Genomic epidemiology and population structure of Neisseria gonorrhoeae from remote highly endemic Western Australian populations

There are three major Neisseria gonorrhoeae β-lactamase plasmid variants which are associated with specific lineages and carry distinct TEM alleles

Neisseria gonorrhoeae is a significant threat to global health with an estimated incidence of over 80 million cases each year and high levels of antimicrobial resistance. The gonococcal β-lactamase plasmid, pbla, carries the TEM β-lactamase, which requires only one or two amino acid changes to become an extended-spectrum β-lactamase (ESBL); this would render last resort treatments for gonorrhoea ineffective. Although pbla is not mobile, it can be transferred by the conjugative plasmid, pConj, found in N. gonorrhoeae. Seven variants of pbla have been described previously, but little is known about their frequency or distribution in the gonococcal population. We characterised sequences of pbla variants and devised a typing scheme, Ng_pblaST that allows their identification from whole genome short-read sequences. We implemented Ng_pblaST to assess the distribution of pbla variants in 15 532 gonococcal isolates. This demonstrated that only three pbla variants commonly circulate in gonococci, which together account for >99 % of sequences. The pbla variants carry different TEM alleles and are prevalent in distinct gonococcal lineages. Analysis of 2758 pbla-containing isolates revealed the co-occurrence of pbla with certain pConj types, indicating co-operativity between pbla and pConj variants in the spread of plasmid-mediated AMR in N. gonorrhoeae. Understanding the variation and distribution of pbla is essential for monitoring and predicting the spread of plasmid-mediated β-lactam resistance in N. gonorrhoeae.

Whole-Genome Sequencing of Pathogenic Bacteria-New Insights into Antibiotic Resistance Spreading

In recent years, the acquisition of antimicrobial resistance (AMR) by both pathogenic and opportunistic bacteria has become a major problem worldwide, which was already noticed as a global healthcare threat by the World Health Organization [...].

Recent advances in understanding and combatting Neisseria gonorrhoeae: a genomic perspective

The sexually transmitted infection (STI) gonorrhoea remains a major global public health concern. The World Health Organization (WHO) estimates that 87 million new cases in individuals who were 15 to 49 years of age occurred in 2016. The growing number of gonorrhoea cases is concerning given the rise in gonococci developing antimicrobial resistance (AMR). Therefore, a global action plan is needed to facilitate surveillance. Indeed, the WHO has made surveillance leading to the elimination of STIs (including gonorrhoea) a global health priority. The availability of whole genome sequence data offers new opportunities to combat gonorrhoea. This can be through (i) enhanced surveillance of the global prevalence of AMR, (ii) improved understanding of the population biology of the gonococcus, and (iii) opportunities to mine sequence data in the search for vaccine candidates. Here, we review the current status in Neisseria gonorrhoeae genomics. In particular, we explore how genomics continues to advance our understanding of this complex pathogen.

Bioinformatics tools used for whole-genome sequencing analysis of Neisseria gonorrhoeae: a literature review

Whole-genome sequencing (WGS) data are well established for the investigation of gonococcal transmission, antimicrobial resistance prediction, population structure determination and population dynamics. A variety of bioinformatics tools, repositories, services and platforms have been applied to manage and analyze Neisseria gonorrhoeae WGS datasets. This review provides an overview of the various bioinformatics approaches and resources used in 105 published studies (as of 30 April 2021). The challenges in the analysis of N. gonorrhoeae WGS datasets, as well as future bioinformatics requirements, are also discussed.

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

Objectives

To determine the association of Neisseria gonorrhoeae antimicrobial resistance and genotypes using N. gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR).

Methods

We characterized 124 N. gonorrhoeae isolates for their antimicrobial susceptibility profiles and NG-STAR ST characteristics using the guidelines of CLSI and EUCAST. The NG-STAR STs of seven loci were analysed. N. gonorrhoeae multiantigen sequence typing (NG-MAST) and MLST analysis was conducted in isolates with specific NG-STAR STs.

