Antimicrobial Resistance Profiling and Genome Analysis of the penA-60.001 Neisseria gonorrhoeae Clinical Isolates in China in 2021

Emerging epidemic of the Africa-type plasmid in penicillinase-producing Neisseria gonorrhoeae in Guangdong, China, 2013-2022

The prevalence of penicillinase-producing Neisseria gonorrhoeae (PPNG) is a crucial public health concern because of its resistance to penicillin and cephalosporins. From 2013 to 2022, a total of 1748 N. gonorrhoeae isolates from Guangdong, China, were examined for their antibiotic susceptibility and molecular epidemiological characteristics. PPNG prevalence increased markedly from 37.25% to 63.87%. This increase was accompanied by a shift in predominant plasmid types carried by PPNG isolates: the rate of PPNG isolates carrying the Africa-type plasmid increased from 18.42% to 91.55%, whereas the rate of isolates carrying the Asia-type plasmid decreased from 81.58% to 7.58%. The prevalence of blaTEM-135, which is linked to cephalosporin resistance, declined from 52.63% to 4.37%, whereas that of blaTEM-1 increased from 47.37% to 86.88%, and new blaTEM variants emerged (10.99% by 2022). Most blaTEM-1 (88.26%) and new blaTEM alleles (83.70%) were associated with the Africa-type plasmid, whereas 86.79% of blaTEM-135 alleles were linked to the Asia-type plasmid. Resistance to ceftriaxone was higher in the Asia-type group (11.67%) than in the Africa-type, Toronto/Rio-type and non-PPNG groups. Genotyping identified diverse sequence types (STs) among PPNGs, in which MLST ST7363, NG-STAR ST2477, NG-MAST ST17748, and NG STAR CC1124 were predominant. This study underscores the rising prevalence of PPNG in Guangdong driven by clonal expansion and changing plasmid dynamics, affecting cephalosporin resistance and highlighting the need for continued surveillance and research into effective treatment strategies.

An overview of potential combination therapies with ceftriaxone as a treatment for gonorrhoea

INTRODUCTION

Ceftriaxone is the last available single dose therapy for gonorrhea that effectively treats infections at all sites. Over a quarter of isolates are now resistant to ceftriaxone in some countries. The introduction of carefully chosen combination therapy with ceftriaxone could retard the emergence of ceftriaxone resistance.

AREAS COVERED

This review summarizes the findings of a PubMed search on the use of partner antimicrobial that could be used with ceftriaxone to prevent the emergence and spread of ceftriaxone resistance. We review 16 antimicrobials that could be partnered with ceftriaxone in terms of pharmacokinetic and pharmacodynamic compatibilities, activity against ceftriaxone resistant isolates and probability of antimicrobial resistance emerging.

EXPERT OPINION

Of these 16 antimicrobials, we reject antimicrobials such as fosfomycin due to poor clinical efficacy and tigecycline due to its considerably longer half-life which would likely select for tetracycline resistance. The most promising agents for combination with ceftriaxone are zoliflodacin, delafloxacin, sitafloxacin, eravacycline and possibly gepotidacin and gentamicin. Clinical studies should be conducted to evaluate the efficacy of these combinations on the eradication of N. gonorrhoeae and their impact on AMR in N. gonorrhoeae and other bacterial species.

Molecular epidemiology of Neisseria gonorrhoeae isolates in Russia, 2015-2023: current trends and forecasting

Introduction

The emergence of multidrug resistance in N. gonorrhoeae is a serious global problem, and gonorrhea may soon become an incurable disease. The aim of the study was to characterize the N. gonorrhoeae population in Russia from 2015 to 2023 and predict the potential spread of the most concerning clones.

Methods

A total of 996 N. gonorrhoeae isolates were examined during the analyzed period. Ceftriaxone and azithromycin susceptibility testing were performed using the agar dilution method. Microarray-based assays and sequencing were employed to identify the genotypes and genetic markers of antimicrobial resistance.

