflammatory genital response. These differences should be taken into consideration during development of various interventions e.g. vaccine development.

The Accuracy of Molecular Detection Targeting the Mutation C2611T for Detecting Moderate-Level Azithromycin Resistance in Neisseria gonorrhoeae: A Systematic Review and Meta-Analysis

BACKGROUND

Neisseria gonorrhoeae (N. gonorrhoeae) is now recognized as a commonly reported sexually transmitted pathogen, and the increasing drug resistance of N. gonorrhoeae has become a serious public health problem. The accuracy of molecular detection for detecting moderate-level azithromycin resistance is not well-established. We summarized the data from studies of the N. gonorrhoeae 23S rRNA mutation at position 2611 with azithromycin resistance to determine the relationship between the mutation and resistance.

METHODS AND FINDINGS

In this systematic review and meta-analysis, two researchers independently searched six databases for studies with data for the azithromycin minimum inhibitory concentrations (MICs) and the 23S rRNA mutation C2611T of each N. gonorrhoeae isolate. Since the breakpoint of moderate-level resistance to azithromycin (ML-AzmR) was not determined, we divided the moderate level into two groups according to the range of MICs (moderate resistance limited to 2-128 mg/L or 4-128 mg/L) for data extraction. A random-effects model was used to calculate the pooled sensitivity rate, the specificity rate, the pooled positive likelihood ratio (PLR), the negative likelihood ratio (NLR), and the diagnostic odds ratio (DOR). Meta-regression analyses by detection method, isolates sampling (a random sample or not), location, and sample size were performed to explore the possible causes of heterogeneity. The potential publication bias of the included studies was conducted by the Deeks' test. We included 20 studies in our study: 20 studies have data of N. gonorrhoeae with MICs between 2 and 128 mg/L with mutation or without mutation at position 2611(4759 samples), and 14 studies have data of N. gonorrhoeae with MICs between 4 and 128 mg/L (3367 samples). In the group with the moderate level of 2-128 mg/L, the pooled sensitivity rate of the molecular assays was determined to be 71.9% (95% CI, 67.6-74%), the pooled specificity rate was 98.7% (95% CI, 98.2-99.0%), and the DOR ranged from 55.0 to 351.3 (mean, 139.1). In the 4-128 mg/L group, the pooled sensitivity rate was 91.9% (95% CI, 88.9-94.2%), the pooled specificity rate was 95.9% (95% CI, 95.1-96.6%), and the DOR ranged from 41.9 to 364.1 (mean, 123.6).

CONCLUSION

Through this meta-analysis, we found that the C2611T mutation of 23S rRNA is valuable for the molecular diagnostic of moderate-level azithromycin resistance (ML-AzmR) in N. gonorrhoeae, especially when the moderate level is set at 4-128 mg/L. This rapid molecular detection method can be used for the rapid identification of ML-AzmR isolates in the clinic.

Emergence and dissemination of three mild outbreaks of Neisseria gonorrhoeae with high-level resistance to azithromycin in Barcelona, 2016-18

BACKGROUND

Neisseria gonorrhoeae (NG) isolates with high-level azithromycin resistance (HL-AziR) have emerged worldwide in recent decades, threatening the sustainability of current dual-antimicrobial therapy.

OBJECTIVES

This study aimed to characterize the first 16 NG isolates with HL-AziR in Barcelona between 2016 and 2018.

METHODS

WGS was used to identify the mechanisms of antimicrobial resistance, to establish the MLST ST, NG multiantigen sequence typing (NG-MAST) ST and NG sequence typing for antimicrobial resistance (NG-STAR) ST and to identify the clonal relatedness of the isolates with other closely related NG previously described in other countries based on a whole-genome SNP analysis approach. The sociodemographic characteristics of the patients included in the study were collected by comprehensive review of their medical records.

RESULTS

Twelve out of 16 HL-AziR isolates belonged to the MLST ST7823/NG-MAST ST5309 genotype and 4 to MLST ST9363/NG-MAST ST3935. All presented the A2059G mutation in all four alleles of the 23S rRNA gene. MLST ST7823/NG-MAST ST5309 isolates were only identified in men who have sex with women and MLST ST9363/NG-MAST ST3935 were found in MSM. Phylogenomic analysis revealed the presence of three transmission clusters of three different NG strains independently associated with sexual behaviour.

