Genetic characterisation of Neisseria gonorrhoeae resistant to both ceftriaxone and azithromycin

The novel 2024 WHO Neisseria gonorrhoeae reference strains for global quality assurance of laboratory investigations and superseded WHO N. gonorrhoeae reference strains-phenotypic, genetic and reference genome characterization

OBJECTIVES

MDR and XDR Neisseria gonorrhoeae strains remain major public health concerns internationally, and quality-assured global gonococcal antimicrobial resistance (AMR) surveillance is imperative. The WHO global Gonococcal Antimicrobial Surveillance Programme (GASP) and WHO Enhanced GASP (EGASP), including metadata and WGS, are expanding internationally. We present the phenotypic, genetic and reference genome characteristics of the 2024 WHO gonococcal reference strains (n = 15) for quality assurance worldwide. All superseded WHO gonococcal reference strains (n = 14) were identically characterized.

MATERIAL AND METHODS

The 2024 WHO reference strains include 11 of the 2016 WHO reference strains, which were further characterized, and four novel strains. The superseded WHO reference strains include 11 WHO reference strains previously unpublished. All strains were characterized phenotypically and genomically (single-molecule PacBio or Oxford Nanopore and Illumina sequencing).

RESULTS

The 2024 WHO reference strains represent all available susceptible and resistant phenotypes and genotypes for antimicrobials currently and previously used (n = 22), or considered for future use (n = 3) in gonorrhoea treatment. The novel WHO strains include internationally spreading ceftriaxone resistance, ceftriaxone resistance due to new penA mutations, ceftriaxone plus high-level azithromycin resistance and azithromycin resistance due to mosaic MtrRCDE efflux pump. AMR, serogroup, prolyliminopeptidase, genetic AMR determinants, plasmid types, molecular epidemiological types and reference genome characteristics are presented for all strains.

CONCLUSIONS

The 2024 WHO gonococcal reference strains are recommended for internal and external quality assurance in laboratory examinations, especially in the WHO GASP, EGASP and other GASPs, but also in phenotypic and molecular diagnostics, AMR prediction, pharmacodynamics, epidemiology, research and as complete reference genomes in WGS analysis.

Management of Neisseria gonorrhoeae infection: from drug resistance to drug repurposing

INTRODUCTION

Neisseria gonorrhoeae is a common sexually transmitted disease connected with extensive drug resistance to many antibiotics. Presently, only expanded spectrum cephalosporins (ceftriaxone and cefixime) and azithromycin remain useful for its management.

AREAS COVERED

New chemotypes for the classical antibiotic drug target gyrase/topoisomerase IV afforded inhibitors with potent binding to these enzymes, with an inhibition mechanism distinct from that of fluoroquinolones, and thus less prone to mutations. The α-carbonic anhydrase from the genome of this bacterium (NgCAα) was also validated as an antibacterial target.

EXPERT OPINION

By exploiting different subunits from the gyrase/topoisomerase IV as well as new chemotypes, two new antibiotics reached Phase II/III clinical trials, zoliflodacin and gepotidacin. They possess a novel inhibition mechanism, binding in distinct parts of the enzyme compared to the fluoroquinolones. Other chemotypes with inhibitory activity in these enzymes were also reported. NgCAα inhibitors belonging to a variety of classes were obtained, with several sulfonamides showing MIC values in the range of 0.25-4 µg/mL and significant activity in animal models of this infection. Acetazolamide and similar CA inhibitors might thus be repurposed as antiinfectives. The scientific/patent literature has been searched for on PubMed, ScienceDirect, Espacenet, and PatentGuru, from 2016 to 2024.

Policy, practice, and prediction: model-based approaches to evaluating N. gonorrhoeae antibiotic susceptibility test uptake in Australia

BACKGROUND

Antimicrobial resistance (AMR) represents a significant threat to global health with Neisseria gonorrhoea emerging as a key pathogen of concern. In Australia, the Australian Gonococcal Surveillance Program (AGSP) plays a critical role in monitoring resistance patterns. However, antibiotic susceptibility test (AST) uptake - a crucial component for effective resistance surveillance - remains to be a limiting factor. The study aims to model the processes involved in generating AST tests for N. gonorrhoea isolates within the Australian healthcare system and assess the potential impact of systematic and policy-level changes.

METHODS

Two models were developed. The first model was a mathematical stochastic health systems model (SHSM) and a Bayesian Belief Network (BBN) to simulate the clinician-patient dynamics influencing AST initiation. Key variables were identified through systematic literature review to inform the construction of both models. Scenario analyses were conducted with the modification of model parameters.

RESULTS

The SHSM and BBN highlighted clinician education and the use of clinical support tools as effective strategies to improve AST. Scenario analysis further identified adherence to guidelines and changes in patient-level factors, such as persistence of symptoms and high-risk behaviours, as significant determinants. Both models supported the notion of mandated testing to achieve higher AST initiation rates but with considerations necessary regarding practicality, laboratory constraints, and culture failure rate.

CONCLUSION

The study fundamentally demonstrates a novel approach to conceptualising the patient-clinician dynamic within AMR testing utilising a model-based approach. It suggests targeted interventions to educational, support tools, and legislative framework as feasible strategies to improve AST initiation rates. However, the research fundamentally highlights substantial research gaps in the underlying understanding of AMR.

Recent dynamics in Neisseria gonorrhoeae genomic epidemiology in Brazil: antimicrobial resistance and genomic lineages in 2017-20 compared to 2015-16

OBJECTIVES

Regular quality-assured WGS with antimicrobial resistance (AMR) and epidemiological data of patients is imperative to elucidate the shifting gonorrhoea epidemiology, nationally and internationally. We describe the dynamics of the gonococcal population in 11 cities in Brazil between 2017 and 2020 and elucidate emerging and disappearing gonococcal lineages associated with AMR, compare to Brazilian WGS and AMR data from 2015 to 2016, and explain recent changes in gonococcal AMR and gonorrhoea epidemiology.

METHODS

WGS was performed using Illumina NextSeq 550 and genomes of 623 gonococcal isolates were used for downstream analysis. Molecular typing and AMR determinants were obtained and links between genomic lineages and AMR (determined by agar dilution/Etest) examined.

RESULTS

Azithromycin resistance (15.6%, 97/623) had substantially increased and was mainly explained by clonal expansions of strains with 23S rRNA C2611T (mostly NG-STAR CC124) and mtr mosaics (mostly NG-STAR CC63, MLST ST9363). Resistance to ceftriaxone and cefixime remained at the same levels as in 2015-16, i.e. at 0% and 0.2% (1/623), respectively. Regarding novel gonorrhoea treatments, no known zoliflodacin-resistance gyrB mutations or gepotidacin-resistance gyrA mutations were found. Genomic lineages and sublineages showed a phylogenomic shift from sublineage A5 to sublineages A1-A4, while isolates within lineage B remained diverse in Brazil.

CONCLUSIONS

Azithromycin resistance, mainly caused by 23S rRNA C2611T and mtrD mosaics/semi-mosaics, had substantially increased in Brazil. This mostly low-level azithromycin resistance may threaten the recommended ceftriaxone-azithromycin therapy, but the lack of ceftriaxone resistance is encouraging. Enhanced gonococcal AMR surveillance, including WGS, is imperative in Brazil and other Latin American and Caribbean countries.

Multicentre double-blind randomised placebo-controlled trial evaluating the efficacy of the meningococcal B vaccine, 4CMenB (Bexsero), against Neisseria gonorrhoeae infection in men who have sex with men: the GoGoVax study protocol

INTRODUCTION

Gonorrhoea, the sexually transmissible infection caused by Neisseria gonorrhoeae, has a substantial impact on sexual and reproductive health globally with an estimated 82 million new infections each year worldwide. N. gonorrhoeae antimicrobial resistance continues to escalate, and disease control is largely reliant on effective therapy as there is no proven effective gonococcal vaccine available. However, there is increasing evidence from observational cohort studies that the serogroup B meningococcal vaccine four-component meningitis B vaccine (4CMenB) (Bexsero), licensed to prevent invasive disease caused by Neisseria meningitidis, may provide cross-protection against the closely related bacterium N. gonorrhoeae. This study will evaluate the efficacy of 4CMenB against N. gonorrhoeae infection in men (cis and trans), transwomen and non-binary people who have sex with men (hereafter referred to as GBM+).

METHODS AND ANALYSIS

This is a double-blind, randomised placebo-controlled trial in GBM+, either HIV-negative on pre-exposure prophylaxis against HIV or living with HIV (CD4 count >350 cells/mm3), who have had a diagnosis of gonorrhoea or infectious syphilis in the last 18 months (a key characteristic associated with a high risk of N. gonorrhoeae infection). Participants are randomised 1:1 to receive two doses of 4CMenB or placebo 3 months apart. Participants have 3-monthly visits over 24 months, which include testing for N. gonorrhoeae and other sexually transmissible infections, collection of demographics, sexual behaviour risks and antibiotic use, and collection of research samples for analysis of N. gonorrhoeae-specific systemic and mucosal immune responses. The primary outcome is the incidence of the first episode of N. gonorrhoeae infection, as determined by nucleic acid amplification tests, post month 4. Additional outcomes consider the incidence of symptomatic or asymptomatic N. gonorrhoeae infection at different anatomical sites (ie, urogenital, anorectum or oropharynx), incidence by N. gonorrhoeae genotype and antimicrobial resistance phenotype, and level and functional activity of N. gonorrhoeae-specific antibodies.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the St Vincent's Hospital Human Research Ethics Committee, St Vincent's Hospital Sydney, NSW, Australia (ref: 2020/ETH01084). Results will be disseminated in peer-reviewed journals and via presentation at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT04415424.

