Epidemiology, Treatments, and Vaccine Development for Antimicrobial-Resistant Neisseria gonorrhoeae: Current Strategies and Future Directions

Characterization and antioxidant activity of nano-formulated berberine and cyperus rotundus extracts with anti-inflammatory effects in mastitis-induced rats

Bovine mastitis caused by infectious pathogens, mainly Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), constitutes a major destructive challenge for the dairy industry and public health. Berberine chloride (BER) and Cyperus rotundus possess a broad spectrum of anti-inflammatory, antioxidant, antibacterial, and antiproliferative activities; however, their bioavailability is low. This research aimed first to prepare an ethanolic extract of Cyperus rotundus rhizomes (CRE) followed by screening its phytochemical contents, then synthesis of BER and CRE loaded chitosan nanoparticles (NPs) (BER/CH-NPs and CRE/CH-NPs), afterward, the analysis of their loading efficiency in addition to the morphological and physicochemical characterization of the formulated NPs employing Scanning Electron Microscopy (SEM), Zeta Potential (ZP), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) assessments compared to their crude forms to evaluate the enhancement of bioavailability and stability. Isolation of bacterial strains from the milk of mastitic cows, used for induction of mammary gland (MG) inflammation in female albino rats, and a preliminary investigation of the prophylactic oral doses of the prepared NPs against S. aureus-induced mastitis in female rats. The minimal inhibitory concentration (MIC) of BER/CH-NPs and CRE/CH-NPs is 1 mg/kg b.w. BER/CH-NPs and CRE/CH-NPs alone or in combination show significant (P ≤ 0.05) DPPH radical scavenging activity (69.2, 88.5, and 98.2%, respectively) in vitro. Oral administration of BER/CH-NPs and CRE/CH-NPs to mastitis rats significantly (P ≤ 0.05) attenuated TNF-α (22.1, 28.6 pg/ml), IL-6 (33.4, 42.9 pg/ml), IL-18 (21.7, 34.7 pg/ml), IL-4 (432.9, 421.6 pg/ml), and MPO (87.1, 89.3 pg/ml) compared to mastitis group alongside the improvement of MG histopathological findings without any side effect on renal and hepatic functions. Despite promising results with BER and CRE nanoparticles, the study is limited by small-scale trials, a focus on acute administration, and partially explored nanoparticle-biological interactions, with no economic or scalability assessments. Future research should address these limitations by expanding trial scopes, exploring interactions further, extending study durations, and assessing economic and practical scalability. Field trials and regulatory compliance are also necessary to ensure practical application and safety in the dairy industry. In conclusion, the in vitro and in vivo results proved the antioxidant and anti-inflammatory efficacy of BER/CH-NPs and CRE/CH-NPs in low doses with minimal damage to the liver and kidney functions, supposing their promising uses in mastitis treatment.

Addressing Sexually Transmitted Infections Due to Neisseria gonorrhoeae in the Present and Future

It was in the 1800s when the first public publications about the infection and treatment of gonorrhoea were released. However, the first prevention programmes were only published a hundred years later. In the 1940s, the concept of vaccination was introduced into clinical prevention programmes to address early sulphonamide resistance. Since then, tons of publications on Neisseria gonorrhoeae are undisputed, around 30,000 publications today. Currently, the situation seems to be just as it was in the last century, nothing has changed or improved. So, what are we doing wrong? And more importantly, what might we do? The review presented here aims to review the current situation regarding the resistance mechanisms, prevention programmes, treatments, and vaccines, with the challenge of better understanding this special pathogen. The authors have reviewed the last five years of advancements, knowledge, and perspectives for addressing the Neisseria gonorrhoeae issue, focusing on new therapeutic alternatives.