CONCLUSIONS

Our findings support the first appearance of three mild outbreaks of NG with HL-AziR in Spain. These results highlight the continuous capacity of NG to develop antimicrobial resistance and spread among sexual networks. The enhanced resolution of WGS provides valuable information for outbreak investigation, complementing the implementation of public health measures focused on the prevention and dissemination of MDR NG.

Utility of MALDI-TOF MS for differentiation of Neisseria gonorrhoeae isolates with dissimilar azithromycin susceptibility profiles

BACKGROUND

Antibiotic-resistant gonorrhoea has been a chronic public health burden since the mid-1930s. Recent emergence of isolates resistant to the current recommended antibiotics for gonorrhoea further magnifies the threat of untreatable gonorrhoea. The lack of new, effective antibiotics highlights the need for better understanding of the population structure of Neisseria gonorrhoeae in order to provide greater insight on how to curtail the spread of antimicrobial-resistant N. gonorrhoeae.

OBJECTIVES

To explore a potential application of MALDI-TOF MS to differentiate N. gonorrhoeae displaying different levels of susceptibility to the antibiotic azithromycin.

METHODS

We conducted MALDI-TOF MS using the Bruker Biotyper on 392 N. gonorrhoeae isolates collected through the Gonococcal Isolate Surveillance Project (GISP) and/or the Strengthening the United States Response to Resistant Gonorrhea (SURRG) project. The MALDI-TOF MS spectra were visually analysed to assess the presence of distinctive peak(s). Statistical analysis was performed to assess the relationship between gonococcal isolates with the distinct protein peak and antibiotic susceptibility.

RESULTS

In this study, we were able to differentiate N. gonorrhoeae isolates into two distinct subpopulations using MALDI-TOF MS. Isolates were distinguished by the presence or absence of a spectral peak at 11 300 Da. Notably, these two groups exhibited different levels of susceptibility to azithromycin.

CONCLUSIONS

We have shown that in addition to its ability to identify N. gonorrhoeae, MALDI-TOF MS could also be used to differentiate gonococcal isolates with different levels of susceptibility to azithromycin.

Evidence of Horizontal Gene Transfer of 50S Ribosomal Genes rplB, rplD, and rplY in Neisseria gonorrhoeae

Horizontal gene transfer (HGT) in the penA and multidrug efflux pump genes has been shown to play a key role in the genesis of antimicrobial resistance in Neisseria gonorrhoeae. In this study, we evaluated if there was evidence of HGT in the genes coding for the ribosomal proteins in the Neisseria genus. We did this in a collection of 11,659 isolates of Neisseria, including N. gonorrhoeae and commensal Neisseria species (N. cinerea, N. elongata, N. flavescens, N. mucosa, N. polysaccharea, and N. subflava). Comparative genomic analyses identified HGT events in three genes: rplB, rplD, and rplY coding for ribosomal proteins L2, L4 and L25, respectively. Recombination events were predicted in N. gonorrhoeae and N. cinerea, N. subflava, and N. lactamica were identified as likely progenitors. In total, 2,337, 2,355, and 1,127 isolates possessed L2, L4, and L25 HGT events. Strong associations were found between HGT in L2/L4 and the C2597T 23S rRNA mutation that confers reduced susceptibility to macrolides. Whilst previous studies have found evidence of HGT of entire genes coding for ribosomal proteins in other bacterial species, this is the first study to find evidence of HGT-mediated chimerization of ribosomal proteins.

Retrospective Analysis of Drug Sensitivity of Neisseria gonorrhoeae in Teaching Hospitals of South China

The aim of this study was retrospective analysis of drug sensitivity of Neisseria gonorrhoeae in two teaching hospitals of South China. A total of 304 Neisseria gonorrhoeae isolates obtained from patients in South China from 2016 to 2020 were evaluated. The MICs of penicillin, cefuroxime, ceftriaxone (CRO), cefepime, ciprofloxacin, ceftazidime and azithromycin (AZM) against the isolates were determined by the agar dilution method. Then, Neisseria gonorrhoeae isolates were categorized into sensitive, moderately sensitive and resistant according to MICs. Also, β-lactamases were detected by enzyme linked immunosorbent assay (ELISA). Ureaplasma urealyticum and Mycoplasma hominis were determined by culture in liquid medium, and Chlamydia was detected by rapid antigen test. The result showed there was 50.99%, 20.72%, 9.87%, 14.47%, 86.84%, 7.57%, 6.91%, 11.18% resistance to penicillin, cefuroxime, ceftriaxone, cefepime, ciprofloxacin, ceftazidime and azithromycin, respectively. Also, β-lactamase positivity was 53.29% and Chlamydia antigen positivity was 20.07%. Ureaplasma urealyticum and Mycoplasma hominis positivity was 11.84% and 6.25%, respectively. From 2016 to 2020, the resistant rate of ceftriaxone and azithromycin gradually increased. In conclusion, Southern China is among the area reporting gonococci with high-level resistance to AZM and CRO, so N. gonorrhoeae culture and drug sensitivity test will be vital for monitoring trends in antimicrobial resistance.