Results

No ceftriaxone-resistant isolates were found in Russia, however, the number of isolates with reduced susceptibility to ceftriaxone has increased to 22.6% in recent years. Since 2020, approximately 12.5% of isolates have exhibited resistance to azithromycin annually. Two clusters of isolates pose a particular threat to Russia: NG-MAST G2212, linked to MLST 1901/1902, carries a mosaic structure in the penA gene; G12302, linked to MLST 9363, contains mosaic alleles in the mtrR and mtrD genes. Additionally, two new high-risk genogroups were characterized: G18898 and G16206. Both are associated with MLST 10314 and harbor mosaic variants of penA or mtrR/mtrD. Analysis of time series data suggests that isolates with mosaic alleles are unlikely to be eradicated from the population in the near future, potentially worsening the epidemiological situation of gonorrhea in Russia.

Conclusions

The native genetic strains of N. gonorrhoeae in Russia, which are susceptible to cephalosporins and macrolides, are being progressively replaced by globally dominant lineages. To further characterize this epidemiologic shift, ongoing surveillance strategies using molecular epidemiology and the identification of genetic markers will be crucial in curbing the growth and spread of N. gonorrhoeae resistance. Such efforts are vital in ensuring the availability of effective treatments for gonococcal infection.

Molecular screening to track ceftriaxone-resistant FC428-like Neisseria gonorrhoeae strains' dissemination in four provinces of China, 2019 to 2021

BackgroundThe global dissemination of ceftriaxone-resistant Neisseria gonorrhoeae FC428-like strains poses a public health concern. To assess and follow their spread, establishing effective antimicrobial resistance (AMR) surveillance systems is essential.AimThis study aimed to track ceftriaxone-resistant FC428-like strains in parts of China, using a molecular screening tool.MethodsSamples were collected from Sichuan, Zhejiang, Shanghai, and Guangdong provinces between 2019 and 2021. We employed a rapid molecular tool - the high-resolution melting analysis-based FC428 (HRM-FC428) assay, to screen for FC428-like strains. All FC428-like strains detected were further characterised by genotyping and PCR-sequencing.ResultsOf 1,042 tested samples, 44 harboured the penA-60.001 allele linked to ceftriaxone resistance, revealing a 4.2% prevalence of FC428-like strains. The HRM-FC428 assay additionally uncovered six strains with mosaic penA-195.001 or penA-232.001 alleles, both bearing the A311V mutation, a ceftriaxone resistance marker. During the study, the prevalence of FC428-like strains among overall samples appeared to increase, with rates of 2.8% (11/395) in 2019, 4.2% (16/378) in 2020, and 6.3% (17/269) in 2021. Some strains' sequence types (ST)s were identified across provinces (e.g. ST1903, ST1600) and most strains (24/44) were ST1903, an ST also reported in other regions/countries, suggesting local evolution and global transmission.ConclusionOur work underscores the value of culture-independent antimicrobial resistance monitoring and validates the use of molecular diagnostic tools, like the HRM-FC428 assay for this purpose. This study offers insights into the complex landscape of ceftriaxone-resistant N. gonorrhoeae, emphasising the importance of continued surveillance and global collaboration to mitigate this growing public health threat.

Assessing novel partner antimicrobials to protect ceftriaxone against gonococcal resistance: An in vitro evaluation

BACKGROUND

The emergence of ceftriaxone-resistant Neisseria gonorrhoeae poses a significant threat to existing treatment regimens. Our study aimed to assess the efficacy of antimicrobials that could be combined with ceftriaxone to reduce the probability of ceftriaxone resistance emerging and spreading in N. gonorrhoeae.

METHODS AND RESULTS

Broth microdilution was used to determine the minimal inhibitory concentrations (MICs) for a panel of ceftriaxone-resistant (WHO X, Y, Z) and ceftriaxone-susceptible (WHO L, N, P) N. gonorrhoeae WHO reference strains for the following antimicrobials: ceftriaxone, doxycycline, azithromycin, zoliflodacin, fosfomycin, pristinamycin, ramoplanin, gentamicin and NAI-107. The MICs for zoliflodacin and pristinamycin for all strains were lower than or equal to the available breakpoints. A checkerboard assay was used to determine the drug-drug combination effect, which showed either an indifferent or an additive effect for all the combinations tested with ceftriaxone.

CONCLUSIONS

The low MICs of zoliflodacin and pristinamycin for the three ceftriaxone-resistant strains suggest that these antimicrobials could be used as partner drugs with ceftriaxone to reduce the probability of ceftriaxone resistance spreading in areas with a high prevalence of ceftriaxone resistance.