Ureidopenicillins Are Potent Inhibitors of Penicillin-Binding Protein 2 from Multidrug-Resistant Neisseria gonorrhoeae H041

Effective treatment of gonorrhea is threatened by the increasing prevalence of Neisseria gonorrhoeae strains resistant to the extended-spectrum cephalosporins (ESCs). Recently, we demonstrated the promise of the third-generation cephalosporin cefoperazone as an antigonococcal agent due to its rapid second-order rate of acylation against penicillin-binding protein 2 (PBP2) from the ESC-resistant strain H041 and robust antimicrobial activity against H041. Noting the presence of a ureido moiety in cefoperazone, we evaluated a subset of structurally similar ureido β-lactams, including piperacillin, azlocillin, and mezlocillin, for activity against PBP2 from H041 using biochemical and structural analyses. We found that the ureidopenicillin piperacillin has a second-order rate of acylation against PBP2 that is 12-fold higher than cefoperazone and 85-fold higher than ceftriaxone and a lower MIC against H041 than ceftriaxone. Surprisingly, the affinity of ureidopenicillins for PBP2 is minimal, indicating that their inhibitory potency is due to a higher rate of the acylation step of the reaction compared to cephalosporins. Enhanced acylation results from the combination of a penam scaffold with a 2,3-dioxopiperazine-containing R1 group. Crystal structures show that the ureido β-lactams overcome the effects of resistance mutations present in PBP2 from H041 by eliciting conformational changes that are hindered when PBP2 interacts with the weaker inhibitor ceftriaxone. Overall, our results support the potential of piperacillin as a treatment for gonorrhea and provide a framework for the future design of β-lactams with improved activity against ESC-resistant N. gonorrhoeae.

Current alternative therapies for treating drug-resistant Neisseria gonorrhoeae causing ophthalmia neonatorum

Ophthalmia neonatorum is a microbial contraction, damaging eyesight, occurring largely among neonates. Infants are particularly vulnerable to bacterial infections acquired during birth from infected mothers, especially from Neisseria gonorrhoeae and Chlamydia trachomatis. Over the decades, N. gonorrhoeae is alarmingly developing a resistance to most antibiotics currently prescribed. To counter this challenge, it is imperative to find potent and cost-effective therapeutic agents for prophylaxis and treatment, to which the N. gonorrhoeae cannot easily develop resistance. This review showcases alternate therapies such as antimicrobial-fatty acids, -peptides, -nano-formulations etc., currently evident against N. gonorrhoeae-mediated ophthalmia neonatorum, which remains a major cause of ocular morbidity, blindness and even death among neonates in developing countries.

Neisseria gonorrhoeae vaccines: a contemporary overview

Neisseria gonorrhoeae infection is an important public health issue, with an annual global incidence of 87 million. N. gonorrhoeae infection causes significant morbidity and can have serious long-term impacts on reproductive and neonatal health and may rarely cause life-threatening disease. Global rates of N. gonorrhoeae infection have increased over the past 20 years. Importantly, rates of antimicrobial resistance to key antimicrobials also continue to increase, with the United States Centers for Disease Control and Prevention identifying drug-resistant N. gonorrhoeae as an urgent threat to public health. This review summarizes the current evidence for N. gonorrhoeae vaccines, including historical clinical trials, key N. gonorrhoeae vaccine preclinical studies, and studies of the impact of Neisseria meningitidis vaccines on N. gonorrhoeae infection. A comprehensive survey of potential vaccine antigens, including those identified through traditional vaccine immunogenicity approaches, as well as those identified using more contemporary reverse vaccinology approaches, are also described. Finally, the potential epidemiological impacts of a N. gonorrhoeae vaccine and research priorities for further vaccine development are described.

Analytical and clinical validation of a multiplex PCR assay for detection of Neisseria gonorrhoeae and Chlamydia trachomatis including simultaneous LGV serotyping on an automated high-throughput PCR system

For effective infection control measures for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG), a reliable tool for screening and diagnosis is essential. Here, we aimed to establish and validate a multiplex PCR assay on an automated system using a dual-target approach for the detection of CT/NG and differentiation between lymphogranuloma venereum (LGV) and non-LGV from genital and extra-genital specimens. Published primer/probe sets (CT: pmpH, cryptic plasmid; NG: porA, opa) were modified for the cobas 5800/6800/8800. Standards quantified by digital PCR were used to determine linearity and lower limit of detection (LLoD; eSwab, urine). For clinical validation, prospective samples (n = 319) were compared with a CE-marked in vitro diagnostics (CE-IVD) assay. LLoDs ranged from 21.8 to 244 digital copies (dcp)/mL and 10.8 to 277 dcp/mL in swab and urine, respectively. A simple linear regression analysis yielded slopes ranging from -4.338 to -2.834 and Pearson correlation coefficients from 0.956 to 0.994. Inter- and intra-run variability was <0.5 and <1 cycle threshold (ct), respectively. No cross-reactivity was observed (n = 42). Clinical validation showed a sensitivity of 94.74% (95% confidence interval (CI): 87.23%-97.93%) and 95.51% (95% CI: 89.01%-98.24%), a specificity of 99.59% (95% CI: 97.71%-99.98%) and 99.57% (95% CI: 97.58%-99.98%), positive predictive values of 89.91% (estimated prevalence: 3.7%; 95% CI: 80.91%-95.6%) and 88.61% (estimated prevalence: 3.4%; 95% CI: 80.18%-94.34%), and negative predictive values of 99.81% (95% CI: 98.14%-100%) and 99.85% (95% CI: 98.14%-100%) for the detection of CT and NG, respectively. In conclusion, we established a dual-target, internally controlled PCR on an automated system for the detectiwon of CT/NG from genital and extra-genital specimens. Depending on local regulations, the assay can be used as a screening or a confirmatory/typing assay.IMPORTANCEChlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) represent a major global health burden, with the World Health Organization estimating that >128 million and >82 million people, respectively, were newly infected in 2020. For effective infection control measures, a reliable tool for sensitive diagnosis and screening of CT/NG is essential. We established a multiplex PCR assay for the detection of CT/NG and simultaneous discrimination between lymphogranuloma venereum (LGV) and non-LGV strains, which has been validated for genital and extra-genital specimens on a fully automated system. To increase assay sensitivity, a dual-target approach has been chosen for both pathogens. This strategy reduces false-positive results in oropharyngeal swabs due to the detection of commensal N. species that may harbor NG DNA fragments targeted in the PCR due to horizontal gene transmission following previous infection. In sum, the established assay provides a powerful tool for use as either a screening/diagnostic or a typing/confirmatory assay.

The Management of Gonorrhea in the Era of Emerging Antimicrobial Resistance: What Primary Care Clinicians Should Know

Gonorrhea rates continue to rise in the United States and Neisseria gonorrhoeae's propensity to develop resistance to all therapies used for treatment has complicated the management of gonorrhea. Ceftriaxone is the only remaining highly effective recommended regimen for gonococcal treatment and few new anti-gonococcal antimicrobials are being developed. The 2021 CDC STI Treatment Guidelines increased the dose of ceftriaxone to 500 mg (1 g if ≥ 150 kg) for uncomplicated infections. It is recommended that all clinicians should be aware of antimicrobial resistant gonorrhea and be able to appropriately manage any suspected gonorrhea treatment failure case.

Pharmacodynamics of zoliflodacin plus doxycycline combination therapy against Neisseria gonorrhoeae in a gonococcal hollow-fiber infection model

Antimicrobial resistance in the sexually transmitted bacterium Neisseria gonorrhoeae is compromising the management and control of gonorrhea globally. Optimized use and enhanced stewardship of current antimicrobials and development of novel antimicrobials are imperative. The first in class zoliflodacin (spiropyrimidinetrione, DNA Gyrase B inhibitor) is a promising novel antimicrobial in late-stage clinical development for gonorrhea treatment, i.e., the phase III randomized controlled clinical trial (ClinicalTrials.gov Identifier: NCT03959527) was recently finalized, and zoliflodacin showed non-inferiority compared to the recommended ceftriaxone plus azithromycin dual therapy. Doxycycline, the first-line treatment for chlamydia and empiric treatment for non-gonococcal urethritis, will be frequently given together with zoliflodacin because gonorrhea and chlamydia coinfections are common. In a previous static in vitro study, it was indicated that doxycycline/tetracycline inhibited the gonococcal killing of zoliflodacin in 6-h time-kill curve analysis. In this study, our dynamic in vitro hollow-fiber infection model (HFIM) was used to investigate combination therapies with zoliflodacin and doxycycline. Dose-range experiments using the three gonococcal strains WHO F (susceptible to relevant therapeutic antimicrobials), WHO X (extensively drug-resistant, including ceftriaxone-resistant; zoliflodacin-susceptible), and SE600/18 (zoliflodacin-susceptible strain with GyrB S467N substitution) were conducted simulating combination therapy with a single oral dose of zoliflodacin 0.5-4 g combined with a doxycycline daily oral dose of 200 mg administered as 100 mg twice a day, for 7 days (standard dose for chlamydia treatment). Comparing combination therapy of zoliflodacin (0.5-4 g single dose) plus doxycycline (200 mg divided into 100 mg twice a day orally, for 7 days) to zoliflodacin monotherapy (0.5-4 g single dose) showed that combination therapy was slightly more effective than monotherapy in the killing of N. gonorrhoeae and suppressing emergence of zoliflodacin resistance. Accordingly, WHO F was eradicated by only 0.5 g single dose of zoliflodacin in combination with doxycycline, and WHO X and SE600/18 were both eradicated by a 2 g single dose of zoliflodacin in combination with doxycycline; no zoliflodacin-resistant populations occurred during the 7-day experiment when using this zoliflodacin dose. When using suboptimal (0.5-1 g) zoliflodacin doses together with doxycycline, gonococcal mutants with increased zoliflodacin MICs, due to GyrB D429N and the novel GyrB T472P, emerged, but both the mutants had an impaired biofitness. The present study shows the high efficacy of zoliflodacin plus doxycycline combination therapy using a dynamic HFIM that more accurately and comprehensively simulate gonococcal infection and their treatment, i.e., compared to static in vitro models, such as short-time checkerboard experiments or time-kill curve analysis. Based on our dynamic in vitro HFIM work, zoliflodacin plus doxycycline for the treatment of both gonorrhea and chlamydia can be an effective combination.