Low Oxygen Concentration Reduces Neisseria gonorrhoeae Susceptibility to Resazurin

Neisseria gonorrhoeae has developed resistance to every antibiotic currently approved for the treatment of gonorrhea, prompting the development of new therapies. The phenoxazine dye resazurin exhibits robust antimicrobial activity against N. gonorrhoeae in vitro but fails to limit vaginal colonization by N. gonorrhoeae in a mouse model. The lack of in vivo efficacy may be due to oxygen limitation as in vitro susceptibility assays with resazurin are conducted under atmospheric oxygen while a microaerophilic environment is present in the vagina. Here, we utilized broth microdilution assays to determine the susceptibility of N. gonorrhoeae to resazurin under low and atmospheric oxygen conditions. The minimal inhibitory concentration of resazurin for multiple N. gonorrhoeae clinical isolates was significantly higher under low oxygen. This effect was specific to resazurin as N. gonorrhoeae was equally susceptible to other antibiotics under low and atmospheric oxygen conditions. The reduced susceptibility of N. gonorrhoeae to resazurin under low oxygen was largely attributed to reduced oxidative stress, as the addition of antioxidants under atmospheric oxygen mimicked the reduced susceptibility to resazurin observed under low oxygen. Together, these data suggest oxygen concentration is an important factor to consider when evaluating the efficacy of new antibiotics against N. gonorrhoeae in vitro.

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.

Evaluating the efficacy of different antibiotics against Neisseria gonorrhoeae: a pharmacokinetic/pharmacodynamic analysis using Monte Carlo simulation

BACKGROUND

With the widespread use of antibiotics, antimicrobial resistance in Neisseria gonorrhoeae is worsening. The objective of this study was to evaluate the efficacy changes of seven antibiotics in the treatment of N. gonorrhoeae by using Monte Carlo simulation combined with pharmacokinetics/pharmacodynamics/ (PK/PD).

METHODS

The minimum inhibitory concentration (MIC) of antibiotics against clinical isolates from 2013 to 2020 in Nanjing, China, was determined by agar dilution method. The probability of target attainment (PTA) was estimated at each MIC value and the cumulative fraction of response (CFR) was calculated to evaluate the efficacy of these regimens.

RESULTS

All dosage regimens of seven antibiotics achieved PTAs ≥ 90% for MIC ≤ 0.06 µg/ml. But when the MIC was increased to 1 µg/ml, PTAs at each MIC value exceeded 90% only for ceftriaxone 1,000 mg and 2,000 mg, zoliflodacin 2,000 mg and 3,000 mg. Among them, the CFR values of each dosing regimen against N. gonorrhoeae only for ceftriaxone, cefixime and zoliflodacin were ≥ 90% in Nanjing from 2013 to 2020.

CONCLUSIONS

Cephalosporins are still the first-line drugs in the treatment of gonorrhea. However, the elevated MIC values of cephalosporins can lead to decline in clinical efficacy of the conventional dose regimens, and increasing the dose of ceftriaxone to 1,000 mg-2,000 mg may improve the efficacy. In addition, zoliflodacin is possible to be a potential therapeutic agent in the future.

Characterization of exclusively non-commensal Neisseria gonorrhoeae pangenome to prioritize globally conserved and thermodynamically stable vaccine candidates using immune-molecular dynamic simulations

Neisseria gonorrhoeae (Ngo) has emerged as a global threat leading to one of the most common sexually transmitted diseases in the world. It has also become one of the leading antimicrobial resistant organisms, resulting in fewer treatment options and an increased morbidity. Therefore, in recent years, there has been an increased focus on the development of new treatments and preventive strategies to combat its infection. In this study, we have combined the most conserved epitopes from the completely assembled strains of Ngo to develop a universal and a thermodynamically stable vaccine candidate. For our vaccine design, the epitopes were selected for their high immunogenicity, non-allergenicity and non-cytotoxicity, making them the ideal candidates for vaccine development. For the screening process, several reverse vaccinology tools were employed to rigorously extract non-homologous and immunogenic epitopes from the selected proteins. Consequently, a total number of 3 B-cell epitopes and 6 T-cell epitopes were selected and joined by multiple immune-modulating adjuvants and linkers to generate a promiscuous immune response. Additionally, the stability and flexible nature of the vaccine construct was confirmed using various molecular dynamic simulation tools. Overall, the vaccine candidate showed promising binding affinity to various HLA alleles and TLR receptors; however, further studies are needed to assess its efficacy in-vivo. In this way, we have designed a multi-subunit vaccine candidate to potentially combat and control the spread of N. gonorrhoeae.