Cyr SB, Schlanger K, Raphael BH, Kersh EN, Joseph SJ. Emergence and evolution of mosaic penA-60 and penA-237 alleles in a Neisseria gonorrhoeae core genogroup that was historically susceptible to extended spectrum cephalosporins

Introduction

Neisseria gonorrhoeae (Ng) has successively developed resistance to all previously recommended antimicrobial therapies, with ceftriaxone being the last option for monotherapy of gonorrhea. Global emergence and international spread of the FC428 clone derived mosaic penA-60 allele, associated with highlevel ceftriaxone minimum inhibitory concentrations (MICs) in non FC428 clone Ng lineages, has become an increasing concern. The penA-60 allele carrying Ng was first identified in the U.S. in Las Vegas, Nevada (2019; GCWGS-102723), with a multi-locus sequence type (MLST)-1901 strain, in a non FC428 clone Ng lineage, which is associated with a historically ceftriaxone susceptible core genogroup. Later in 2022, an allele genetically similar to penA-60, mosaic penA-237, was identified in the UK (H22-722) and France (F92) with high-level ceftriaxone MICs and both belonged to MLST-1901.

Methods

In this study, we assessed phylogenomic relatedness and antimicrobial resistance (AMR) determinant profiles of these three isolates with high-level ceftriaxone MICs among a global collection of 2,104 genomes belonging to the MLST-1901 core genome cluster group 31, which includes strains separated by a locus threshold of 200 or fewer differences (Ng_cgc_200). Recombination events in and around the penA coding region were catalogued and potential sources of inter species recombinant DNA were also inferred.

Results

The global population structure of MLST-1901 core genogroup falls into 4 major lineages. Isolates GCWGS-10723, F92, and H22-722 clustered within Lineage 1, which was dominated by non-mosaic penA-5 alleles. These three isolates formed a clade within Lineage 1 that consisted of isolates from North America and southeast Asia. Neisseria subflava and Neisseria sicca were identified as likely progenitors of two independent recombination events that may have led to the generation of mosaic penA-60 and penA-237, within a possible non-mosaic penA-5 background.

Discussions

Our study suggests that there are multiple evolutionary pathways that could generate concerning mosaic penA alleles via homologous recombination of historically susceptible Ng lineages with Neisseria commensals. Enhanced surveillance of gonococcal strains and Neisseria commensals is crucial for understanding of the evolution of AMR, particularly in less-studied regions (e.g., Asia), where high-level ceftriaxone MICs and multi-drug resistance are more prevalent.

Managing treatment failure in Neisseria gonorrhoeae infection: current guidelines and future directions

Due to the continued emergence of resistance to extended-spectrum cephalosporin antibiotics, clinicians are increasingly more likely to encounter cases of Neisseria gonorrhoeae treatment failure. The current international treatment guidelines offer few regimens for cases of N gonorrhoeae infection that do not respond to first-line therapy, and there are many complexities that should be considered with such regimens; these include regional variations in resistance to alternative agents, access to different antibiotics, and penetration of those antibiotics within different tissues. Further, such regimens do not account for the challenges of treating pharyngeal infections; many patients who have not responded to treatment with extended-spectrum cephalosporin antibiotics to date have had pharyngeal involvement. In addition, pharyngeal infections play a pivotal role in the emergence and spread of antimicrobial resistance in N gonorrhoeae and are more difficult to treat than urogenital infections because of the unfavourable pharmacokinetics of cephalosporins in pharyngeal tissues. Here, we summarise the current guidelines, provide additional approaches and considerations for clinicians, and highlight knowledge gaps that should be addressed to ensure appropriate therapy in cases of treatment failure.

World Health Organization Enhanced Gonococcal Antimicrobial Surveillance Programme, Cambodia, 2023

To determine antimicrobial susceptibility of Neisseria gonorrhoeae, we analyzed phenotypes and genomes of 72 isolates collected in Cambodia in 2023. Of those, 9/72 (12.5%) were extensively drug resistant, a 3-fold increase from 2022. Genomic analysis confirmed expansion of newly emerging resistant clones and ongoing resistance emergence across new phylogenetic backbones.