Molecular epidemiology of Neisseria gonorrhoeae isolates from Saskatchewan, Canada: utility of NG-MAST in predicting antimicrobial susceptibility regionally

Ameliorating Gonorrhea: Recent Therapeutic Adaptations and Scope to Improve its Prevailing Condition

BACKGROUND

Gonorrhea is a sexually transmitted infection (STI) caused by the bacteria Neisseria gonorrhoeae. According to recent research, the prevalence of gonorrhea has been increasing in many parts of the world, with some areas reporting high rates of antibiotic resistance. In the United States, the Centers for Disease Control and Prevention (CDC) reported that the number of reported gonorrhea cases increased by 56% between 2015 and 2019. Globally, the World Health Organization (WHO) estimated that there were 87 million new cases of gonorrhea in 2016, with the highest burden of infection in low- and middle-income countries. Research has also shown that gonorrhea is becoming increasingly resistant to conventional antibiotics, increasing the prevalence of gonorrhea. This raises concerns and challenges in disease management.

OBJECTIVES

The present review gives updated insight on the current state of the disease, challenges, and shortcomings of existing approaches along with the modern and alternative direction like vaccine development, its challenges, and scope to confront the existing state of drug resistance and increased rate of incidence. Alternative strategies like immunotherapy and phage therapy along with recent antibiotics researched for the treatment of gonorrhea.

CONCLUSION

The review provides a thorough insight into the current state of the disease and various available methods used currently and recommended by WHO. To overcome disease prevalence, various alternate therapies are coming into the limelight. However, scientists and researchers show a lack of interest in the drug development and research of gonorrhea, due to less commercial scope, lack of funding, and limited scope in the scientific scenario. These hurdles need to be overcome to meet the WHO vision of reducing gonorrhea by 90% by 2030. So, there is a need to optimize the drug therapy (optimizing dosing schedule, and precision monitoring) to reduce the chance of drug resistance. Also, there is a wide scope for drug and therapeutic system development.

In Vitro Activity of Ertapenem against Neisseria gonorrhoeae Clinical Isolates with Decreased Susceptibility or Resistance to Extended-Spectrum Cephalosporins in Nanjing, China (2013 to 2019)

Neisseria gonorrhoeae isolates collected in Nanjing, China, that possessed decreased susceptibility (or resistance) to extended-spectrum cephalosporins (ESCs) were examined for susceptibility to ertapenem, and their sequence types were determined. Ceftriaxone and cefixime MICs of ≥0.125 mg/L and ≥0.25 mg/L, respectively, were first determined in 259 strains isolated between 2013 and 2019, and then MICs of ertapenem were measured using the antimicrobial gradient Epsilometer test (Etest). Also, genetic determinants of ESC resistance were identified and N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed to analyze associations with ertapenem susceptibility. All isolates displayed ertapenem MICs between 0.006 mg/L and 0.38 mg/L; the overall MIC₅₀ and MIC₉₀ were 0.032 mg/L and 0.125 mg/L, respectively. Forty-four (17.0%) isolates displayed ertapenem MICs of ≥0.125 mg/L; 10 (3.9%) had MICs of ≥0.25 mg/L. The proportion of isolates with ertapenem MICs of ≥0.125 mg/L increased from 4.0% in 2013 to 20.0% in 2019 (χ² = 24.144, P < 0.001; chi-square test for linear trend). The penA mosaic allele was present in a significantly higher proportion of isolates with ertapenem MICs of ≥0.125 mg/L than of isolates with MICs of ≤0.094 mg/L) (97.7% versus 34.9%, respectively; χ² = 58.158, P < 0.001). ST5308 was the most prevalent NG-MAST type (8.5%); ST5308 was also significantly more common among isolates with ertapenem MICs of ≥0.125 mg/L than isolates with MICs of ≤0.094 mg/L (22.7% and 5.6%, respectively; χ² = 13.815, P = 0.001). Ertapenem may be effective therapy for gonococcal isolates with decreased susceptibility or resistance to ESCs and isolates with identifiable genetic resistance determinants.