[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.

Analysis and prediction of the incidence and prevalence trends of gonorrhea in China

To understand the epidemiological trend of gonorrhea in China from 2004 to 2021, predict the prevalence of the disease, and provide basic theory and data support for monitoring and managing gonorrhea. Gonorrhea incidence data in China from 2004 to 2021 were collected through the China Public Health Science Data Center and National Administration of Disease Prevention and Control, and the incidence and epidemiological characteristics were analyzed. Statistical analysis was performed using Joinpoint and autoregressive integrated moving average (ARIMA) models. A linear correlation model was used to analyze the correlation between gross domestic product (GDP) and the incidence rate. From 2004 to 2021, a total of 2,289,435 cases of gonorrhea were reported in China, with an average reported incidence rate of 9.46/100,000 people and a downward followed by an upward trend. Individuals with gonorrhea were primarily 20-30 y of age, with 1,034,847 cases (53.38%) from 2004 to 2018. The trend of increasing incidence was most obvious in the 10-20 age group (5,811 cases in 2004 to 12,752 cases in 2018, AAPC = 6.1, P < .001). The incidence of gonorrhea in China was negatively correlated with GDP from 2004 to 2021 (r = -0.547, P = .019). The correlation coefficient between the average incidence growth rate of each region from 2012 to 2018 and the average growth rate of regional GDP was 0.673 (P < .01). The root mean square error (RMSE) of the ARIMA model was 4.89%, showing powerful performance. There would be 97,910 gonorrhea cases in 2023 as predicted by the model.

Chlamydial and Gonococcal Genital Infections: A Narrative Review

Sexually transmitted infections (STIs) constitute one of the leading causes of disease burden worldwide, leading to considerable morbidity, mortality, health expenditures, and stigma. Of note are the most common bacterial STIs, chlamydial and gonococcal infections, whose etiological agents are Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG), respectively. Despite being usually asymptomatic, in some cases these infections can be associated with long-term severe complications, such as pelvic inflammatory disease, chronic pelvic pain, infertility, ectopic pregnancy, and increased risk of other STIs acquisition. As the symptoms, when present, are usually similar in both infections, and in most of the cases these infections co-occur, the dual-test strategy, searching for both pathogens, should be preferred. In line with this, herein we focus on the main aspects of CT and NG infections, the clinical symptoms as well as the appropriate state-of-the-art diagnostic tests and treatment. Cost-effective strategies for controlling CT and NG infections worldwide are addressed. The treatment for both infections is based on antibiotics. However, the continuing global rise in the incidence of these infections, concomitantly with the increased risk of antibiotics resistance, leads to difficulties in their control, particularly in the case of NG infections. We also discuss the potential mechanism of tumorigenesis related to CT infections. The molecular bases of CT and NG infections are addressed, as they should provide clues for control or eradication, through the development of new drugs and/or effective vaccines against these pathogens.

An overview of novel antimicrobial carbonic anhydrase inhibitors

INTRODUCTION

Four different genetic families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) are present in bacteria, α-, β-, γ- and ι-CAs. They play relevant functions related to CO2, HCO3-/H+ ions homeostasis, being involved in metabolic biosynthetic pathways, pH regulation, and represent virulence and survival factors for bacteria in various niches. Bacterial CAs started to be considered druggable targets in the last decade, as their inhibition impairs survival, growth, and virulence of these pathogens.