Results

NG-STAR differentiated 124 N. gonorrhoeae isolates into 84 STs, of which 66 STs were novel to the NG-STAR database. NG-STAR ST-199, ST-348, ST-428, ST-497 and ST-1138 were the predominant STs. Three N. gonorrhoeae isolates with ceftriaxone and cefixime MICs ≥1.0 mg/L were grouped as NG-STAR ST-233. NG-STAR ST-202 isolates (n=4) were associated with high azithromycin MICs and had an identical NG-MAST ST. The NG-STAR ST-348 group (n=5) comprised more isolates with reduced susceptibility to cefixime (n=4) than cefixime-susceptible isolates (n=1).

Conclusions

NG-STAR analysis differentiated N. gonorrhoeae isolates in settings with a high prevalence of antimicrobial resistance. Specific NG-STAR STs are associated with reduced susceptibility to ceftriaxone or cefixime and resistance to azithromycin in N. gonorrhoeae.

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.

Genomic and Phenotypic Variability in Neisseria gonorrhoeae Antimicrobial Susceptibility, England

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a global concern. Phylogenetic analyses resolve uncertainties regarding genetic relatedness of isolates with identical phenotypes and inform whether AMR is due to new mutations and clonal expansion or separate introductions by importation. We sequenced 1,277 isolates with associated epidemiologic and antimicrobial susceptibility data collected during 2013–2016 to investigate N. gonorrhoeae genomic variability in England. Comparing genetic markers and phenotypes for AMR, we identified 2 N. gonorrhoeae lineages with different antimicrobial susceptibility profiles and 3 clusters with elevated MICs for ceftriaxone, varying mutations in the penA allele, and different epidemiologic characteristics. Our results indicate N. gonorrhoeae with reduced antimicrobial susceptibility emerged independently and multiple times in different sexual networks in England, through new mutation or recombination events and by importation. Monitoring and control for AMR in N. gonorrhoeae should cover the entire population affected, rather than focusing on specific risk groups or locations.

Whole genome genetic variation and linkage disequilibrium in a diverse collection of Listeria monocytogenes isolates

We performed whole-genome multi-locus sequence typing for 2554 genes in a large and heterogenous panel of 180 Listeria monocytogenes strains having diverse geographical and temporal origins. The subtyping data was used for characterizing genetic variation and evaluating patterns of linkage disequilibrium in the pan-genome of L. monocytogenes. Our analysis revealed the presence of strong linkage disequilibrium in L. monocytogenes, with ~99% of genes showing significant non-random associations with a large majority of other genes in the genome. Twenty-seven loci having lower levels of association with other genes were considered to be potential “hot spots” for horizontal gene transfer (i.e., recombination via conjugation, transduction, and/or transformation). The patterns of linkage disequilibrium in L. monocytogenes suggest limited exchange of foreign genetic material in the genome and can be used as a tool for identifying new recombinant strains. This can help understand processes contributing to the diversification and evolution of this pathogenic bacteria, thereby facilitating development of effective control measures.

Septic arthritis due to Neisseria gonorrhoea in Western Australia

OBJECTIVE

To investigate the frequency, risk factors and long-term outcome of gonococcal arthritis in Western Australia (WA).

METHODS

A population-based data linkage study of patients with a hospital-based diagnosis of gonococcal arthritis (GA) in WA between 1990-2014. Demographics, standardised incidence rates (IR) per million and comorbidity accrued before (lookback 186 months ,IQR 86-267) and after the index hospital contact for GA (follow-up 100 months, IQR 60-209). are presented as frequency (%), median (interquartile range) or rates /1,000 months.

RESULTS

In total 98 patients were diagnosed with GA. The annual incidence of GA increased from 1.35 to 2.10 per million between 1990 and 2014, but the rate of GA complicating all gonococcal infections was stable around 0.25%. Female patients with GA (54%, n=53/98) were younger (24 vs 38 years), and more frequently identified as Indigenous (88% vs 49%) than male patients (46%, n=45/98) (p=0.002). Female patients had higher rates of prior infections (15.5 vs 8.1 per 1,000 months, p=0.002) and diabetes mellitus (15.9% vs 2.5%, p=0.03) and a longer hospital stay (10 vs 8 days, p=0.02). GA recurrence rate during follow-up was low (2%), but a broad range of comorbidities developed contributing to a 14% crude death rate.