Association of Neisseria gonorrhoeae genogroups and specific PBP2/MtrR/PorB mutation patterns with susceptibility to penicillin in a susceptible gonococcal population

Objectives

To ascertain whether the antimicrobial susceptibility of Neisseria gonorrhoeae isolates with differing susceptibilities to penicillin is associated with genogroups (GGs) and combined mutation patterns in PBP2 (penA), the multiple transfer resistance repressor (MtrR; mtrR) and porin B (PorB; porB).

Methods

The susceptibility of 146 clinical N. gonorrhoeae isolates to penicillin was determined using the agar dilution method and the interpretation criteria of CLSI. The DNA sequences of penA, mtrR and porB in isolates were compared with WT sequences and mutation patterns were determined. Isolates were typed by N. gonorrhoeae multi-antigen sequence typing (NG-MAST) and STs were grouped into specific GGs.

Results

The isolates tested carried 9 mutation patterns in PBP2 and 12 mutation patterns in each of MtrR and PorB. Of the 146 isolates, 121 (82.9%) were grouped into 13 different GGs. Isolates with penicillin MICs of 0.03-0.06 mg/L were significantly associated with GG25 (P < 0.05) and PBP2/MtrR/PorB mutation pattern I/WT/WT (P < 0.01). Isolates with a penicillin MIC of 1.0 mg/L were associated (P < 0.05) with: (i) GG3655 and mutation pattern XXII/A-;G45D/G120K;A121N; (ii) GG921 and mutation pattern IX/G45D/G120D;A121N; and (iii) GG1109 and mutation pattern IX/G45D/WT. Sixty percent (9/15) of penicillin-resistant isolates (MIC ≥2 mg/L) were GG3654 (P < 0.0001) and carried mutation pattern IX/G45D/G120K;A121D or IX/G45D/G120D;A121D (P < 0.05).

Conclusions

Specific mutation patterns in PBP2/MtrR/PorB were associated with specific GGs and penicillin susceptibility. This approach of typing strains and resistance patterns is ideal for predicting antimicrobial resistance and should be used in instances in which gonococcal culture is not available but DNA can be obtained from clinical specimens.

Can Social Network Analysis Help Address the High Rates of Bacterial Sexually Transmitted Infections in Saskatchewan?

BACKGROUND

Saskatchewan has one of the highest rates of gonorrhea among the Canadian provinces-more than double the national rate. In light of these high rates, and the growing threat of untreatable infections, improved understanding of gonorrhea transmission dynamics in the province and evaluation of the current system and tools for disease control are important.

METHODS

We extracted data from a cross-sectional sample of laboratory-confirmed gonorrhea cases between 2003 and 2012 from the notifiable disease files of the Regina Qu'Appelle Health Region. The database was stratified by calendar year, and social network analysis combined with statistical modeling was used to identify associations between measures of connection within the network and the odds of repeat gonorrhea and risk of coinfection with chlamydia at the time of diagnosis.

RESULTS

Networks were highly fragmented. Younger age and component size were positively associated with being coinfected with chlamydia. Being coinfected, reporting sex trade involvement, and component size were all positively associated with repeat infection.

CONCLUSIONS

This is the first study to apply social network analysis to gonorrhea transmission in Saskatchewan and contributes important information about the relationship of network connections to gonorrhea/chlamydia coinfection and repeat gonorrhea. This study also suggests several areas for change of systems-related factors that could greatly increase understanding of social networks and enhance the potential for bacterial sexually transmitted infection control in Saskatchewan.

Antimicrobial Resistance and Neisseria gonorrhoeae Multiantigen Sequence Typing Profile of Neisseria gonorrhoeae in New Delhi, India

Molecular epidemiology of 100 consecutive gonococcal isolates collected between April 2010 and October 2013 from New Delhi was investigated using Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) along with its association with antimicrobial resistance profiles. Neisseria gonorrhoeae isolates were assigned into 60 different sequence types and 43 (71.6%) were novel. Sole representation was seen in 76.6% sequence types. There was significant association between ST6058 and resistance to penicillin (P = 0.00) and tetracycline (P = 0.002).