AREAS COVERED

Significant advances were registered in the last years for designing effective inhibitors of sulfonamide type for Helicobacter pylori α-CA, Neisseria gonorrhoeae α-CA, vacomycin-resistant enterococci (VRE) α- and γ-CAs, for which the in vivo validation has also been achieved. MIC-s in the range of 0.25-4.0 µg/mL for wild type and drug resistant N. gonorrhoeae strains, and of 0.007-2.0 µg/mL for VRE were observed for some 1,3,4-thiadiazole-2-sulfonamides, and acetazolamide was effective in gut decolonization from VRE.

EXPERT OPINION

Targeting bacterial CAs from other pathogens, among which Vibrio cholerae, Mycobacterium tuberculosis, Brucella suis, Salmonella enterica serovar Typhimurium, Legionella pneumophila, Porphyromonas gingivalis, Clostridium perfringens, Streptococcus mutans, Burkholderia pseudomallei, Francisella tularensis, Escherichia coli, Mammaliicoccus (Staphylococcus) sciuri, Pseudomonas aeruginosa, may lead to novel antibacterials devoid of drug resistance problems.

Devices for the transport and microbiological detection of Neisseria gonorrhoeae in sexual health clinic samples: a prospective comparative study

BACKGROUND

Propagation and microbiological detection of N. gonorrhoeae can be challenging due to the fastidious nature of the bacterium outside the human host environment. Different sample transport options were evaluated in order to address this issue.

METHODS

Symptomatic and high-risk patients consented to take part. Standard practice in clinics involve using a guanine and cytosine selective (GC) plate for transport and incubation. Other devices were assessed in two different studies. MWE's Sigma VCM™-a transport device for use between clinic and laboratory-was used in one study (n = 166). In the other, (n = 102), Biomed's Intray™ plates were used, which can be used for both initial transport and incubation at the destination laboratory.

RESULTS

In the Sigma VCM™ study, positive results were obtained for 14% (Sigma VCM™), 21% (GC plates); the distribution of outcomes did not significantly differ between the two microbiological sampling methods (p-value 0.09, Chi-squared test). Concerning the InTray™ sub-study, N. gonorrhoeae was detected in 9% (InTray™), 13% (GC plating) of cases respectively, with again no significant difference between the microbiological sampling methods (p-value 0.25). Regression analysis identified a significant association between N. gonorrhoeae detection and male patients, absence of dysuria and previous gonorrhoea infection.

CONCLUSION

No significant difference in rate of microbiological detection of N. gonorrhoeae could be detected between different transport devices in a sexual health clinic setting. Performance appraisal of transport devices for bacterial sexually transmitted infection can inform practitioners' options regarding said devices.

Effect of food on the pharmacokinetics of zoliflodacin granules for oral suspension: Phase I open-label randomized cross-over study in healthy subjects

Gonorrhea is a sexually transmitted infection for which antibiotic treatment options have declined due to increasing antibiotic resistance. Zoliflodacin, an investigational oral spiropyrimidinetrione antibiotic with activity against Neisseria gonorrhoeae strains that are multidrug-resistant, including to third-generation cephalosporins, is in phase III development for uncomplicated gonorrhea. This phase I, parallel, open-label, randomized, crossover study in healthy adults evaluated the effect of food on the pharmacokinetics of single 3 or 4 g doses of zoliflodacin administered as granules for oral suspension in the fasted state or after consumption of a standardized high-fat meal. Forty-seven out of 48 randomized subjects completed the study. Oral administration of zoliflodacin with food delayed the absorption rate, compared with fasted state, with time to maximum concentration (T_max ) increasing from 3 to 6 h for the 3 g dose, and 2.5 to 4 h for the 4 g dose, but had no impact on the elimination of zoliflodacin. The maximum concentration (C_max ) and area under the plasma concentration-time curve from time 0 to 24 h (AUC_(0-24) ) significantly increased with food by 52% and 94% for the 3 g dose, and by 89% and 108% for the 4 g dose. Forty-two percent of participants reported a total of 34 treatment-emergent adverse events (TEAEs), which were all considered mild in severity. Headache was the most common TEAE (22/48 subjects, 45.8%) and the only TEAE reported in more than one subject. In conclusion, administration of single 3 and 4 g doses of zoliflodacin as granules for oral suspension, with a high-fat meal was well-tolerated and resulted in statistically significant increases in peak and overall systemic exposure to zoliflodacin.