[Urethritis-spectrum of pathogens, diagnostics and treatment]

A broad spectrum of bacteria, fungi, protozoa and viruses can cause urethritis. In particular, N. gonorrhoeae, C. trachomatis, M. genitalium and T. vaginalis are the focus of diagnostic considerations as classic pathogens associated with sexually transmitted infections (STI). A step-by-step procedure is needed to make a definitive diagnosis. Microscopy with a staining preparation provides an initial differentiation between gonoccocal and non-gonococcal urethritis in symptomatic men as a point-of-care (POC) test. Nucleic acid amplification technology (NAAT) is used for specific and sensitive pathogen detection and, as a multiplex diagnostic test, offers the possibility of detecting several organisms from the same sample. In addition, compared to culture, no vital organisms are required, which allows the collection and use of more diverse and less invasive biological samples (e.g. first stream urine in men or vaginal swabs). Susceptibility testing by culture remains essential for N. gonorrhoeae as resistance is emerging. The treatment of urethritis depends on the suspected or proven pathogen according to the current guidelines. Treatment failure can be caused by many factors (coinfection, lack of therapy adherence, reinfection or resistance of the pathogen) and requires a repeated diagnostic and therapeutic procedure and differentiated approach.

Genomic epidemiology of Neisseria gonorrhoeae in Shenzhen, China, during 2019-2020: increased spread of ceftriaxone-resistant isolates brings insights for strengthening public health responses

The antimicrobial resistance (AMR) in gonorrhea poses global threat of increasing public health concern. In response to this concern, molecular surveillance has been widely utilized to detail the changes in the evolution and distribution of Neisseria gonorrhoeae during AMR transmission. In this study, we performed a comprehensive molecular surveillance of 664 N. gonorrhoeae isolates collected in Shenzhen, one of the cities with the largest mobile population in China, 2019-2020. In 2020, ceftriaxone showed an unprecedented high resistance rate of 24.87%, and 67.83% of the ceftriaxone-resistant (Cro-R) isolates harbored a nonmosaic penA allele. The Cro-R isolates with nonmosaic penA alleles showed a tremendous increasing trend from 0.00% in 2014 to 20.45% in 2020, which proves the need for monitoring nonmosaic penA-related resistance. Importantly, genotyping indicated that multilocus sequence typing ST11231 (35.71%) had a notable rate of ceftriaxone resistance, which might become the focus of future surveillance. Whole-genome sequencing analysis showed that the internationally spreading FC428 clones have circulated in Shenzhen region with typical ceftriaxone resistance (MIC ≥ 0.5 mg/L) maintained. Our surveillance combined with genomic analysis provides current information to update gonorrhea management guidelines and emphasizes that continuous AMR surveillance for N. gonorrhoeae is essential. IMPORTANCE We conducted a comprehensive molecular epidemiology analysis for antimicrobial-resistant Neisseria gonorrhoeae in Shenzhen during 2019-2020, which provided important data for personalized treatment and adjustment of monitoring strategy. Briefly, the proportion of ceftriaxone-resistant (Cro-R) isolates reached a stunning prevalence rate of 24.87% in 2020. A typical increment of Cro-R isolates with nonmosaic penA alleles proves the necessity of monitoring nonmosaic AMR mechanism and involving it into developing molecular detection methods. Whole-genome sequencing analysis showed that the international spreading FC428 clone has been circulating in Shenzhen with typical ceftriaxone resistance (MIC ≥ 0.5 mg/L) maintained. In summary, we conducted a comprehensive epidemiology study, providing significant data for therapy management. Our results not only improve the understanding of the distribution and transmission of AMR in N. gonorrhoeae but also provide effective AMR data for improving surveillance strategies in China.

Rapid expansion of Neisseria gonorrhoeae ST7827 clone in Australia, with variable ceftriaxone phenotype unexplained by genotype

BACKGROUND

Neisseria gonorrhoeae is identified as a priority pathogen due to its capacity to rapidly develop antimicrobial resistance (AMR). Following the easing of SARS-CoV-2 pandemic travel restrictions across international borders in the state of New South Wales (NSW), Australia, a surge of gonococcal isolates with raised ceftriaxone MIC values were detected.

METHODS

All N. gonorrhoeae isolates (n = 150) with increased ceftriaxone MIC values in NSW between 1 January 2021 and July 2022 from males and females from all sites were sequenced.

RESULTS

A new emergence and rapid expansion of an N. gonorrhoeae ST7827 clone was documented within NSW, Australia and provides further evidence of the ability of N. gonorrhoeae to undergo sufficient genomic changes and re-emerge as a geographically restricted subclone. Mapping AMR determinants to MIC results did not reveal any genomic pattern that correlated with MIC values.

CONCLUSIONS

The rapid dissemination and establishment of this clone at the population level is a new and concerning demonstration of the agility of this pathogen, and underscores concerns about similar incursions and establishment of MDR clones. Moreover, it is notable that in this context the AMR genotype-phenotype correlates remain unclear, which requires further investigation to enable better understanding of genomic aspects of AMR in N. gonorrhoeae.

Two cases of extensively drug-resistant (XDR) Neisseria gonorrhoeae infection combining ceftriaxone-resistance and high-level azithromycin resistance, France, November 2022 and May 2023

We report two extensively drug-resistant (XDR) Neisseria gonorrhoeae (NG) isolates combining high-level resistance to azithromycin and resistance to ceftriaxone, obtained in France from two heterosexual patients, one of whom returned from Cambodia. Whole genome sequencing identified MLST ST16406, the mosaic penA-60.001 which caused ceftriaxone resistance in the internationally spreading FC428 clone, and the A2059G mutation in the 23S rRNA gene. The NG isolates F93 and F94 were related to XDR isolates detected in Austria and the United Kingdom in 2022.

High-level in vitro resistance to gentamicin acquired in a stepwise manner in Neisseria gonorrhoeae

OBJECTIVES

Gentamicin is used in several alternative treatments for gonorrhoea. Verified clinical Neisseria gonorrhoeae isolates with gentamicin resistance are mainly lacking and understanding the mechanisms for gonococcal gentamicin resistance is imperative. We selected gentamicin resistance in gonococci in vitro, identified the novel gentamicin-resistance mutations, and examined the biofitness of a high-level gentamicin-resistant mutant.

METHODS

Low- and high-level gentamicin resistance was selected in WHO X (gentamicin MIC = 4 mg/L) on gentamicin-gradient agar plates. Selected mutants were whole-genome sequenced. Potential gentamicin-resistance fusA mutations were transformed into WT strains to verify their impact on gentamicin MICs. The biofitness of high-level gentamicin-resistant mutants was examined using a competitive assay in a hollow-fibre infection model.

RESULTS

WHO X mutants with gentamicin MICs of up to 128 mg/L were selected. Primarily selected fusA mutations were further investigated, and fusAR635L and fusAM520I + R635L were particularly interesting. Different mutations in fusA and ubiM were found in low-level gentamicin-resistant mutants, while fusAM520I was associated with high-level gentamicin resistance. Protein structure predictions showed that fusAM520I is located in domain IV of the elongation factor-G (EF-G). The high-level gentamicin-resistant WHO X mutant was outcompeted by the gentamicin-susceptible WHO X parental strain, suggesting lower biofitness.

CONCLUSIONS

We describe the first high-level gentamicin-resistant gonococcal isolate (MIC = 128 mg/L), which was selected in vitro through experimental evolution. The most substantial increases of the gentamicin MICs were caused by mutations in fusA (G1560A and G1904T encoding EF-G M520I and R635L, respectively) and ubiM (D186N). The high-level gentamicin-resistant N. gonorrhoeae mutant showed impaired biofitness.