CONCLUSIONS

GA stably complicates 0.25% of gonococcal infections in WA with young Indigenous females and middle-aged non-Indigenous males most affected. Prior infectious disease and diabetes mellitus are potential risk factors for GA in females. GA recurs rarely, but its development reflects a high risk of morbidity and mortality over the following ten years. This article is protected by copyright. All rights reserved.

Meningococcal Disease-Associated Prophage-Like Elements Are Present in Neisseria gonorrhoeae and Some Commensal Neisseria Species

Neisseria spp. possess four genogroups of filamentous prophages, termed Nf1 to 4. A filamentous bacteriophage from the Nf1 genogroup termed meningococcal disease-associated phage (MDA φ) is associated with clonal complexes of Neisseria meningitidis that cause invasive meningococcal disease. Recently, we recovered an isolate of Neisseria gonorrhoeae (ExNg63) from a rare case of gonococcal meningitis, and found that it possessed a region with 90% similarity to Nf1 prophages, specifically, the meningococcal MDA φ. This led to the hypothesis that the Nf1 prophage may be more widely distributed amongst the genus Neisseria. An analysis of 92 reference genomes revealed the presence of intact Nf1 prophages in the commensal species, Neisseria lactamica and Neisseria cinerea in addition to the pathogen N. gonorrhoeae. In N. gonorrhoeae, Nf1 prophages had a restricted distribution but were present in all representatives of MLST ST1918. Of the 160 phage integration sites identified, only one common insertion site was found between one isolate of N. gonorrhoeae and N. meningitidis. There was an absence of any obvious conservation of the receptor for prophage entry, PilE, suggesting that the phage may have been obtained by natural transformation. An examination of the restriction modification systems and mutated mismatch repair systems with prophage presence suggested that there was no obvious preference for these hosts. A timed phylogeny inferred that N. meningitidis was the donor of the Nf1 prophages in N. lactamica and N. gonorrhoeae. Further work is required to determine whether Nf1 prophages are active and can act as accessory colonization factors in these species.

Neisseria gonorrhoeae Population Genomics: Use of the Gonococcal Core Genome to Improve Surveillance of Antimicrobial Resistance

BACKGROUND

Gonorrhea, caused by the bacterium Neisseria gonorrhoeae, is a globally prevalent sexually transmitted infection. The dynamics of gonococcal population biology have been poorly defined due to a lack of resolution in strain typing methods.

METHODS

In this study, we assess how the core genome can be used to improve our understanding of gonococcal population structure compared with current typing schemes.

RESULTS

A total of 1668 loci were identified as core to the gonococcal genome. These were organized into a core genome multilocus sequence typing scheme (N gonorrhoeae cgMLST v1.0). A clustering algorithm using a threshold of 400 allelic differences between isolates resolved gonococci into discrete and stable core genome groups, some of which persisted for multiple decades. These groups were associated with antimicrobial genotypes and non-overlapping NG-STAR and NG-MAST sequence types. The MLST-STs were more widely distributed among core genome groups.

CONCLUSIONS

Clustering with cgMLST identified globally distributed, persistent, gonococcal lineages improving understanding of the population biology of gonococci and revealing its population structure. These findings have implications for the emergence of antimicrobial resistance in gonococci and how this is associated with lineages, some of which are more predisposed to developing antimicrobial resistance than others.