Colonization efficiency of multidrug-resistant Neisseria gonorrhoeae in a female mouse model

The rapid occurrence of gonococcal resistance to all classes of antibiotics could lead to untreatable gonorrhea. Thus, development of novel anti-Neisseria gonorrhoeae drugs is urgently needed. Neisseria gonorrhoeae FA1090 is the most used in gonococcal infection mouse models because of its natural resistance to streptomycin. Streptomycin inhibits the urogenital commensal flora that permits gonococcal colonization. However, this strain is drug-susceptible and cannot be used to investigate the efficacy of novel agents against multidrug-resistant N. gonorrhoeae. Hence, to test the in vivo efficacy of new therapeutics against N. gonorrhoeae resistant to the frontline antibiotics, azithromycin, or ceftriaxone, we constructed streptomycin-resistant mutants of N. gonorrhoeae CDC-181 (azithromycin-resistant) and WHO-X (ceftriaxone-resistant). We identified the inoculum size needed to successfully colonize mice. Both mutants, CDC-181-rpsLA128G and WHO-X-rpsLA128G, colonized the genital tract of mice for 14 days with 100% colonization observed for at least 7 days. CDC-181-rpsLA128G demonstrated better colonization of the murine genital tract compared to WHO-X-rpsLA128G. Lower inoculum of WHO-X-rpsLA128G (105 and 106 CFU) colonized mice better than higher inoculum. Overall, our results indicate that CDC-181-rpsLA128G and WHO-X-rpsLA128G can colonize the lower genital tract of mice and are suitable to be used in mouse models to investigate the efficacy of antigonococcal agents.

Computer-aided genomic data analysis of drug-resistant Neisseria gonorrhoeae for the Identification of alternative therapeutic targets

Neisseria gonorrhoeae is an emerging multidrug resistance pathogen that causes sexually transmitted infections in men and women. The N. gonorrhoeae has demonstrated an emerging antimicrobial resistance against reported antibiotics, hence fetching the attention of researchers to address this problem. The present in-silico study aimed to find putative novel drug and vaccine targets against N. gonorrhoeae infection by the application of bioinformatics approaches. Core genes set of 69 N. gonorrhoeae strains was acquired from complete genome sequences. The essential and non-homologous metabolic pathway proteins of N. gonorrhoeae were identified. Moreover, different bioinformatics databases were used for the downstream analysis. The DrugBank database scanning identified 12 novel drug targets in the prioritized list. They were preferred as drug targets against this bacterium. A viable vaccine is unavailable so far against N. gonorrhoeae infection. In the current study, two outer-membrane proteins were prioritized as vaccine candidates via reverse vaccinology approach. The top lead B and T-cells overlapped epitopes were utilized to generate a chimeric vaccine construct combined with immune-modulating adjuvants, linkers, and PADRE sequences. The top ranked prioritized vaccine construct (V7) showed stable molecular interaction with human immune cell receptors as inferred during the molecular docking and MD simulation analyses. Considerable response for immune cells was interpreted by in-silico immune studies. Additional tentative validation is required to ensure the effectiveness of the prioritized vaccine construct against N. gonorrhoeae infection. The identified proteins can be used for further rational drug and vaccine designing to develop potential therapeutic entities against the multi-drug resistant N. gonorrhoeae.