Enhancing Insights into Australia's Gonococcal Surveillance Programme through Stochastic Modelling

Continued surveillance of antimicrobial resistance is critical as a feedback mechanism for the generation of concerted public health action. A characteristic of importance in evaluating disease surveillance systems is representativeness. Scenario tree modelling offers an approach to quantify system representativeness. This paper utilises the modelling approach to assess the Australian Gonococcal Surveillance Programme's representativeness as a case study. The model was built by identifying the sequence of events necessary for surveillance output generation through expert consultation and literature review. A scenario tree model was developed encompassing 16 dichotomous branches representing individual system sub-components. Key classifications included biological sex, clinical symptom status, and location of healthcare service access. The expected sensitivities for gonococcal detection and antibiotic status ascertainment were 0.624 (95% CI; 0.524, 0.736) and 0.144 (95% CI; 0.106, 0.189), respectively. Detection capacity of the system was observed to be high overall. The stochastic modelling approach has highlighted the need to consider differential risk factors such as sex, health-seeking behaviours, and clinical behaviour in sample generation. Actionable points generated by this study include modification of clinician behaviour and supplementary systems to achieve a greater contextual understanding of the surveillance data generation process.

Current State of Knowledge Regarding WHO High Priority Pathogens-Resistance Mechanisms and Proposed Solutions through Candidates Such as Essential Oils: A Systematic Review

Combating antimicrobial resistance (AMR) is among the 10 global health issues identified by the World Health Organization (WHO) in 2021. While AMR is a naturally occurring process, the inappropriate use of antibiotics in different settings and legislative gaps has led to its rapid progression. As a result, AMR has grown into a serious global menace that impacts not only humans but also animals and, ultimately, the entire environment. Thus, effective prophylactic measures, as well as more potent and non-toxic antimicrobial agents, are pressingly needed. The antimicrobial activity of essential oils (EOs) is supported by consistent research in the field. Although EOs have been used for centuries, they are newcomers when it comes to managing infections in clinical settings; it is mainly because methodological settings are largely non-overlapping and there are insufficient data regarding EOs' in vivo activity and toxicity. This review considers the concept of AMR and its main determinants, the modality by which the issue has been globally addressed and the potential of EOs as alternative or auxiliary therapy. The focus is shifted towards the pathogenesis, mechanism of resistance and activity of several EOs against the six high priority pathogens listed by WHO in 2017, for which new therapeutic solutions are pressingly required.

Antimicrobial resistance of Neisseria gonorrhoeae in Latin American countries: a systematic review

BACKGROUND

Detailed information is needed on the dynamic pattern of antimicrobial resistance (AMR) in Neisseria gonorrhoeae in Latin America and the Caribbean (LAC).

OBJECTIVES

To conduct a systematic review of AMR in N. gonorrhoeae in LAC.

METHODS

Electronic searches without language restrictions were conducted in PubMed, Embase, Cochrane Library, EconLIT, Cumulative Index of Nursing and Allied Health Literature, Centre for Reviews and Dissemination, and Latin American and Caribbean Literature in Health Sciences. Studies were eligible if published between 1 January 2011 and 13 February 2021, conducted in any LAC country (regardless of age, sex and population) and measured frequency and/or patterns of AMR to any antimicrobial in N. gonorrhoeae. The WHO Global Gonococcal Antimicrobial Surveillance Programme (WHO-GASP) for LAC countries and Latin American AMR SurveillanceNetwork databases were searched. AMR study quality was evaluated according to WHO recommendations.

RESULTS

AMR data for 38, 417 isolates collected in 1990-2018 were included from 31 publications, reporting data from Argentina, Brazil, Colombia, Peru, Uruguay, Venezuela and WHO-GASP. Resistance to extended-spectrum cephalosporins was infrequent (0.09%-8.5%). Resistance to azithromycin was up to 32% in the published studies and up to 61% in WHO-GASP. Resistance to penicillin, tetracycline and ciprofloxacin was high (17.6%-98%, 20.7%-90% and 5.9%-89%, respectively). Resistance to gentamicin was not reported, and resistance to spectinomycin was reported in one study.

CONCLUSIONS

This review provides data on resistance to azithromycin, potentially important given its use as first-line empirical treatment, and indicates the need for improved surveillance of gonococcal AMR in LAC. Trial registration: Registered in PROSPERO, CRD42021253342.

Dissemination of Neisseria gonorrhoeae with decreased susceptibility to extended-spectrum cephalosporins in Southern China, 2021: a genome-wide surveillance from 20 cities

BACKGROUND

Antimicrobial resistance (AMR) of untreatable gonococcal infection is an emerging threat, especially in Guangdong, a prosperous province in Southern China.

METHODS

N.gonorrhoeae was isolated from 20 cities in Guangdong and determined antimicrobial susceptibility. Through whole-genome sequencing (WGS), multilocus sequence typing (MLST), N.gonorrhoeae multiantigen sequence typing (NG-MAST), and N.gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) were obtained based on the PubMLST database ( https://pubmlst.org/ ). Phylogenetic analysis was used for dissemination and tracking analysis.

RESULTS

Antimicrobial susceptibility was performed on 347 isolates, and 50 isolates were identified as decreased susceptibility (DS) to cephalosporins. Of which 16.0% (8/50) were ceftriaxone DS, 38.0% (19/50) were cefixime DS, and 46.0% (23/50) were both ceftriaxone and cefixime DS. In all, the dual-resistant rate of the cephalosporin-DS isolates was 96.0% for penicillin and 98.0% for tetracycline-resistant, and 10.0% (5/50) were resistant to azithromycin. All cephalosporin-DS isolates were resistant to ciprofloxacin but sensitive to spectinomycin. The predominant MLSTs were ST7363 (16%, 8/50), ST1903 (14%, 7/50), ST1901 (12%, 6/50), and ST7365 (10%, 5/50). Besides some isolates that failed genotyping (NA), NG-STAR ST1143 (n = 6) and NG-MAST ST17748 (n = 4) were the most prevalent. Twelve isolates with mosaic penA-60.001 allele retained the most elevated cephalosporin MIC (Minimum Inhibitory Concentration). Phylogenetic analysis revealed that epidemic penA-60.001 clones, either domestic or foreign, had spread to nine cities in Guangdong, and 9/12 clones were from the Pearl River Delta region.

CONCLUSIONS

N. gonorrhoeae with cephalosporins-DS was extensively disseminated in Guangdong, Southern China, requiring strict surveillance.

Rapid Molecular Phenotypic Antimicrobial Susceptibility Test for Neisseria gonorrhoeae Based on Propidium Monoazide Viability PCR

Neisseria gonorrhoeae (NG) is an urgent threat to antimicrobial resistance (AMR) worldwide. NG has acquired rapid resistance to all previously recommended treatments, leaving ceftriaxone monotherapy as the first and last line of therapy for uncomplicated NG. The ability to rapidly determine susceptibility, which is currently nonexistent for NG, has been proposed as a strategy to preserve ceftriaxone by using alternative treatments. Herein, we used a DNA-intercalating dye in combination with NG-specific primers/probes to generate qPCR cycle threshold (Ct) values at different concentrations of 2 NG-relevant antimicrobials. Our proof-of-concept dual-antimicrobial logistic regression model based on the differential Ct measurements achieved an AUC of 0.93 with a categorical agreement for the susceptibility of 84.6%. When surveying the performance against each antimicrobial separately, the model predicted 90 and 75% susceptible and resistant strains, respectively, to ceftriaxone and 66.7 and 83.3% susceptible and resistant strains, respectively, to ciprofloxacin. We further validated the model against the individual replicates and determined the accuracy of the model in classifying susceptibility agnostic of the inoculum size. We demonstrated a novel PCR-based approach to determine phenotypic ciprofloxacin and ceftriaxone susceptibility information for NG with reasonable accuracy within 30 min, a significant improvement compared to the conventional method which could take multiple days.

An open-label randomised controlled trial evaluating the efficacy of a meningococcal serogroup B (4CMenB) vaccine on Neisseria gonorrhoeae infection in gay and bisexual men: the MenGO study protocol

BACKGROUND

Gonorrhoea is an ongoing public health concern due to its rising incidence and the emergence of antibiotic resistance. There are an estimated 82 million new Neisseria gonorrhoeae infections each year, with several populations at higher risk for gonococcal infection, including gay and bisexual men (GBM). If left untreated, infection can lead to serious morbidity including infertility, sepsis and increased risk of HIV acquisition. Development of a gonorrhoea vaccine has been challenging, however there is observational evidence that serogroup B meningococcal vaccines, used to protect against the closely related bacteria Neisseria meningitidis, could provide cross-protection against N. gonorrhoeae.

METHODS

The MenGO (Meningococcal vaccine efficacy against Gonorrhoea) study is a phase III open-label randomised control trial in GBM to evaluate the efficacy of the four-component meningococcal serogroup B vaccine, 4CMenB, against gonorrhoea. A total of 130 GBM will be recruited at the Gold Coast Sexual Health Clinic, Australia, and randomised to either receive 2 doses of 4CMenB or no intervention. Participants will be followed up for 24 months with testing for N. gonorrhoeae and other sexually transmissible infections every three months. Demographics, sexual behaviour risk, antibiotic use, and blood samples for analysis of N. gonorrhoeae-specific immune responses, will be collected during the study. The primary outcome is the number of N. gonorrhoeae infections in participants over 2 years measured by nucleic acid amplification test (NAAT). Secondary outcomes are vaccine-induced N. gonorrhoeae-specific immune responses, and adverse events in trial participants.

DISCUSSION

This trial will determine if the 4CMenB vaccine is able to reduce N. gonorrhoeae infection. If shown to be effective, 4CMenB could be used in gonococcal prevention. Analysis of 4CMenB-induced immune responses will increase understanding of the type of immune response needed to prevent N. gonorrhoeae, which may enable identification of a potential correlate of protection to aid future gonorrhoea vaccine development.