Atypical Mutation in Neisseria gonorrhoeae 23S rRNA Associated with High-Level Azithromycin Resistance

A2059G mutation in the 23S rRNA gene is the only reported mechanism conferring high-level azithromycin resistance (HL-AZMR) in Neisseria gonorrhoeae Through U.S. gonococcal antimicrobial resistance surveillance projects, we identified four HL-AZMR gonococcal isolates lacking this mutational genotype. Genetic analysis revealed an A2058G mutation of 23S rRNA alleles in all four isolates. In vitro selected gonococcal strains with homozygous A2058G recapitulated the HL-AZMR phenotype. Taken together, we postulate that the A2058G mutation confers HL-AZMR in N. gonorrhoeae.

A Novel Platform Using RNA Signatures To Accelerate Antimicrobial Susceptibility Testing in Neisseria gonorrhoeae

The rise of antimicrobial-resistant pathogens can be attributed to the lack of a rapid pathogen identification (ID) or antimicrobial susceptibility testing (AST), resulting in delayed therapeutic decisions at the point of care. Gonorrhea is usually empirically treated, with no AST results available before treatment, thus contributing to the rapid rise in drug resistance. Here, we present a rapid AST platform using RNA signatures for Neisseria gonorrhoeae Transcriptome sequencing (RNA-seq) followed by bioinformatic tools was applied to explore potential markers in the transcriptome profile of N. gonorrhoeae upon minutes of azithromycin exposure. Validation of candidate markers using quantitative real-time PCR (qRT-PCR) showed that two markers (arsR [NGO1562] and rpsO) can deliver accurate AST results across 14 tested isolates. Further validation of our susceptibility threshold in comparison to MIC across 64 more isolates confirmed the reliability of our platform. Our RNA markers combined with emerging molecular point-of-care systems has the potential to greatly accelerate both ID and AST to inform treatment.

Increased power from conditional bacterial genome-wide association identifies macrolide resistance mutations in Neisseria gonorrhoeae

The emergence of resistance to azithromycin complicates treatment of Neisseria gonorrhoeae, the etiologic agent of gonorrhea. Substantial azithromycin resistance remains unexplained after accounting for known resistance mutations. Bacterial genome-wide association studies (GWAS) can identify novel resistance genes but must control for genetic confounders while maintaining power. Here, we show that compared to single-locus GWAS, conducting GWAS conditioned on known resistance mutations reduces the number of false positives and identifies a G70D mutation in the RplD 50S ribosomal protein L4 as significantly associated with increased azithromycin resistance (p-value = 1.08 × 10-11). We experimentally confirm our GWAS results and demonstrate that RplD G70D and other macrolide binding site mutations are prevalent (present in 5.42% of 4850 isolates) and widespread (identified in 21/65 countries across two decades). Overall, our findings demonstrate the utility of conditional associations for improving the performance of microbial GWAS and advance our understanding of the genetic basis of macrolide resistance.

Surveillance and molecular epidemiology of Neisseria gonorrhoeae isolates in Shenzhen, China, 2010-2017

OBJECTIVES

The development and emergence of antimicrobial resistance in Neisseria gonorrhoeae (NG) have become a major public-health problem worldwide. This study aimed to analyse the antimicrobial susceptibility and molecular characteristics of NG isolates in Shenzhen, China.

METHODS

A total of 1282 NG isolates were consecutively collected between 2010 and 2017. Patient demographic information was also collected. MICs of ceftriaxone, spectinomycin, ciprofloxacin, azithromycin and penicillin were determined by agar dilution. Isolates were genotyped using N. gonorrhoeae multi-antigen sequence typing (NG-MAST).