Structural and Functional Annotation and Molecular Docking Analysis of a Hypothetical Protein from Neisseria gonorrhoeae: An In-Silico Approach

Background

Worldwide, Neisseria gonorrhoeae-related sexually transmitted infections (STIs) continue to be of significant public health concern. This obligate-human pathogen has developed a number of defenses against both innate and adaptive immune responses during infection, some of which are mediated by the pathogen's proteins. Hence, the uncharacterized proteins of N. gonorrhoeae can be annotated to get insight into the unique functions of this organism related to its pathogenicity and to find a more efficient therapeutic target.

Methods

In this study, a hypothetical protein (HP) of N. gonorrhoeae was chosen for analysis and an in-silico approach was used to explore various properties such as physicochemical characteristics, subcellular localization, secondary structure, 3D structures, and functional annotation of that HP. Finally, a molecular docking analysis was performed to design an epitope-based vaccine against that HP.

Results

This study has identified the potential role of the chosen HP of N. gonorrhoeae in plasmid transfer, cell cycle control, cell division, and chromosome partitioning. Acidic nature, thermal stability, cytoplasmic localization of the protein, and some of its other physicochemical properties have also been identified through this study. Molecular docking analysis has demonstrated that one of the T cell epitopes of the protein has a significant binding affinity with the human leukocyte antigen HLA-B∗15 : 01.

Conclusions

The in-silico characterization of this protein will help us understand molecular mechanism of action of N. gonorrhoeae and get an insight into novel therapeutic identification processes. This research will, therefore, enhance our knowledge to find new medications to tackle this potential threat to humankind.

Reliability of Genetic Alterations in Predicting Ceftriaxone Resistance in Neisseria gonorrhoeae Globally

Antimicrobial resistance in N. gonorrhoeae is increasing globally, and ceftriaxone is the recommended treatment for empirical therapy in most settings. Developing molecular assays to detect decreased ceftriaxone susceptibility is critical. Using PathogenWatch, a public database of N. gonorrhoeae genomes, antibiotic susceptibility data and DNA sequences of different genes associated with ceftriaxone resistance were extracted. That information was used to determine the sensitivity and specificity of different molecular markers and algorithms to predict decreased susceptibility to ceftriaxone. A total of 12,943 N. gonorrhoeae genomes were extracted from the PathogenWatch database, of which 9,540 genomes were used in the analysis. The sensitivity and specificity of specific molecular markers and algorithms were largely consistent with prior reports. Small variation (<10%) in either sensitivity or specificity occurred. Certain algorithms using different molecular markers at various prevalence of decreased ceftriaxone susceptibility identified a potentially clinically useful range of positive and negative predictive values. We validated previously described mutations and algorithms in a large public database containing a global collection of N. gonorrhoeae genomes. Certain mutations and algorithms resulted in sensitivity and specificity values consistent with those of prior studies. Further research is needed to integrate these markers and algorithms into the development of molecular assays to predict decreased ceftriaxone susceptibility. IMPORTANCE Antimicrobial resistance in Neisseria gonorrhoeae (N. gonorrhoeae), the causative agent of gonorrhea, is rising globally. Ceftriaxone is the last remaining antibiotic for empirical treatment of gonorrhea. Developing molecular tests to predict ceftriaxone resistance can help to improve detection and surveillance of ceftriaxone resistance. Here, we utilized PathogenWatch, a public global online database of N. gonorrhoeae genomes, to evaluate different genetic markers in predicting decreased susceptibility to ceftriaxone. We compiled MICs for ceftriaxone from the PathogenWatch database and used a computational approach to extract all the genetic markers from the genomic data. We determined the sensitivity and specificity for predicting decreased ceftriaxone susceptibility among several combinations of genetic markers. We identified several combinations of genetic markers with high predictive values for decreased susceptibility to ceftriaxone. These combinations of genetic markers might be promising candidates for future molecular tests to predict ceftriaxone resistance.