TRIAL REGISTRATION

The trial has been registered on the Australian and New Zealand Clinical Trials Registry (ACTRN12619001478101) on 25 October 2019.

Rapid molecular phenotypic antimicrobial susceptibility test for Neisseria gonorrhoeae based on propidium monoazide viability PCR

Neisseria gonorrhoeae (NG) is an urgent threat to antimicrobial resistance (AMR) worldwide. NG has acquired rapid resistance to all previously recommended treatments leaving ceftriaxone monotherapy as the first and last line of therapy for uncomplicated NG. The ability to rapidly determine susceptibility, which is currently nonexistent for NG, has been proposed as a strategy to preserve ceftriaxone by using alternative treatments. Herein, we used a DNA-intercalating dye in combination with NG-specific primers/probes to generate qPCR cycle threshold (Ct) values at different concentrations of 2 NG-relevant antimicrobials. Our proof of concept dual-antimicrobial logistic regression model based on the differential Ct measurements achieved an AUC of 0.93 with a categorical agreement for susceptibility of 84.6%. When surveying the performance against each antimicrobial separately, the model predicted 90% and 75% susceptible and resistant strains respectively to ceftriaxone and 66.7% and 83.3% susceptible and resistant strains respectively to ciprofloxacin. We further validated the model against the individual replicates and determined the accuracy of the model in classifying susceptibility agnostic of the inoculum size. We demonstrated a novel PCR-based approach to determine phenotypic ciprofloxacin and ceftriaxone susceptibility information for NG with reasonable accuracy in under 30 min, a significant improvement compared to the conventional method which takes 3 days.

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Repurposing Carbamazepine To Treat Gonococcal Infection in Women: Oral Delivery for Control of Epilepsy Generates Therapeutically Effective Levels in Vaginal Secretions

Neisseria gonorrhoeae has developed resistance to all previous antibiotics used for treatment. This highlights a crucial need for novel antimicrobials to treat gonococcal infections. We previously showed that carbamazepine (Cz), one of the most commonly prescribed antiepileptic drugs, can block the interaction between gonococcal pili and the I-domain region of human complement receptor 3 (CR3)-an interaction that is vital for infection of the female cervix. We also show that Cz can completely clear an established N. gonorrhoeae infection of primary human cervical cells. In this study, we quantified Cz in serum, saliva, and vaginal fluid collected from 16 women who were, or were not, regularly taking Cz. We detected Cz in lower reproductive tract mucosal secretions in the test group (women taking Cz) at potentially therapeutic levels using a competitive ELISA. Furthermore, we found that Cz concentrations present in vaginal fluid from women taking this drug were sufficient to result in a greater than 99% reduction (within 24 h) in the number of viable gonococci recovered from ex vivo, human, primary cervical cell infections. These data provide strong support for the further development of Cz as a novel, host-targeted therapy to treat gonococcal cervicitis.

Emergence and Genomic Characterization of Neisseria gonorrhoeae Isolates with High Levels of Ceftriaxone and Azithromycin Resistance in Guangdong, China, from 2016 to 2019

Currently, antibiotic resistance (especially ceftriaxone and azithromycin dual resistance) in Neisseria gonorrhoeae is the main obstacle affecting the efficacy of treatment. As analysis of drug sensitivity, molecular features, and dissemination of dual-resistant strains is important for gonococcal prevention and control, MIC, genotyping, and genome analysis were conducted to reveal the molecular characteristics and phylogeny of N. gonorrhoeae isolates. During 2016 to 2019, 5 out of 4,113 strains were defined as dual-resistant clones, with ceftriaxone MICs of 0.25 to ≥1 mg/L and azithromycin MICs of 2 to ≥2,048 mg/L. In particular, two strains with a ceftriaxone MIC above 0.5 mg/L were characterized as penA-60.001 FC428-related clones, and two isolates with a high-level azithromycin MIC above 1,024 mg/L featuring a 23S rRNA mutation were identified. Furthermore, phylogenetic analysis confirmed that the dual-resistant strains were closer to the evolutionary origin of F89 in France, global FC428-related clones, and high-level dual-resistant clones in Australia and the United Kingdom. Dual-resistant strains, including FC428-related clones and high-level azithromycin-resistant clones, have circulated in Guangdong, China. The ability of laboratories to perform real-time drug susceptibility and genetic analyses should be strengthened to monitor the spread of threatening strains. IMPORTANCE Here, we report five sporadic dual-resistant isolates, including FC428-related ceftriaxone-resistant clones with MICs of ≥0.5 mg/L and high-level azithromycin resistance with MICs of ≥1,024 mg/L. This study highlights that dual-resistant clones with the same evolutionary origin as FC428, A2735, and F89 have circulated in Guangdong, China, which suggests that the capacity for antibiotic resistance testing and genome analysis should be strengthened in daily epidemiological surveillance.

Current Susceptibility Surveillance and Distribution of Antimicrobial Resistance in N. gonorrheae within WHO Regions

Neisseria gonorrhoeae (N. gonorrhoeae) is the etiological agent of the second most common sexually transmitted disease in the world, gonorrhoea. Currently recommended and last available first-line therapy is extended-spectrum cephalosporins most often combined with azitromycin. However, misuse of antibiotics and the abilities of N. gonorrhoeae to acquire new genetic and plasmid-borne resistance determinants has gradually led to the situation where this bacterium has become resistant to all major classes of antibiotics. Together with a generally slow update of treatment guidelines globally, as well as with the high capacity of gonococci to develop and retain AMR, this may lead to the global worsening of gonococcal AMR. Since effective vaccines are unavailable, the management of gonorrhoea relies mostly on prevention and accurate diagnosis, together with antimicrobial treatment. The study overviews the latest results of mostly WHO-initiated studies, primarily focusing on the data regarding the molecular basis of the resistance to the current and novel most promising antibacterial agents, which could serve to establish or reinforce the continual, quality-assured and comparable AMR surveillance, including systematic monitoring and treatment with the use of molecular AMR prediction methods.

Molecular Mechanisms of Drug Resistance and Epidemiology of Multidrug-Resistant Variants of Neisseria gonorrhoeae

The paper presents various issues related to the increasing drug resistance of Neisseria gonorrhoeae and the occurrence and spread of multidrug-resistant clones. One of the most important is the incidence and evolution of resistance mechanisms of N. gonorrhoeae to beta-lactam antibiotics. Chromosomal resistance to penicillins and oxyimino-cephalosporins and plasmid resistance to penicillins are discussed. Chromosomal resistance is associated with the presence of mutations in the PBP2 protein, containing mosaic variants and nonmosaic amino acid substitutions in the transpeptidase domain, and their correlation with mutations in the mtrR gene and its promoter regions (the MtrCDE membrane pump repressor) and in several other genes, which together determine reduced sensitivity or resistance to ceftriaxone and cefixime. Plasmid resistance to penicillins results from the production of beta-lactamases. There are different types of beta-lactamases as well as penicillinase plasmids. In addition to resistance to beta-lactam antibiotics, the paper covers the mechanisms and occurrence of resistance to macrolides (azithromycin), fluoroquinolones and some other antibiotics. Moreover, the most important epidemiological types of multidrug-resistant N. gonorrhoeae, prevalent in specific years and regions, are discussed. Epidemiological types are defined as sequence types, clonal complexes and genogroups obtained by various typing systems such as NG-STAR, NG-MAST and MLST. New perspectives on the treatment of N. gonorrhoeae infections are also presented, including new drugs active against multidrug-resistant strains.

Sexually Transmitted Infections Among Men and Transgender Women Using HIV Pre-exposure Prophylaxis in a Large Integrated Health System-A Cohort Study

BACKGROUND

Sexually transmitted infections (STIs) are common in people using pre-exposure prophylaxis (PrEP). We examined risk and factors associated with STIs in a cohort of PrEP users in an integrated health system in the United States.

SETTING

The Kaiser Permanente Southern California is a large integrated health system that provides comprehensive medical services to approximately 4.7 million demographically diverse members.

METHODS

We identified men and transgender women initiating PrEP between January 1, 2014, and June 1, 2018, and followed through December 31, 2018. Demographic and clinical factors potentially associated with the risk of bacterial STIs during PrEP use were evaluated using Poisson regression models.

RESULTS

Among 5042 individuals tested for STIs with 7198 person-years of follow-up, 1709 (33.9%) had at least one new STI. The estimated incidence of STIs was 48.3 per 100 person-years, and the most common STI was rectal chlamydia. Most repeat STIs (61.4%) occurred <180 days apart. In a multivariable analysis, an history of STIs in the prior 6 months through 7 days after the PrEP initiation was the most prominent risk factor of STIs during PrEP use (adjusted risk ratio: 1.78, 95% confidence intervals: 1.65 to 1.93). Other risk factors included younger age (<35 years), being Hispanic, and having a history of alcohol use disorder or drug use disorder.

CONCLUSIONS

Quarterly STI testing and targeted intervention to mitigate STI risk are warranted for young and racial minority PrEP users, particularly for those with prior history of STIs and substance use disorders.

Etiological Surveillance of Male Urethritis Syndrome in South Africa: 2019 to 2020

BACKGROUND

In South Africa, male urethritis syndrome (MUS) is the most common sexually transmitted infection (STI) syndrome in men. We determined the distribution of STI etiologies and the susceptibility profiles of Neisseria gonorrhoeae isolates from men presenting with MUS to 3 sentinel surveillance health care facilities. Secondary objectives were to determine the seroprevalence of coinfections (HIV, syphilis, herpes simplex virus 2).