RESULTS

Among the isolates, 97.4% were resistant to ciprofloxacin and 68.2% to penicillin. Moreover, 5.0% showed decreased susceptibility to ceftriaxone (CRO^D) and 17.3% were resistant to azithromycin (AZM-R); 1.3% were simultaneously CRO^D and AZM-R. All isolates were susceptible to spectinomycin. Increasing ceftriaxone MICs were found from 2010 to 2017. A total of 427 sequence types (STs) and 68 genogroups were identified from 724 isolates. ST5061, ST3741 and ST1766 were observed across the study years. ST14638 (n = 3) was predominant among 32 CRO^D isolates. Prevalent STs were ST5061 (n = 6), ST1866 (n = 5) and ST11133 (n = 5) among 96 AZM-R isolates.

CONCLUSIONS

A high prevalence of isolates resistant to ciprofloxacin and penicillin was found in this study. Azithromycin, one antimicrobial of dual antimicrobial therapy recommended by the WHO, showed a high prevalence of resistance. The other, ceftriaxone, can be used continuously in this region owing to lower resistance levels. However, the emergence of CRO^D and decreasing susceptibility to ceftriaxone indicate that continuous antimicrobial resistance surveillance is essential.

Neisseria gonorrhoeae 23S rRNA A2059G mutation is the only determinant necessary for high-level azithromycin resistance and improves in vivo biological fitness

Objectives

The global emergence of Neisseria gonorrhoeae isolates displaying high-level azithromycin resistance is a major concern for the currently recommended azithromycin/ceftriaxone dual therapy. N. gonorrhoeae high-level azithromycin resistance has been associated with an A2059G mutation in 23S rRNA. Here we investigated the specific contribution of this 23S rRNA A2059G mutation to high-level azithromycin resistance and its impact on biological fitness.

Methods

A2059G/G2059A alleles were specifically cloned into all four genomic copies of 23S rDNA of an azithromycin-susceptible isolate and a high-level azithromycin-resistant isolate. WT and mutant strains were subsequently investigated for azithromycin susceptibility using the agar dilution method. In addition, their biological fitness was studied by comparative liquid growth in the presence of hydrophobic and amphipathic compounds, by competition assays in a mouse vaginal tract infection model and by competition assays for invasion and intracellular survival.

Results

Azithromycin susceptibility analyses showed that the 23S rRNA A2059G mutation is the only genetic determinant required for N. gonorrhoeae to display the high-level azithromycin resistance phenotype. Further analysis of biological fitness showed that strains containing 2059G outcompeted isogenic strains containing 2059A for colonization in the mouse vaginal tract infection model and for invasion of HeLa cervical epithelial cells. Furthermore, the A2059G mutation enhanced growth in the presence of lithocholic acid or Triton X-100.

Conclusions

Our findings that the 23S rRNA A2059G mutation is sufficient for high-level azithromycin resistance and that this mutation generally enhanced the biological fitness of N. gonorrhoeae have important implications for the currently recommended treatment policies and antimicrobial stewardship programmes.

Genomic Characterization of Neisseria gonorrhoeae Strains from 2016 U.S. Sentinel Surveillance Displaying Reduced Susceptibility to Azithromycin

In 2016, the proportion of Neisseria gonorrhoeae isolates with reduced susceptibility to azithromycin rose to 3.6%. A phylogenetic analysis of 334 N. gonorrhoeae isolates collected in 2016 revealed a single, geographically diverse lineage of isolates with MICs of 2 to 16 μg/ml that carried a mosaic-like mtr locus, whereas the majority of isolates with MICs of ≥16 μg/ml appeared sporadically and carried 23S rRNA mutations. Continued molecular surveillance of N. gonorrhoeae isolates will identify new resistance mechanisms.

Increasing prevalence of Neisseria gonorrhoeae with decreased susceptibility to ceftriaxone and resistance to azithromycin in Hangzhou, China (2015-17)

Objectives

Development of resistance in Neisseria gonorrhoeae to ceftriaxone monotherapy or ceftriaxone plus azithromycin dual therapy is a global public health concern. The aim of this study was to analyse the trend in antimicrobial resistance in Hangzhou, China, over the period 2015-17.

Methods

In total, 379 clinical isolates were collected from seven hospitals and antimicrobial susceptibility was determined using the agar dilution method. Isolates showing resistance to ceftriaxone, azithromycin or cefixime were analysed for the presence of resistance determinants. STs were determined with the N. gonorrhoeae multiantigen sequence typing (NG-MAST) method and phylogenetic analysis and strain clustering was determined using porB and tbpB sequences.

