Estimating the prevalence of mixed-type gonococcal infections in Queensland, Australia

Culture-Independent Genotyping Improves Surveillance of Neisseria gonorrhoeae, Especially in Oropharyngeal Samples, the Netherlands, 2017 to 2018

It is important i to monitor the transmission and antimicrobial resistance of Neisseria gonorrhoeae (NG). Current surveillance relies on culturing, which frequently fails. Previously, a culture-independent genotyping method was developed based on NG multi-antigen sequence typing (NG-MAST). To determine whether crucial sequence types (STs) are missed during culture-dependent surveillance, NG-positive NAAT samples were genotyped, and the results of the culture-positive and culture-negative samples were compared. In total, 196 NG-positive NAAT samples, from January 2017 until August 2018, which were also routinely cultured, were retrospectively included. Genotyping was successful in 152 NAAT samples (77.0%), 33 NAAT samples failed, and 11 NAAT samples showed possible mixed strain infections. Oropharyngeal samples (n = 16) showed the largest increase in typing rate from 6.3% (1/16) success in culture-dependent genotyping to 81.3% (13/16) in culture-independent genotyping. Nine genogroups (n ≥ 5 samples) were found; all included both culture-positive and culture-negative NG. However, culture-independent surveillance revealed 14 additional STs in the culture-negative samples. Overall, culture-dependent surveillance could detect all genogroups, indicating that major trends could be identified with culture-dependent surveillance. However, culture-independent surveillance provides more STs, mixed infections and more oropharyngeal samples, giving a more detailed view and could result in an earlier detection of outbreaks and transmission.

Strategies for successful designing of immunocontraceptive vaccines and recent updates in vaccine development against sexually transmitted infections - A Review

Background

Objective

Methods

Results

Conclusion

Evidence of Recent Genomic Evolution in Gonococcal Strains With Decreased Susceptibility to Cephalosporins or Azithromycin in the United States, 2014-2016

BACKGROUND

Given the lack of new antimicrobials or a vaccine, understanding the evolutionary dynamics of Neisseria gonorrhoeae is a significant public and global health priority. We investigated the emergence and spread of gonococcal strains with decreased susceptibility to cephalosporins and azithromycin using detailed genomic analyses of gonococcal isolates collected in the United States, 2014-2016.

METHODS

We sequenced genomes of 649 isolates collected through the Gonococcal Isolate Surveillance Project. We examined the genetic relatedness of isolates and assessed associations between clades and various genotypic and phenotypic combinations.

RESULTS

We identified a large and clonal lineage of strains (MLST ST9363) associated with elevated azithromycin minimum inhibitory concentration (AZIem), characterized by a mosaic mtr locus (C substitution in the mtrR promoter, mosaic mtrR and mtrD). Mutations in 23S rRNA were sporadically distributed among AZIem strains. Another clonal group (MLST ST1901) possessed 7 unique PBP2 patterns, and it shared common mutations in other genes associated with cephalosporin resistance.

CONCLUSIONS

Whole-genome sequencing methods can enhance monitoring of antimicrobial resistant gonococcal strains by identifying gonococcal populations containing mutations of concern. These methods could inform the development of point-of-care diagnostic tests designed to determine the specific antibiotic susceptibility profile of a gonococcal infection in a patient.

Systematic review and survey of Neisseria gonorrhoeae ceftriaxone and azithromycin susceptibility data in the Asia Pacific, 2011 to 2016

BACKGROUND

Antimicrobial resistance in Neisseria gonorrhoeae is a global concern, with the ongoing emergence of ceftriaxone and azithromycin resistance threatening current treatment paradigms. To monitor the emergence of antimicrobial resistance in N. gonorrhoeae, the World Health Organization (WHO) Gonococcal Antimicrobial Surveillance Programme (GASP) has operated in the Western Pacific and South East Asian regions since 1992. The true burden of antimicrobial resistance remains unknown. In response, the objective of this study was to survey ceftriaxone and azithromycin susceptibility in N. gonorrhoeae across the western Pacific and south-east Asia, and interlink this data with systematically reviewed reports of ceftriaxone and azithromycin resistance.

METHODS AND FINDINGS

The WHO Collaborating Centre for Sexually Transmitted Infections and Antimicrobial Resistance, Sydney, coordinated annual surveys of gonococcal susceptibilities with participating laboratories, and additionally undertook a systematic review of reports detailing gonococcal ceftriaxone and azithromycin susceptibility data for locations geographically in the Asia Pacific from 2011 to 2016. It was found that surveillance of gonococcal antimicrobial resistance remains limited in the Asia Pacific, with weaker surveillance of azithromycin versus ceftriaxone. Ninety-three published reports were identified (including national reports) which documented susceptibility data for ceftriaxone and azithromycin. GASP survey data was available for 21 countries, territories or areas, and suggested MICs are increasing for ceftriaxone and azithromycin. Between 2011 and 2016, the percentage of locations reporting >5% of gonococcal isolates with MICs to ceftriaxone meeting WHO's definition of decreased susceptibility (MIC ≥ 0.125 mg/L) increased from 14.3% to 35.3% and the percentage of locations reporting >5% of gonococcal isolates with azithromycin resistance (MIC ≥ 1 mg/L) increased from 14.3% to 38.9%. Published reports were available for several countries that did not provide GASP surveillance responses for ceftriaxone (n = 5) and azithromycin (n = 3) respectively. Over the study period, there was a 183% increase in the number of countries providing surveillance data for GASP for both ceftriaxone and azithromycin, and a 30.6% increase in ceftriaxone MIC testing across the Asia Pacific facilitated by this project.