METHODS

Consecutive, consenting men with symptomatic urethral discharge were enrolled between January 1, 2019, and December 31, 2020. Genital discharge swab and blood specimens were collected and transported to a central STI reference laboratory in Johannesburg, South Africa.

RESULTS

Among 769 men enrolled, N. gonorrhoeae was the commonest cause of MUS (674 [87.8%]; 95% confidence interval [CI], 85.2%-89.9%), followed by Chlamydia trachomatis (161 [21.0%]; 95% CI, 18.2%-24.0%). Of 542 cultivable N. gonorrhoeae isolates, all were susceptible to ceftriaxone (modal minimum inhibitory concentration, 0.004 mg/L) and azithromycin (modal minimum inhibitory concentration, 0.128 mg/L). Seroprevalence rates of HIV, syphilis, and HSV-2 were 21.4% (95% CI, 18.5%-24.5%), 2.3%, and 50.1%, respectively. Condom use at last sexual encounter was reported by only 7%, less than 50% had been medically circumcised, and only 66.7% (58 of 87) who self-reported an HIV-positive status were adherent on antiretroviral drugs.

CONCLUSIONS

Neisseria gonorrhoeae and C. trachomatis were the predominant causes of MUS. Currently recommended dual ceftriaxone and azithromycin therapy are appropriate for MUS syndromic management; however, surveillance must be maintained to timeously detect emerging and increasing gonococcal resistance. Clinic-based interventions must be intensified in men seeing sexual health care to reduce the community transmission and burden of STI and HIV.

Trends and regional variations of gonococcal antimicrobial resistance in the Netherlands, 2013 to 2019

Background

Gonococcal antimicrobial resistance is emerging worldwide and is monitored in the Netherlands in 18 of 24 Sexual Health Centres (SHC).

Aim

To report trends, predictors and regional variation of gonococcal azithromycin resistance (AZI-R, minimum inhibitory concentration (MIC) > 1 mg/L) and ceftriaxone decreased susceptibility (CEF-DS, MIC > 0.032 mg/L) in 2013–2019.

Methods

SHC reported data on individual characteristics, sexually transmitted infection diagnoses, and susceptibility testing (MIC, measured by Etest). We used multilevel logistic regression analysis to identify AZI-R/CEF-DS predictors, correcting for SHC region. Population differences’ effect on regional variance of AZI-R and CEF-DS was assessed with a separate multilevel model.

Results

The study included 13,172 isolates, predominantly (n = 9,751; 74%) from men who have sex with men (MSM). Between 2013 and 2019, annual proportions of AZI-R isolates appeared to increase from 2.8% (37/1,304) to 9.3% (210/2,264), while those of CEF-DS seemed to decrease from 7.0% (91/1,306) to 2.9% (65/2,276). Among SHC regions, 0.0‒16.9% isolates were AZI-R and 0.0−7.0% CEF-DS; population characteristics could not explain regional variance. Pharyngeal strain origin and consultation year were significantly associated with AZI-R and CEF-DS for MSM, women, and heterosexual men. Among women and heterosexual men ≥ 4 partners was associated with CEF-DS, and ≥ 10 with AZI-R.

Conclusions

No resistance or decreasing susceptibility was found for CEF, the first line gonorrhoea treatment in the Netherlands. Similar to trends worldwide, AZI-R appeared to increase. Regional differences between SHC support nationwide surveillance with regional-level reporting. The increased risk of resistance/decreased susceptibility in pharyngeal strains underlines the importance of including extragenital infections in gonococcal resistance surveillance.

Novel small molecules that increase the susceptibility of Neisseria gonorrhoeae to cationic antimicrobial peptides by inhibiting lipid A phosphoethanolamine transferase

Objectives

Neisseria gonorrhoeae is an exclusively human pathogen that commonly infects the urogenital tract resulting in gonorrhoea. Empirical treatment of gonorrhoea with antibiotics has led to multidrug resistance and the need for new therapeutics. Inactivation of lipooligosaccharide phosphoethanolamine transferase A (EptA), which attaches phosphoethanolamine to lipid A, results in attenuation of the pathogen in infection models. Small molecules that inhibit EptA are predicted to enhance natural clearance of gonococci via the human innate immune response.

Methods

A library of small-fragment compounds was tested for the ability to enhance susceptibility of the reference strain N. gonorrhoeae FA1090 to polymyxin B. The effect of these compounds on lipid A synthesis and viability in models of infection were tested.

Results

Three compounds, 135, 136 and 137, enhanced susceptibility of strain FA1090 to polymyxin B by 4-fold. Pre-treatment of bacterial cells with all three compounds resulted in enhanced killing by macrophages. Only lipid A from bacterial cells exposed to compound 137 showed a 17% reduction in the level of decoration of lipid A with phosphoethanolamine by MALDI-TOF MS analysis and reduced stimulation of cytokine responses in THP-1 cells. Binding of 137 occurred with higher affinity to purified EptA than the starting material, as determined by 1D saturation transfer difference NMR. Treatment of eight MDR strains with 137 increased susceptibility to polymyxin B in all cases.

Conclusions

Small molecules have been designed that bind to EptA, inhibit addition of phosphoethanolamine to lipid A and can sensitize N. gonorrhoeae to killing by macrophages.

The European response to control and manage multi- and extensively drug-resistant Neisseria gonorrhoeae

Because cefixime and ceftriaxone resistance in Neisseria gonorrhoeae and gonorrhoea treatment failures were increasing, a response plan to control and manage multidrug-resistant N. gonorrhoeae (MDR-NG) in Europe was published in 2012. The three main areas of the plan were to: (i) strengthen surveillance of antimicrobial resistance (AMR), (ii) implement monitoring of treatment failures and (iii) establish a communication strategy to increase awareness and disseminate AMR results. Since 2012, several additional extensively drug-resistant N. gonorrhoeae (XDR-NG) strains have emerged, and strains with high-level ceftriaxone resistance spread internationally. This prompted an evaluation and review of the 2012 European Centre for Disease Prevention and Control (ECDC) response plan, revealing an overall improvement in many aspects of monitoring AMR in N. gonorrhoeae; however, treatment failure monitoring was a weakness. Accordingly, the plan was updated in 2019 to further support European Union/European Economic Area (EU/EEA) countries in controlling and managing the threat of MDR/XDR-NG in Europe through further strengthening of AMR surveillance and clinical management including treatment failure monitoring. The plan will be assessed biennially to ensure its effectiveness and its value. Along with prevention, diagnostic, treatment and epidemiological surveillance strategies, AMR surveillance is essential for effective control of gonorrhoea.

A case of refractory urethritis with repeated doctor shopping

INTRODUCTION

In the field of sexually transmitted diseases, resistance and diversification of causative organisms are becoming a problem. We report a case in which the course of the disease was complicated by doctor shopping.

CASE PRESENTATION

A man in his 40s visited his local doctor for painful urination and cloudy urine. Due to the lack of improvement in symptoms after antibiotic treatment, he self-selected to visit six hospitals in just five months. He visited our clinic only a few times and then stopped coming.

CONCLUSION

Doctor shopping, as well as self-diagnosis and self-treatment, will continue to increase. Patient education is important, but medical professionals also need to be aware of the possibility of doctor shopping when treating patients.

Increasing azithromycin resistance in Neisseria gonorrhoeae due to NG-MAST 12302 clonal spread in Canada, 2015-2018

Objectives: Azithromycin resistant (AZIR) gonorrhea has been steadily increasing in Canada over the past decade which is cause for alarm as azithromycin (AZI) has been part of the combination therapy recommended by the Canadian Guidelines on Sexually Transmitted Infections (CGSTI) since 2012.

Method: Neisseria gonorrhoeae (NG) with AZI MICs ≥ 1 mg/L collected between 2015 and 2018 as part of the Gonococcal Antimicrobial Surveillance Program-Canada underwent antimicrobial susceptibility testing, molecular typing and whole genome sequencing. Regional, demographic and clinical isolation site comparisons were made to aid in our understanding of AZI susceptibility trending.

Results: 3,447 NG with AZI MICs ≥ 1 mg/L were identified in Canada, increasing from 6.3% in 2015 to 26.5% of isolates in 2018. Central Canada had the highest proportion rising from 9.2% in 2015 to 31.2% in 2018. 273 different NG-MAST sequence types were identified among these isolates with ST-12302 the most prevalent (50.9%). Whole genome sequencing identified the Neisseria lactamica -like mosaic mtr locus as the mechanism of AZIR in isolates of ST-12302 and isolates genetically similar (differ by ≤ 5 base pairs) designated as the ST-12302 genogroup, accounting for 65.2% of study isolateswhich were originally identified in central Canada but spread to other regions by 2018.

Conclusion: Genomic analysis indicated that AZIR in Canadian NG expanded rapidly due to clonal spread of the ST-12302 genogroup. The rapid expansion of this AZIR clonal group in all regions of Canada is of concern. CGSTI are currently under review to address the increase in AZIR in Canada.

A gonococcal vaccine has the potential to rapidly reduce the incidence of Neisseria gonorrhoeae infection among urban men who have sex with men

Background

A gonococcal vaccine is urgently needed due to increasing gonorrhea incidence and emerging multidrug-resistant gonococcal strains worldwide. Men who have sex with men (MSM) have among the highest incidences of gonorrhea and may be a key target population for vaccination when available.