Results

Ceftriaxone resistance, decreased susceptibility to ceftriaxone and azithromycin resistance were observed in 3%, 17% and 21% of the isolates, respectively. This resulted in 5% of the isolates showing both decreased susceptibility to ceftriaxone and azithromycin resistance. Importantly, resistance levels to ceftriaxone and azithromycin increased over the study period, resulting in 5% ceftriaxone resistance, 27% decreased susceptibility to ceftriaxone and 35% azithromycin resistance in 2017 and 11% of the isolates showing both decreased susceptibility to ceftriaxone and azithromycin resistance. Phylogenetic and cluster analysis showed the emergence and expansion in 2017 of a clonally related cluster containing strains with high abundance of decreased susceptibility to ceftriaxone and/or cefixime, which was related to the presence of the mosaic penA allele X. Co-resistance to azithromycin was also observed in this cluster.

Conclusions

Our findings have major implications for the future reliability of ceftriaxone monotherapy and ceftriaxone plus azithromycin dual therapy in China.

Antimicrobial Resistance And Molecular Characteristics Among Neisseria gonorrhoeae Clinical Isolates In A Chinese Tertiary Hospital

Purpose

The resistance of N. gonorrhoeae to antimicrobial agents has been increasing year by year due to the overuse of antibiotics. The primary aims of the present study were to investigate the molecular characteristics of the clinical isolates of Neisseria gonorrhoeae and the resistance to azithromycin in a Chinese tertiary hospital.

Methods

From January 2014 to May 2017, a total of 55 clinical isolates of N. gonorrhoeae were collected. Genes associated with azithromycin resistance (AZM-R), including mutations in 23S rRNA alleles, the mtrR promoter and coding regions, and rplD and rplV were evaluated by PCR and DNA sequencing. All clinical isolates were subjected to N. gonorrhoeae multiantigen sequence typing (NG-MAST), while the AZM-R isolates were further characterized by multilocus sequence typing (MLST).

Results

The AZM-R rate in this study was 23.64% (13/55), and a single (A)-nucleotide deletion mutation in the mtrR promoter region, a G45D mutation in the mtrR coding region, a point mutation in rplD, and an A2047G mutation in 23S rRNA alleles were detected in 13, 4, 3 and 4 isolates, respectively; no mutations were found in rplV. There was no significant difference in the mtrR coding region mutation rate between the azithromycin-sensitive and AZM-R groups (P > 0.05); however, there was a significant difference in the mutation rate of the mtrR promoter region (P < 0.05). Among the 55 isolates studied, 43 distinct NG-MAST were determined, while the AZM-R isolates were allocated into 10 distinct MLST/NG-MAST combinations. All three isolates with high-level AZM-R belonged to the sequence types (STs) NG-MAST ST1866 and MLST ST10899.

Conclusion

N. gonorrhoeae clinical isolates from Wenzhou, eastern China, showed considerable genetic diversity. Measures should be implemented to monitor the spread of the NG-MAST ST1866 and MLST ST10899 N. gonorrhoeae clones, which exhibit high-level AZM-R in eastern China.

Emergence and Spread of Neisseria gonorrhoeae Strains with High-Level Resistance to Azithromycin in Taiwan from 2001 to 2018

A total of 598 Neisseria gonorrhoeae isolates obtained from patients in Taiwan from 2001 to 2018 were evaluated. The MICs of ceftriaxone (CRO) and azithromycin (AZM) against the isolates were determined by the agar dilution method. N. gonorrhoeae isolates with AZM MICs of ≥1 μg/ml were identified and characterized by the presence of AZM resistance determinants. For high-level AZM-resistant (AZM-HLR) isolates (MIC ≥ 256 μg/ml), genotyping was performed using multilocus sequence typing (MLST) and N. gonorrhoeae multiantigen sequence typing (NG-MAST). Among the N. gonorrhoeae isolates studied, 8.7% (52/598) exhibited AZM MICs of ≥1 μg/ml. Thirteen of the 52 isolates contained A2059G (23S rRNA NG-STAR type 1) or C2611T (23S rRNA NG-STAR type 2) mutations. The prevalence of the A2059G mutation was higher in AZM-HLR isolates (P < 0.001). The -35A deletion in the promoter region of the mtrR gene did not differ between AZM-HLR isolates (100%, 10/10) and the isolates with AZM MICs of 1 μg/ml to 64 μg/ml (95.2%, 40/42) (P = 1.000). The presence of mutations in the mtrR coding region was significantly different between these two groups at 90% (9/10) and 26.2% (11/42), respectively (P < 0.001). The AZM-HLR isolates, all carrying four mutated A2059G alleles, a -35A deletion, and G45D, were classified as MLST 12039/10899 and NG-MAST 1866/16497. In conclusion, Taiwan is among the countries reporting gonococci with high-level resistance to AZM so that a single dose of 1 g ceftriaxone intramuscularly as the first choice for management of N. gonorrhoeae infection should be evaluated.