Genomic sequencing of Neisseria gonorrhoeae to respond to the urgent threat of antimicrobial-resistant gonorrhea

The development of resistance of Neisseria gonorrhoeae to available first-line antibiotics, including penicillins, tetracyclines, fluoroquinolones and cephalosporins, has led to the circulation of multidrug-resistant gonorrhea at a global scale. Advancements in high-throughput whole-genome sequencing (WGS) provide useful tools that can be used to enhance gonococcal detection, treatment and management capabilities, which will ultimately aid in the control of antimicrobial resistant gonorrhea worldwide. In this minireview, we discuss the application of WGS of N. gonorrhoeae to strain typing, phylogenomic, molecular surveillance and transmission studies. We also examine the application of WGS analyses to the public health sector as well as the potential usage of WGS-based transcriptomic and epigenetic methods to identify novel gonococcal resistance mechanisms.

Neisseria gonorrhoeae Sequence Typing for Antimicrobial Resistance, a Novel Antimicrobial Resistance Multilocus Typing Scheme for Tracking Global Dissemination of N. gonorrhoeae Strains

A curated Web-based user-friendly sequence typing tool based on antimicrobial resistance determinants in Neisseria gonorrhoeae was developed and is publicly accessible (https://ngstar.canada.ca). The N. gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR) molecular typing scheme uses the DNA sequences of 7 genes (penA, mtrR, porB, ponA, gyrA, parC, and 23S rRNA) associated with resistance to β-lactam antimicrobials, macrolides, or fluoroquinolones. NG-STAR uses the entire penA sequence, combining the historical nomenclature for penA types I to XXXVIII with novel nucleotide sequence designations; the full mtrR sequence and a portion of its promoter region; portions of ponA, porB, gyrA, and parC; and 23S rRNA sequences. NG-STAR grouped 768 isolates into 139 sequence types (STs) (n = 660) consisting of 29 clonal complexes (CCs) having a maximum of a single-locus variation, and 76 NG-STAR STs (n = 109) were identified as unrelated singletons. NG-STAR had a high Simpson's diversity index value of 96.5% (95% confidence interval [CI] = 0.959 to 0.969). The most common STs were NG-STAR ST-90 (n = 100; 13.0%), ST-42 and ST-91 (n = 45; 5.9%), ST-64 (n = 44; 5.72%), and ST-139 (n = 42; 5.5%). Decreased susceptibility to azithromycin was associated with NG-STAR ST-58, ST-61, ST-64, ST-79, ST-91, and ST-139 (n = 156; 92.3%); decreased susceptibility to cephalosporins was associated with NG-STAR ST-90, ST-91, and ST-97 (n = 162; 94.2%); and ciprofloxacin resistance was associated with NG-STAR ST-26, ST-90, ST-91, ST-97, ST-150, and ST-158 (n = 196; 98.0%). All isolates of NG-STAR ST-42, ST-43, ST-63, ST-81, and ST-160 (n = 106) were susceptible to all four antimicrobials. The standardization of nomenclature associated with antimicrobial resistance determinants through an internationally available database will facilitate the monitoring of the global dissemination of antimicrobial-resistant N. gonorrhoeae strains.

Rapid spread of Neisseria gonorrhoeae ciprofloxacin resistance due to a newly introduced resistant strain in Nuuk, Greenland, 2012-2015: a community-based prospective cohort study

OBJECTIVES

To determine the antimicrobial susceptibility and genotype distribution of Neisseria gonorrhoeae strains isolated from a cohort of patients in Nuuk, Greenland in order to assess the risk of rapid spread in the event of introduction of new strains.

METHODS

Gonococcal isolates (n=102) obtained from a prospective cohort study of ciprofloxacin resistance were collected between March 2012 and February 2013. Etest minimal inhibitory concentrations (MICs) were determined for ciprofloxacin, azithromycin, ceftriaxone, penicillin, tetracycline, spectinomycin and gentamicin. All isolates were subjected to molecular typing using N. gonorrhoeae multiantigen sequence typing (NG-MAST). After the introduction of a ciprofloxacin-resistant strain in early 2014, an additional 18 isolates were characterised.