Methods

An individual-based, anatomical site-specific mathematical model was used to simulate Neisseria gonorrhoeae transmission in a population of 10 000 MSM. The impact of vaccination on gonorrhea prevalence was assessed.

Results

With a gonococcal vaccine of 100% or 50% protective efficacy, gonorrhea prevalence could be reduced by 94% or 62%, respectively, within 2 years if 30% of MSM are vaccinated on presentation for sexually transmitted infection (STI) testing. Elimination of gonorrhea is possible within 8 years with vaccines of ≥ 50% efficacy lasting 2 years, providing a booster vaccination is available every 3 years on average. A vaccine’s impact may be reduced if it is not effective at all anatomical sites.

Conclusions

Our study indicates that with a vaccine of modest efficacy and an immunization strategy that targets MSM presenting for STI screening, the prevalence of gonorrhea in this population could be rapidly and substantially reduced.

Development and application of Cas13a-based diagnostic assay for Neisseria gonorrhoeae detection and azithromycin resistance identification

BACKGROUND

Gonorrhoea, caused by Neisseria gonorrhoeae, has spread worldwide. Strains resistant to most antibiotics, including ceftriaxone and azithromycin, have emerged to an alarming level. Rapid testing for N. gonorrhoeae and its antimicrobial resistance will therefore contribute to clinical decision making for early diagnosis and rational drug use.

METHODS

A Cas13a-based assay (specific high-sensitivity enzymatic reporter unlocking; SHERLOCK) was developed for N. gonorrhoeae detection (porA gene) and azithromycin resistance identification (A2059G, C2611T). Assays were evaluated for sensitivity with purified dsDNA and specificity with 17 non-gonococcal strains. Performance of SHERLOCK (porA) was compared with Roche Cobas 4800 using 43 urine samples. Identification of azithromycin resistance mutations (A2059G, C2611T) was evaluated using a total of 84 clinical isolates and 18 urine samples. Lateral flow was tested for this assay as a readout tool. Moreover, we directly assayed 27 urethral swabs from patients with urethritis to evaluate their status in terms of N. gonorrhoeae infection and azithromycin resistance.

RESULTS

The SHERLOCK assay was successfully developed with a sensitivity of 10 copies/reaction, except 100 copies/reaction for A2059G, and no cross-reaction with other species. Comparison of the SHERLOCK assay with the Cobas 4800 revealed 100% concordance within 18 positive and 25 negative urine samples. Of the 84 isolates, 21 strains with azithromycin resistance mutations were distinguished and further verified by sequencing and MIC determination. In addition, 62.96% (17/27) strains from swab samples were detected with no mutant strains confirmed by sequencing.

CONCLUSIONS

The SHERLOCK assay for rapid N. gonorrhoeae detection combined with azithromycin resistance testing is a promising method for application in clinical practice.

Novel strategies for prevention and treatment of antimicrobial resistance in sexually-transmitted infections

PURPOSE OF REVIEW

Antimicrobial resistance in sexually acquired infection (STI) pathogens is an important global public health threat. There is an urgent need for novel STI treatment and prevention strategies to tackle the rising incidence of STIs in high-income settings and the static progress in low- and middle-income settings over the past decade. The purpose of this review was to describe the research outlining the emergence of resistance in common STI pathogens and new strategies for their treatment and prevention.

RECENT FINDINGS

Rates of STIs have dramatically increased over the past decade. Further, antimicrobial resistance to first-line agents among key STI pathogens continues to emerge globally. Recent findings demonstrate promising results regarding the efficacy of novel antimicrobial treatment strategies for these pathogens, including several new, repurposed and unique combinations of antimicrobials. In addition, a number of new biomedical prevention strategies, such as antibacterial mouthwash and doxycycline chemoprophylaxis, are being investigated as novel prevention strategies for bacterial STIs.

SUMMARY

Significant progress has been made in the development of novel antimicrobials for the treatment of antimicrobial-resistant sexually acquired pathogens. However, due to the rapid development of resistance to antimicrobials demonstrated by these pathogens in the past, further research and development of effective prevention strategies should be prioritized.

Hydrogel Droplet Microarray for Genotyping Antimicrobial Resistance Determinants in Neisseria gonorrhoeae Isolates

A multiplex assay based on a low-density hydrogel microarray was developed to identify genomic substitutions in N. gonorrhoeae that determine resistance to the currently recommended treatment agents ceftriaxone and azithromycin and the previously used drugs penicillin, tetracycline, and ciprofloxacin. The microarray identifies 74 drug resistance determinants in the N. gonorrhoeae penA, ponA, porB, gyrA, parC, rpsJ, mtrR, bla_TEM, tetM, and 23S rRNA genes. The hydrogel elements were formed by automated dispensing of nanoliter-volume droplets followed by UV-induced copolymerization of NH₂-containing oligonucleotides with gel-forming monomers. Polybutylene terephthalate plates without special modifications were used as microarray substrates. Sequences and concentrations of immobilized oligonucleotides, gel composition, and hybridization conditions were carefully selected, and the median discrimination ratio ranged from 2.8 to 29.4, allowing unambiguous identification of single-nucleotide substitutions. The mutation identification results in a control sample of 180 N. gonorrhoeae isolates were completely consistent with the Sanger sequencing results. In total, 648 clinical N. gonorrhoeae isolates obtained in Russia during the last 5 years were analyzed and genotyped using these microarrays. The results allowed us to draw conclusions about the present situation with antimicrobial susceptibility of N. gonorrhoeae in Russia and demonstrated the possibility of using hydrogel microarrays to control the spread of antibiotic resistance.

Modelling response strategies for controlling gonorrhoea outbreaks in men who have sex with men in Australia

The ability to treat gonorrhoea with current first-line drugs is threatened by the global spread of extensively drug resistant (XDR) Neisseria gonorrhoeae (NG) strains. In Australia, urban transmission is high among men who have sex with men (MSM) and importation of an XDR NG strain in this population could result in an epidemic that would be difficult and costly to control. An individual-based, anatomical site-specific mathematical model of NG transmission among Australian MSM was developed and used to evaluate the potential for elimination of an imported NG strain under a range of case-based and population-based test-and-treat strategies. When initiated upon detection of the imported strain, these strategies enhance the probability of elimination and reduce the outbreak size compared with current practice (current testing levels and no contact tracing). The most effective strategies combine testing targeted at regular and casual partners with increased rates of population testing. However, even with the most effective strategies, outbreaks can persist for up to 2 years post-detection. Our simulations suggest that local elimination of imported NG strains can be achieved with high probability using combined case-based and population-based test-and-treat strategies. These strategies may be an effective means of preserving current treatments in the event of wider XDR NG emergence.

In most high-income settings, gonorrhoea is endemic among men who have sex with men (MSM). While gonorrhoea remains readily treatable with antibiotics, there are major concerns about the threat of antimicrobial resistance arising from recent reports of treatment failure with first-line therapy and limited remaining treatment options. Here we investigated the potential for test-and-treat response strategies to eliminate such strains before their prevalence reaches a level requiring a shift to new first line therapies. Rather than directly consider resistance, we explore the mitigating effect of various test-and-treat measures on outbreaks of a generic imported strain which remains treatable. This is done within the framework of a realistic mathematical model of gonorrhoea spread in an MSM community that captures cases, anatomical sites of infection and sexual contacts at an individual level, calibrated to relevant Australian epidemiological data. The results indicate that strategies such as partner testing and treatment in combination with elevated asymptomatic community testing are highly effective in mitigating outbreaks but can take up to 2 years to achieve elimination. As there are currently no clear alternative drugs of proven efficacy and safety to replace ceftriaxone in first-line therapy, these promising results suggest potential for use of these outbreak response strategies to preserve current treatment recommendations.

Emergence and Characterization of a Ceftriaxone-Resistant Neisseria gonorrhoeae FC428 Clone Evolving Moderate-Level Resistance to Azithromycin in Shenzhen, China

We here described a ceftriaxone-resistant Neisseria gonorrhoeae FC428 clone (YL201) with moderate-level resistance to azithromycin in Shenzhen, South China in 2020. The NG-STAR type of YL201 is ST2238, containing a mosaic penA-60.001 allele, which is a typical characteristic of FC428 clone. YL201 harbours four copies of the 23S rRNA C2611T mutation, conferring moderate-level resistance to azithromycin. The MLST type is ST1600, identical with two N. gonorrhoeae FC428 clones identified in Hangzhou. Genome-wide phylogeny analysis demonstrates that YL201 is clustered with other FC428 clones from Hangzhou (South-east China) and Chengdu (South-west China). Isolates within this cluster have relatively higher MIC for ceftriaxone and display closely related MLST STs (ST1600 and ST7363) but are different from the ST of typical FC428 clone (ST1903). As ST1600 and ST7363 are common STs in Shenzhen, the further spread of FC428 clones may increase the severity of gonococcal resistance. In summary, identifying a multidrug-resistant (MDR) N. gonorrhoeae isolate in Shenzhen showed FC428 clones have undergone further transmission in China and presented more extensive and concerning antimicrobial resistance (AMR) characteristics during the spread.