Neisseria mucosa Does Not Inhibit the Growth of Neisseria gonorrhoeae

Antibiotic-sparing treatments are required to prevent the further emergence of antimicrobial resistance in Neisseria gonorrhoeae. Commensal Neisseria species have previously been found to inhibit the growth of pathogenic Neisseria species. For example, a previous study found that three out of five historical isolates of Neisseria mucosa could inhibit the growth of N. gonorrhoeae. In this study, we used agar overlay assays to assess if 24 circulating and historical isolates of Neisseria mucosa could inhibit the growth of 28 circulating and historical isolates of N. gonorrhoeae. Although pitting around each colony of N. mucosa created an optical illusion of decreased growth of N. gonorrhoeae, we found no evidence of inhibition (n = 24). In contrast, positive controls of Streptococcus pneumoniae and Escherichia coli demonstrated a strong inhibitory effect against the growth of N. gonorrhoeae.

Dissemination and genome analysis of high-level ceftriaxone-resistant penA 60.001 Neisseria gonorrhoeae strains from the Guangdong Gonococcal Antibiotics Susceptibility Programme (GD-GASP), 2016-2019

Background: After Neisseria gonorrhoeae FC428 was first found in Japan, ceftriaxone-resistant strains disseminated globally, and the gonococcal resistance rate increased remarkably. Epidemiological investigations are greatly significant for the analysis of antimicrobial resistance (AMR) trends, molecular features and evolution. Objectives: To clarify the AMR trend from 2016–2019 and reveal the molecular characteristics and evolution of ceftriaxone-resistant penA 60.001 isolates. Methods: The minimum inhibitory concentrations (MICs) of antibiotics against 4113 isolates were detected by the agar dilution method. N. gonorrhoeae multiantigen sequence typing (NG-MAST), multilocus sequence typing (MLST) and N.gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) were used to identify the sequence types. Genome analysis was conducted to analyze resistance genes, virulence factors, and evolutionary sources. Results: Isolates with decreased ceftriaxone susceptibility have increased from 2.05% (2016) to 16.18% (2019). Six ceftriaxone-resistant isolates possessing penA 60.001 appeared in Guangdong Province, and were resistant to ceftriaxone, penicillin, tetracycline, ciprofloxacin and cefixime, but susceptible to azithromycin and spectinomycin. Single-nucleotide polymorphisms (SNPs) in the porB gene were the major cause of different NG-MAST types. ST1903 was the main NG-STAR genotype and only strain-ZH545 was ST7365, with molecular features consistent with the MICs. Furthermore, different MLSTs suggested diverse evolutionary sources. Genome analysis revealed a set of virulence factors along with the resistance genes “penA” and “blaTEM-1B”. Half of penA 60.001 strains were fully mixed with global FC428-related strains. Conclusions: Global FC428-related clones have disseminated across Guangdong, possibly causing decreased ceftriaxone susceptibility. Enhanced gonococcal surveillance will help elucidate the trajectory of transmission and curb further dissemination.

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.

The role of vaccines in combating antimicrobial resistance (AMR) bacteria

Most pathogens have developed an intrinsic capacity to thrive by developing resistance to antimicrobial compounds utilized in treatment. Antimicrobial resistance arises when microbial agents such as bacteria, viruses, fungi, and parasites alter their behaviour to make current conventional medicines inefficient. Vaccination is one of the most effective strategies to fight antimicrobial resistance. Vaccines, unlike drugs, are less likely to produce resistance since they are precise to their target illnesses. Vaccines against infectious agents such as Streptococcus pneumoniae and Haemophilus influenzae have already been shown to reduce tolerance to antimicrobial medications; however, vaccines against some antimicrobial-resistant pathogens such as Vibrio cholerae, Salmonella typhi, Escherichia coli, nosocomial infections, and pulmonary and diarrheal disease viruses require more research and development. This paper describes vaccine roles in combatting antimicrobial resistance, quantifies the overall advantages of vaccination as an anti-antimicrobial resistance approach, analyzes existing antimicrobial vaccines and those currently under development, and emphasizes some of the obstacles and prospects of vaccine research and development.

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.