RESULTS

During the study period, all 102 isolates were fully susceptible to ciprofloxacin (≤0.03 mg/L), azithromycin, spectinomycin, gentamicin and ceftriaxone. 10 different NG-MAST types circulated in Nuuk but 7 were found as single isolates, and 3 of the 7 belonged to 1 of the 3 major genogroups (G210, G9816 and G9817) together comprising 96% of the 102 isolates. ST210 accounted for 55% of the 102 strains. The newly introduced ciprofloxacin resistant strain belonged to ST2400 and dominated the population with 59% resistant strains within 6 months after its introduction. All G2400 strains had MICs≥2 mg/L.

CONCLUSIONS

Introduction of a ciprofloxacin-resistant strain into a very homogeneous N. gonorrhoeae population led to an explosive spread of the resistant clone, probably as a result of large sexual networks suggested by the strain homogeneity. Careful surveillance of antimicrobial susceptibility is essential to avoid widespread treatment failure in closed populations.

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification and clustering of Neisseria gonorrhoeae

Background

The sexually transmitted infection gonorrhea remains a public health concern for becoming resistant to drug treatments available. The purpose of this study was to evaluate the usefulness of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify and cluster Neisseria gonorrhoeae.

From a current monitoring in Italy, as part of the European Gonococcal Antimicrobial Surveillance Programme (EURO-GASP), 93 gonococci collected from 2007 to 2012 susceptible (44 isolates) and resistant (49 isolates) to cefixime were selected. Minimum Inhibitory Concentration (MIC) values for cefixime was assessed by Etest carried out in agreement with the manufacturer’s instructions and interpreted referring to European Committee on Antimicrobial Susceptibility testing (EUCAST) clinical breakpoints criteria. Data obtained by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and the dendrogram based on the concatenation of porB and tbpB genes were evaluated. MALDI-TOF MS, to reconfirm gonorrhea identification, analyzed single colonies from freshly grown isolates and applied directly on a ground-steel MALDI target plate. For the MALDI-TOF dendrogram cluster analysis, MSPs (Main Spectrum Profile) from each isolate were created acquiring 5000 shots from 10 technical replicates obtained from bacteria extraction.

Results

Molecular typing by NG-MAST showed 28 sequence types (STs); G1407 was the predominant accounting for 75 gonococci. All the 93 gonococci, except one, were correctly identified at species level by MALDI-TOF MS and G1407 isolates were divided into two clusters.

Conclusion

MALDI-TOF MS for a real-time detection and cluster analysis of gonorrhea is a promising tool for surveillance purposes. Moreover, additional studies are required to collect more data on the performance of MALDI-TOF MS for gonococci.

Molecular epidemiology of Neisseria gonorrhoeae using multi-antigen sequence typing and pulse-field gel electrophoresis in highly endemic Western Australian populations

Background

The remote and indigenous populations of Western Australia (WA) have one of the highest notification rates of gonorrhoea in the world. Despite this, the low rate of antimicrobial resistance in Neisseria gonorrhoeae from these regions permits the use of amoxycillin as empirical therapy. We describe the first molecular epidemiological study of gonococci isolated from this population using two different typing platforms.

Methods

Pulse-field gel electrophoresis (PFGE), Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST) and antimicrobial susceptibility tests were performed on 128 consecutive N. gonorrhoeae isolates cultured between January 2011 and December 2013. To highlight clusters isolates were evaluated based on their tbpB sequence types.

Results

No predominant NG-MAST or PFGE types were found. A total of 67 distinct PFGE pulsotypes were identified amongst the 128 isolates in this study with 20 PFGE pulsotypes representing 78 isolates. A total of 59 NG-MAST sequence types were found, represented by 45 porB alleles and 28 tbpB alleles with 13 tbpB genomogroups from 45 NG-MAST sequence types. TbpB genomogroup 29, represented by 45 isolates, was by far the most common genomogroup overall.

Conclusions

Results from this study suggest that gonococcal epidemiology in WA is quite different between remote regions and major population centres and, in some cases, geographically restricted. It is likely that isolates originating from endemic regions of WA mostly represent independent, small sexual networks with an infrequent interchange between other communities and regions. Given the high rate of antimicrobial resistance elsewhere in Australia, ongoing surveillance is essential to ensure the enduring efficacy of amoxycillin empiric use in the remote regions of WA.