Australian Gonococcal Surveillance Programme Annual Report, 2020

Abstract

The Australian Gonococcal Surveillance Programme (AGSP), established in 1981, has continuously monitored antimicrobial resistance in clinical isolates of Neisseria gonorrhoeae for more than 40 years. In 2020, a total of 7,222 clinical isolates of gonococci from patients in the public and private sectors, in all jurisdictions, were tested for in vitro antimicrobial susceptibility by standardised methods. Current treatment recommendations for gonorrhoea, for the majority of Australia, continues to be dual therapy with ceftriaxone and azithromycin. In 2020, decreased susceptibility (DS) to ceftriaxone (minimum inhibitory concentration [MIC] value ≥ 0.06 mg/L) was found nationally in 0.9% of isolates. There was one isolate, reported from Victoria in 2020, that was resistant to ceftriaxone (MIC value ≥ 0.25 mg/L). Resistance to azithromycin (MIC value ≥ 1.0 mg/L) was found nationally in 3.9% of N. gonorrhoeae isolates, continuing a downward trend observed and reported since 2017. Isolates with high-level resistance to azithromycin (MIC value ≥ 256 mg/L) are identified sporadically in Australia; in 2020, there was one such isolate reported in Queensland. In 2020, penicillin resistance was found in 27% of gonococcal isolates nationally, and ciprofloxacin resistance in 36%; however, there is considerable variation by jurisdiction. In some remote settings, penicillin resistance remains low, and this drug continues to be recommended as part of an empiric therapy strategy. In 2020, in remote Northern Territory, no penicillin resistance was reported, and in remote Western Australia 5/116 of gonococcal isolates (4.3%) were penicillin resistant. There was one ciprofloxacin-resistant isolate reported from remote Northern Territory, and ciprofloxacin resistance rates remain comparatively low in remote Western Australia (4/116; 3.4%).

Mutations in PBP2 from ceftriaxone-resistant Neisseria gonorrhoeae alter the dynamics of the β3-β4 loop to favor a low-affinity drug-binding state

Resistance to the extended-spectrum cephalosporin ceftriaxone in the pathogenic bacteria Neisseria gonorrhoeae is conferred by mutations in penicillin-binding protein 2 (PBP2), the lethal target of the antibiotic, but how these mutations exert their effect at the molecular level is unclear. Using solution NMR, X-ray crystallography, and isothermal titration calorimetry, we report that WT PBP2 exchanges dynamically between a low-affinity state with an extended β3–β4 loop conformation and a high-affinity state with an inward β3–β4 loop conformation. Histidine-514, which is located at the boundary of the β4 strand, plays an important role during the exchange between these two conformational states. We also find that mutations present in PBP2 from H041, a ceftriaxone-resistant strain of N. gonorrhoeae, increase resistance to ceftriaxone by destabilizing the inward β3–β4 loop conformation or stabilizing the extended β3–β4 loop conformation to favor the low-affinity drug-binding state. These observations reveal a unique mechanism for ceftriaxone resistance, whereby mutations in PBP2 lower the proportion of target molecules in the high-affinity drug-binding state and thus reduce inhibition at lower drug concentrations.

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.

Genomic Epidemiology of Azithromycin-Nonsusceptible Neisseria gonorrhoeae, Argentina, 2005-2019

Azithromycin-nonsusceptible Neisseria gonorrhoeae strains are an emerging global public health threat. During 2015–2018, the prevalence of azithromycin-nonsusceptible gonococcal infection increased significantly in Argentina. To investigate the genomic epidemiology and resistance mechanisms of these strains, we sequenced 96 nonsusceptible isolates collected in Argentina during 2005–2019. Phylogenomic analysis revealed 2 main clades, which were characterized by a limited geographic distribution, circulating during January 2015–November 2019. These clades included the internationally spreading multilocus sequence types (STs) 1580 and 9363. The ST1580 isolates, which had MICs of 2–4 μg/mL, had mutations in the 23S rRNA. The ST9363 isolates, which had MICs of 2–4 or >256 μg/mL, had mutations in the 23S rRNA, a mosaic mtr locus, or both. Identifying the geographic dissemination and characteristics of these predominant clones will guide public health policies to control the spread of azithromycin-nonsusceptible N. gonorrhoeae in Argentina.

Demographic and behavioural risk factors associated with reduced susceptibility of Neisseria gonorrhoeae to first-line antimicrobials in South African men with gonococcal urethral discharge

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

Genomic Analysis of the Predominant Strains and Antimicrobial Resistance Determinants Within 1479 Neisseria gonorrhoeae Isolates From the US Gonococcal Isolate Surveillance Project in 2018

BACKGROUND

The prevalence of Neisseria gonorrhoeae (GC) isolates with elevated minimum inhibitory concentrations to various antibiotics continues to rise in the United States and globally. Genomic analysis provides a powerful tool for surveillance of circulating strains, antimicrobial resistance determinants, and understanding of transmission through a population.

METHODS

Neisseria gonorrhoeae isolates collected from the US Gonococcal Isolate Surveillance Project in 2018 (n = 1479) were sequenced and characterized. Whole-genome sequencing was used to identify sequence types, antimicrobial resistance profiles, and phylogenetic relationships across demographic and geographic populations.

RESULTS

Genetic characterization identified that (1) 80% of the GC isolates were represented in 33 multilocus sequence types, (2) isolates clustered in 23 major phylogenetic clusters with select phenotypic and demographic prevalence, and (3) common antimicrobial resistance determinants associated with low-level or high-level decreased susceptibility or resistance to relevant antibiotics.

CONCLUSIONS

Characterization of this 2018 Gonococcal Isolate Surveillance Project genomic data set, which is the largest US whole-genome sequence data set to date, sets the basis for future prospective studies, and establishes a genomic baseline of GC populations for local and national monitoring.

Using a public database of Neisseria gonorrhoeae genomes to detect mutations associated with zoliflodacin resistance

BACKGROUND

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is an urgent global health threat. Zoliflodacin is a novel antibiotic undergoing clinical trials for the treatment of gonorrhoea. While there are limited data regarding zoliflodacin resistance in N. gonorrhoeae, three amino acid mutations have been associated with increased MICs of zoliflodacin.

OBJECTIVES

To determine the prevalence of three amino acid mutations associated with zoliflodacin resistance within a large, public database of nearly 13 000 N. gonorrhoeae genomes.

METHODS

PathogenWatch is an online genomic epidemiology platform with a public database of N. gonorrhoeae genomes. That database was used to extract gyrB sequence data and a Basic Local Alignment Search Tool (BLAST) search was performed to identify any of the three amino acid mutations in GyrB that are associated with increased zoliflodacin MICs: D429N, K450N or K450T. As a control for the search methodology, all GyrA sequences were also extracted and S91F mutations were identified and compared with the PathogenWatch database.

RESULTS

In total, 12 493 N. gonorrhoeae genomes from the PathogenWatch database were included. Among those genomes, none was identified that harboured any of the three mutations associated with increased zoliflodacin MICs. One genome was identified to have a mutation at position 429 in GyrB (D429V).

CONCLUSIONS

The findings suggest that the prevalence of the three mutations associated with zoliflodacin resistance in N. gonorrhoeae is very low. However, further research into the mechanisms of zoliflodacin resistance in N. gonorrhoeae is needed. Genomic epidemiology platforms like PathogenWatch can be used to enhance the global surveillance of AMR.

Vaccine Candidates for the Control and Prevention of the Sexually Transmitted Disease Gonorrhea

The World Health Organization (WHO) has placed N. gonorrhoeae on the global priority list of antimicrobial resistant pathogens and is urgently seeking the development of new intervention strategies. N. gonorrhoeae causes 86.9 million cases globally per annum. The effects of gonococcal disease are seen predominantly in women and children and especially in the Australian Indigenous community. While economic modelling suggests that this infection alone may directly cost the USA health care system USD 11.0–20.6 billion, indirect costs associated with adverse disease and pregnancy outcomes, disease prevention, and productivity loss, mean that the overall effect of the disease is far greater still. In this review, we summate the current progress towards the development of a gonorrhea vaccine and describe the clinical trials being undertaken in Australia to assess the efficacy of the current formulation of Bexsero^® in controlling disease.

Resistance-Guided Treatment of Gonorrhea: A Prospective Clinical Study

BACKGROUND

Novel treatment strategies to slow the continued emergence and spread of antimicrobial resistance in Neisseria gonorrhoeae are urgently needed. A molecular assay that predicts in vitro ciprofloxacin susceptibility is now available but has not been systematically studied in human infections.

METHODS

Using a genotypic polymerase chain reaction assay to determine the status of the N. gonorrhoeae gyrase subunit A serine 91 codon, we conducted a multisite prospective clinical study of the efficacy of a single oral dose of ciprofloxacin 500 mg in patients with culture-positive gonorrhea. Follow-up specimens for culture were collected to determine microbiological cure 5-10 days post-treatment.

RESULTS

Of the 106 subjects possessing culture-positive infections with wild-type gyrA serine N. gonorrhoeae genotype, the efficacy of single-dose oral ciprofloxacin treatment in the per-protocol population was 100% (95% 1-sided confidence interval, 97.5-100%).

CONCLUSIONS

Resistance-guided treatment of N. gonorrhoeae infections with single-dose oral ciprofloxacin was highly efficacious. The widespread introduction and scale-up of gyrA serine 91 genotyping in N. gonorrhoeae infections could have substantial medical and public health benefits in settings where the majority of gonococcal infections are ciprofloxacin susceptible.

CLINICAL TRIALS REGISTRATION

NCT02961751.