Typing and antimicrobial susceptibility of 134 Neisseria gonorrhoeae strains from Southern Spain

OBJECTIVE

Last guidelines have recommended the introduction of dual antimicrobial therapy in order to avoid treatment failure. In the present report, the susceptibility to some antibiotics was evaluated, and the typing of Neisseria gonorrhoeae strains was performed.

METHODS

Gonococcal isolates were tested for susceptibility according to the recommendations of both CLSI and EUCAST. A total of 134 isolates were typed by the NG-MAST technique.

RESULTS

Seventy-two different N. gonorrhoeae types were found, and the most frequent types obtained were ST 1407, ST 14958, ST 7192, ST 13251 and ST 5405. If CLSI/EUCAST criteria were applied, a ST 9807 type was found nonsusceptible to ceftriaxone and cefixime (MIC 0.5 mg/L), and a ST 12800 type was found nonsusceptible only to cefixime (MIC 0.25 mg/L). When only EUCAST breakpoints were taken into account, three strains were also resistant to cefixime (MIC 0.25 mg/L) and three isolates were resistant to ceftriaxone (MIC 0.19, 0.16 and 0.25 mg/L, respectively). The majority of strains were resistant to ciprofloxacin (68.6%), and all N. gonorrhoeae strains were susceptible to spectinomycin; 9.7% of isolates were resistant to azithromycin.

CONCLUSIONS

Molecular typing may be a useful tool to predict antimicrobial resistance. High rates of resistance to penicillin, tetracycline and ciprofloxacin were found in this area. It is highly recommended to carry out antimicrobial susceptibility in all gonorrhoea cases and to identify treatment failures to verify emerging resistance.

Emergence of Neisseria gonorrhoeae Strains Harboring a Novel Combination of Azithromycin-Attenuating Mutations

The nimbleness of Neisseria gonorrhoeae to evade the effect of antibiotics has perpetuated the fight against antibiotic-resistant gonorrhea for more than 80 years. The ability to develop resistance to antibiotics is attributable to its indiscriminate nature in accepting and integrating exogenous DNA into its genome. Here, we provide data demonstrating a novel combination of the 23S rRNA A2059G mutation with a mosaic-multiple transferable resistance (mosaic-mtr) locus haplotype in 14 N. gonorrhoeae isolates with high-level azithromycin MICs (≥256 μg/ml), a combination that may confer more fitness than in previously identified isolates with high-level azithromycin resistance. To our knowledge, this is the first description of N. gonorrhoeae strains harboring this novel combination of resistance determinants. These strains were isolated at two independent jurisdictions participating in the Gonococcal Isolate Surveillance Project (GISP) and in the Strengthening the U.S. Response to Resistant Gonorrhea (SURRG) project. The data suggest that the genome of N. gonorrhoeae continues to shuffle its genetic material. These findings further illuminate the genomic plasticity of N. gonorrhoeae, which allows this pathogen to develop mutations to escape the inhibitory effects of antibiotics.

Evaluation of the accuracy of molecular assays targeting the mutation A2059G for detecting high-level azithromycin resistance in Neisseria gonorrhoeae: a systematic review and meta-analysis

BACKGROUND

Neisseria gonorrhoeae resistance to azithromycin has become a significant public health concern globally, and high-level azithromycin-resistant (HL-AzmR) isolates have emerged frequently. However, high-level azithromycin resistance is considered to be caused by mutated alleles of 23S rRNA gene at position 2059, and identification of HL-AzmR isolates mainly relies on agar dilution method or E-test method. This study aimed to assess the accuracy of the molecular assays targeting the mutation A2059G for identifying HL-AzmR isolates and thereby determine the association between the mutation and high-level azithromycin resistance.