Population structure of Neisseria gonorrhoeae based on whole genome data and its relationship with antibiotic resistance

Neisseria gonorrhoeae is the causative agent of gonorrhea, a sexually transmitted infection (STI) of major importance. As a result of antibiotic resistance, there are now limited options for treating patients. We collected draft genome sequence data and associated metadata data on 76 N. gonorrhoeae strains from around the globe and searched for known determinants of antibiotics resistance within the strains. The population structure and evolutionary forces within the pathogen population were analyzed. Our results indicated a cosmopolitan gonoccocal population mainly made up of five subgroups. The estimated ratio of recombination to mutation (r/m = 2.2) from our data set indicates an appreciable level of recombination occurring in the population. Strains with resistance phenotypes to more recent antibiotics (azithromycin and cefixime) were mostly found in two of the five population subgroups.

Demographic and behavioural characteristics predict bacterial STI reinfection and coinfection among a cross-sectional sample of laboratory-confirmed gonorrhea cases in a local health region from Saskatchewan, Canada

OBJECTIVES

We aimed to identify demographic and behavioural determinants associated with risk of repeat STI infection and coinfection with gonorrhea and chlamydia in the Regina Qu'Appelle Health Region, Saskatchewan.

METHODS

We extracted data from a cross-sectional sample of laboratory confirmed gonorrhea cases between 2003 and 2012 from the notifiable disease files of the Regina Qu'Appelle Health Region. Risk factors for repeater status were examined using logistic regression and for coinfection with gonorrhea and chlamydia using mixed-effects logistic regression to account for multiple diagnoses for individual clients.

RESULTS

Data from 1,143 cases (representing 1,027 unique individuals) and 1,524 reported contacts (representing 1,383 unique individuals) were extracted from the 10-year period. Factors associated with repeat infection entries in the database included younger age at first visit (p = 0.01), coinfection (p = 0.01), and sex trade involvement (p &lt; 0.01). Factors associated with coinfection at the time of diagnosis included younger age at diagnosis (p &lt; 0.001) and reported alcohol or drug abuse (p = 0.04).

CONCLUSION

In one of the first epidemiologic studies on gonorrhea in Saskatchewan, we have identified age, engagement in the sex trade, and drug and alcohol abuse as potential markers to identify clients with a high risk of reinfection and coinfection in the Regina Qu'Appelle Health Region. This information can help health care professionals in Saskatchewan's urban centres personalize their approach to counselling and treatment to optimize patient outcomes and disease control efforts, including potentially using expedited partner therapy and/or dual therapy where indicated.

Demographic and behavioural characteristics predict bacterial STI reinfection and coinfection among a cross-sectional sample of laboratory-confirmed gonorrhea cases in a local health region from Saskatchewan, Canada

OBJECTIVES

We aimed to identify demographic and behavioural determinants associated with risk of repeat STI infection and coinfection with gonorrhea and chlamydia in the Regina Qu'Appelle Health Region, Saskatchewan.

METHODS

We extracted data from a cross-sectional sample of laboratory confirmed gonorrhea cases between 2003 and 2012 from the notifiable disease files of the Regina Qu'Appelle Health Region. Risk factors for repeater status were examined using logistic regression and for coinfection with gonorrhea and chlamydia using mixed-effects logistic regression to account for multiple diagnoses for individual clients.

RESULTS

Data from 1,143 cases (representing 1,027 unique individuals) and 1,524 reported contacts (representing 1,383 unique individuals) were extracted from the 10-year period. Factors associated with repeat infection entries in the database included younger age at first visit (p = 0.01), coinfection (p = 0.01), and sex trade involvement (p &lt; 0.01). Factors associated with coinfection at the time of diagnosis included younger age at diagnosis (p &lt; 0.001) and reported alcohol or drug abuse (p = 0.04).

CONCLUSION

In one of the first epidemiologic studies on gonorrhea in Saskatchewan, we have identified age, engagement in the sex trade, and drug and alcohol abuse as potential markers to identify clients with a high risk of reinfection and coinfection in the Regina Qu'Appelle Health Region. This information can help health care professionals in Saskatchewan's urban centres personalize their approach to counselling and treatment to optimize patient outcomes and disease control efforts, including potentially using expedited partner therapy and/or dual therapy where indicated.