Characterization of antimicrobial resistance genes from Neisseria gonorrhoeae positive remnant Aptima urine specimens

Aim: To ascertain the antimicrobial resistance and strain types (STs) of Neisseria gonorrhoeae from 50 remnant Aptima urine specimens using molecular methods. Methods: Mutations predictive of resistance to six antibiotics were identified in eight genes. STs were determined using NG-MAST and NG-STAR. Results: All eight antimicrobial resistance genes could be characterized in 36 specimens. A total of 17 specimens were predicted to be susceptible to all antibiotics, including ceftriaxone. Decreased susceptibility to cefixime and ciprofloxacin resistance was predicted in 11 specimens (PBP2 type 34.001). Overall, 38/50 specimens were predicted to be ciprofloxacin susceptible; three were azithromycin resistant. Nineteen NG-MAST and 21 NG-STAR STs were noted. Conclusion: Molecular analysis of remnant Aptima specimens enabled the prediction of emerging gonococcal cefixime and azithromycin resistance which would otherwise have been undetected.

Neisseria gonorrhoeae ciprofloxacin-resistant strains were associated with Chlamydia trachomatis coinfection

Aim: This study aims to characterize circulating strains to predict their relationship with sexually transmitted microorganisms, Chlamydia trachomatis, HIV, HCV, Treponema pallidum, HPV, Mycoplasmas, in an Italian multiethnic area, which has revealed a recent increase of Neisseria gonorrhoeae first-line antibiotic resistance. Materials & methods: We performed N. gonorrhoeae multiantigen sequence typing and the N. gonorrhoeae sequence typing for antimicrobial resistance. Results: We identified mutations in genes conferring resistance to cephalosporins, macrolides, fluoroquinolones through por and tbpB loci, and we reported new combinations of already known alleles. N. gonorrhoeae resistance to ciprofloxacin was associated with C. trachomatis coinfection. Conclusion: This study's data proved the utility of a routine N. gonorrhoeae molecular characterization to monitor the evolution of antibiotic resistance and to detect the most effective clinical treatment.

Gen2Epi: an automated whole-genome sequencing pipeline for linking full genomes to antimicrobial susceptibility and molecular epidemiological data in Neisseria gonorrhoeae

BACKGROUND

Recent adva1nces in whole genome sequencing (WGS) based technologies have facilitated multi-step applications for predicting antimicrobial resistance (AMR) and investigating the molecular epidemiology of Neisseria gonorrhoeae. However, generating full scaffolds of N. gonorrhoeae genomes from short reads, and the assignment of molecular epidemiological information (NG-MLST, NG-MAST, and NG-STAR) to multiple assembled samples, is challenging due to required manual tasks such as annotating antimicrobial resistance determinants with standard nomenclature for a large number of genomes.

RESULTS

We present Gen2Epi, a pipeline that assembles short reads into full scaffolds and automatically assigns molecular epidemiological and AMR information to the assembled genomes. Gen2Epi is a command-line tool integrating third-party software and tailored specifically for N. gonorrhoeae. For its evaluation, the Gen2Epi pipeline successfully assembled the WGS short reads from 1484 N. gonorrhoeae samples into full-length genomes for both chromosomes and plasmids and was able to assign in silico molecular determinant information to each dataset automatically. The assemblies were generated using raw as well as trimmed short reads. The median genome coverage of full-length scaffolds and "N" statistics (N50, NG50, and NGA50) were higher than, or comparable to, previously published results and the scaffolding process improved the quality of the draft genome assemblies. Molecular antimicrobial resistant (AMR) determinants identified by Gen2Epi reproduced information for the 1484 samples as previously reported, including NG-MLST, NG-MAST, and NG-STAR molecular sequence types.

CONCLUSIONS

Gen2Epi can be used to assemble short reads into full-length genomes and assign accurate molecular marker and AMR information automatically from NG-STAR, NG-MAST, and NG-MLST. Gen2Epi is publicly available under "CC BY-NC 2.0 CA" Creative Commons licensing as a VirtualBox image containing the constituent software components running on the LINUX operating system (CentOS 7). The image and associated documentation are available via anonymous FTP at ftp://www.cs.usask.ca/pub/combi or ftp://ftp.cs.usask.ca/pub/combi.