METHODS

Two researchers independently searched six databases to identify studies published from the launch of each database to October 15, 2017. The fixed effects model was used to estimate the pooled sensitivity rate, specificity rate, positive predictive value (PPV), and negative predictive value (NPV). Summary receiver operating characteristic curves were generated, and the area under the curve (AUC) was determined to estimate the overall performance of the assays. The Deeks' test was conducted to evaluate potential publication bias.

RESULTS

Ten relevant studies were included in the meta-analysis to assess the synthetic accuracy of the molecular assays. The molecular assays had the synthetic sensitivity rate of 97.8% and the synthetic specificity rate of 99.1%. And the aggregated PPV and NPV were 96.4% and 99.5%, respectively. AUC was 0.99, suggesting a close relation existing between the mutation A2059G and high-level azithromycin resistance. This indicated that the molecular assays targeting the mutation A2059G have relatively high overall accuracy for identifying HL-AzmR N. gonor-rhoeae isolates. Publication bias was statistically significant.

CONCLUSION

The mutation A2059G is the critical factor causing high-level azithromycin resistance. Hence, molecular methods are recommended to be put into clinical practice by commercialization, which will assist clinicians to prescribe more precisely.

Transcriptome Analysis of Neisseria gonorrhoeae during Natural Infection Reveals Differential Expression of Antibiotic Resistance Determinants between Men and Women

Recent emergence of antimicrobial resistance of Neisseria gonorrhoeae worldwide has resulted in limited therapeutic choices for treatment of infections caused by this organism. We performed global transcriptomic analysis of N. gonorrhoeae in subjects with gonorrhea who attended a Nanjing, China, sexually transmitted infection (STI) clinic, where antimicrobial resistance of N. gonorrhoeae is high and increasing. We found that N. gonorrhoeae transcriptional responses to infection differed in genital specimens taken from men and women, particularly antibiotic resistance gene expression, which was increased in men. These sex-specific findings may provide a new approach to guide therapeutic interventions and preventive measures that are also sex specific while providing additional insight to address antimicrobial resistance of N. gonorrhoeae.

Neisseria gonorrhoeae is a bacterial pathogen responsible for the sexually transmitted infection gonorrhea. Emergence of antimicrobial resistance (AMR) of N. gonorrhoeae worldwide has resulted in limited therapeutic choices for this infection. Men who seek treatment often have symptomatic urethritis; in contrast, gonococcal cervicitis in women is usually minimally symptomatic, but may progress to pelvic inflammatory disease. Previously, we reported the first analysis of gonococcal transcriptome expression determined in secretions from women with cervical infection. Here, we defined gonococcal global transcriptional responses in urethral specimens from men with symptomatic urethritis and compared these with transcriptional responses in specimens obtained from women with cervical infections and in vitro-grown N. gonorrhoeae isolates. This is the first comprehensive comparison of gonococcal gene expression in infected men and women. RNA sequencing analysis revealed that 9.4% of gonococcal genes showed increased expression exclusively in men and included genes involved in host immune cell interactions, while 4.3% showed increased expression exclusively in women and included phage-associated genes. Infected men and women displayed comparable antibiotic-resistant genotypes and in vitro phenotypes, but a 4-fold higher expression of the Mtr efflux pump-related genes was observed in men. These results suggest that expression of AMR genes is programed genotypically and also driven by sex-specific environments. Collectively, our results indicate that distinct N. gonorrhoeae gene expression signatures are detected during genital infection in men and women. We propose that therapeutic strategies could target sex-specific differences in expression of antibiotic resistance genes.

IMPORTANCE Recent emergence of antimicrobial resistance of Neisseria gonorrhoeae worldwide has resulted in limited therapeutic choices for treatment of infections caused by this organism. We performed global transcriptomic analysis of N. gonorrhoeae in subjects with gonorrhea who attended a Nanjing, China, sexually transmitted infection (STI) clinic, where antimicrobial resistance of N. gonorrhoeae is high and increasing. We found that N. gonorrhoeae transcriptional responses to infection differed in genital specimens taken from men and women, particularly antibiotic resistance gene expression, which was increased in men. These sex-specific findings may provide a new approach to guide therapeutic interventions and preventive measures that are also sex specific while providing additional insight to address antimicrobial resistance of N. gonorrhoeae.