CONCLUSION

This study provides the first comprehensive illustration of increasing MICs to ceftriaxone in the Asia Pacific. The survey and literature review additionally detail increasing resistance to azithromycin. Further surveillance system strengthening is required to monitor these trends in order to address and curb gonococcal AMR in the region.

Molecular Antimicrobial Resistance of Neisseria gonorrhoeae in a Moroccan Area

Objectives

To identify the prevalence and the types of Neisseria gonorrhoeae (NG) resistance plasmids-mediated penicillin (PPNG) and tetracycline (TRNG), the ciprofloxacin resistance (CRNG), and related risk factors of each types of resistance.

Methods

The beta-lactamase-producing plasmid types (Africa, Asia, and Toronto), tetM tetracycline resistance plasmid types (America and Dutch), and the determination of the Ser-91 mutation of GyrA were detected by specifics PCRs on 149 diagnosed NG positives samples followed by Hinf1 digestion for tetM and gyrA mutation.

Results

135 (90.1%) samples showed a profile of molecular resistance to at least one antibiotic with predominance of ciprofloxacin resistance. In fact, 36 (24.2%) and 69 (46.3%) cases harbored PPNG and TRNG, respectively, and 116 (77.9%) cases showed the mutation Ser-91 of GyrA (CRNG). From a total of 36 PPNG isolates, the Toronto, Asian, and Toronto/Asian types were detected in 13 (36.1%), 10 (27.8%), and 13 (36.1%) cases, respectively, whereas the African type was not detected. In addition, the American type of TRNG was detected in 92.8% (64/69) of cases, while the Dutch type was detected in 7.2% (5/69) of cases. The association of demographics and clinical variables with NG resistance to ciprofloxacin, penicillin, and tetracycline was studied and the risk factors have been determined.

Conclusion

Resistance to penicillin, tetracycline, and ciprofloxacin among NG samples positives remained at high levels in Morocco as determined by molecular profile. So, the use of molecular tools for NG antimicrobial resistance detection can help in the management and spread limitation of this infection.

Identifying factors that lead to the persistence of imported gonorrhoeae strains: a modelling study

OBJECTIVE

The importation of Neisseria gonorrhoeae (NG) strains from overseas is believed to be the main source of antimicrobial resistance in Australia. With recent sporadic cases of ceftriaxone-resistant gonorrhoea reported in Australia and elsewhere, we sought to model the potential for imported NG strains to persist in the men who have sex with men (MSM) population in Australia.

METHODS

We developed an individual-based model to simulate the transmission of NG in a population of urban MSM, and used this model to investigate factors contributing to the probability that an imported NG strain will persist.

RESULTS

The probability of the imported NG strain persisting as the result of a single importation event is less than 1%, but the probability increases to 1% if the imported NG strain is resistant to treatment, and further increases to 3.1% if the imported NG strain can also form mixed infections with the local NG strain. The probability of the imported NG strain persisting increases to 4.4% if there are at least three importation events per month within a 1-year period.

CONCLUSION

The imported NG strain is unlikely to persist as a result of a single importation event. However, the probability of persistence increases if the imported NG strain is resistant to treatment, can form mixed infections with the local NG strain or there are frequent importation events. Identification of the factors that determine the likelihood of persistence of an imported NG strain could contribute to our capacity to respond appropriately and in a timely fashion.

Mixed gonococcal infections in a high-risk population, Sydney, Australia 2015: implications for antimicrobial resistance surveillance?

OBJECTIVES

Previous studies have shown that mixed-strain gonococcal infections can occur. However, it remains unclear whether such infections impact upon the reliability of Neisseria gonorrhoeae antimicrobial resistance (AMR) surveillance. In this study, we aimed to resolve this question by intensively sampling isolates from gonorrhoea-positive specimens in a high-risk population in Sydney, Australia.

METHODS

A total of 615 N. gonorrhoeae isolates, originating from 63 clinical samples (31 rectal swabs and 32 throat swabs), were characterized. All isolates were subject to N. gonorrhoeae identification, antimicrobial susceptibility testing and genotyping by SNP-based MLST.

RESULTS

Only 2 of the 63 (3.2%) samples provided evidence of mixed-strain infections. These comprised two rectal swabs that harboured isolates of different SNP-based MLST genotypes; however, the AMR susceptibility profiles of the different genotypes from these samples were indistinguishable. Within-sample differences in the AMR susceptibility profiles were observed for a further seven samples; however, the differences were not considered significant; MIC values were typically within a 2-fold difference or were close to test breakpoints.

CONCLUSIONS

Results of this study provide further evidence that mixed-strain gonococcal infections do occur, although at low prevalence. Our data indicate that at a population level such infections are unlikely to impact significantly upon N. gonorrhoeae AMR surveillance.