A Whole-genome Sequencing Analysis of Neisseria gonorrhoeae Isolates in China: An Observational Study

BACKGROUND

Tracking the spread of the Neisseria gonorrhoeae strains with decreased susceptibility or resistance to cephalosporins is a major priority for global surveillance programmes. Whole-genome sequencing (WGS) has been widely used by increasing countries in North America, Europe, and Pacific to determine the decreased susceptible or resistance determinants of Neisseria gonorrhoeae, track the spread of these determinants throughout the gonococcal population at national or regional level. However, no studies to date have examined the genomic epidemiology of gonorrhea in Asia where the antimicrobial resistant strains of Neisseria gonorrhoeae appears to have emerged before disseminating the strains globally.

METHODS

We obtained clinical isolates and data from the China Gonococcal Resistance Surveillance Programme (China-GRSP) from 2012 to 2013. We sequenced the genomes of 435 clinical isolates of Neisseria gonorrhoeae, including 112 (25.6%) isolates with decreased susceptibility to ceftriaxone (Cfx-DS). We assessed the association between antimicrobial resistance genotype and phenotype. We also compared our data with the whole genome data of the isolates from the USA and the UK in the GenBank.

FINDINGS

The most prevalent MLST STs in our gonococcal population were MLST ST7827 (n = 74), followed by ST7365 (n = 58), ST1600 (n = 38), ST7367 (n = 35), and ST7363 (n = 29). MLST ST1901 which was reported as the predominant ST in the US was not found in our population. A total of 2512 strains, including additional 2077 published NG strains, were further included for phylogenetic analysis. It generated two distinct lineages - lineage 1 and lineage 2. Analysis of MLST ST1901 in the database indicate that most of MLST ST1901 isolates in the lineage2.6 were Cfx-DS isolates while all isolates in the lineage 2.1 were sensitive to ceftriaxone (77/110 vs. 0/13; p < 0.001). ST1901/lineage 2.6 is a ceftriaxone resistant clone which cannot distinguished by MLST genotyping. In the isolates from our study, the MICs of ceftriaxone for ST7363/lineage 2.6 isolates ranged from 0.008-0.125 mg/L (mean ± SD; 0.054 ± 0.043 mg/L) while those for ST7363/lineage 2.8 isolates ranged from 0.032-0.250 mg/L (0.134 ± 0.085 mg/L). All ST7363/lineage 2.8 isolates contained penA mosaic alleles.

INTERPRETATION

To our knowledge, current study is the first WGS-based analysis of gonococcal population at national level in Asia. China harbors the different predominant clones associated with decreased susceptibility to ceftriaxone from those clones circulated in other regions. The findings from the study can be not only used as baseline data for future studies in China but also contributable to our understanding on spread of N. gonorrhoeae and its resistant strains at regional and global levels.

FUNDING

The Chinese Academy Medical Sciences (CAMS) Initiative for Innovative Medicine.

Applications of genomics to slow the spread of multidrug-resistant Neisseria gonorrhoeae

Infections with Neisseria gonorrhoeae, a sexually transmitted pathogen that causes urethritis, cervicitis, and more severe complications, are increasing. Gonorrhea is typically treated with antibiotics; however, N. gonorrhoeae has rapidly acquired resistance to many antibiotic classes, and lineages with reduced susceptibility to the currently recommended therapies are emerging worldwide. In this review, we discuss the contributions of whole genome sequencing (WGS) to our understanding of resistant N. gonorrhoeae. Genomics has illuminated the evolutionary origins and population structure of N. gonorrhoeae and the magnitude of horizontal gene transfer within and between Neisseria species. WGS can be used to predict the susceptibility of N. gonorrhoeae based on known resistance determinants, track the spread of these determinants throughout the N. gonorrhoeae population, and identify novel loci contributing to resistance. WGS has also allowed more detailed epidemiological analysis of transmission of N. gonorrhoeae between individuals and populations than previously used typing methods. Ongoing N. gonorrhoeae genomics will complement other laboratory techniques to understand the biology and evolution of the pathogen, improve diagnostics and treatment in the clinic, and inform public health policies to limit the impact of antibiotic resistance.