Surveillance of gonococcal antimicrobial susceptibility resulting in early detection of emerging resistance

Antimicrobial Resistance in Gonorrhea

Antimicrobial resistance is a global public health emergency. The World Health Organization recently highlighted the growing number of new sexually transmitted infections such as gonorrhea, syphilis, and Chlamydia, which are resistant to common antibiotics. The phenomenon is also on the rise due to increasing intercontinental travel. Emerging antibiotic-resistant strains of gonorrhea are particularly associated with international spread from Southeast Asian travelers. Infection with Neisseria gonorrhoeae can cause a wide spectrum of associated diseases such as dermatitis, arthritis and septic arthritis, and pelvic inflammatory disease, and can even lead to serious health consequences for the individual. Natural infection confers no immunity, and vaccination is not available currently, although in several countries, it has been reported that the antimeningococcal vaccine may protect against gonorrhea. Implementing all necessary preventive measures is crucial, as well as appropriate and timely diagnostic methods and effective antimicrobial therapeutic treatments in the correct modalities to avoid the increase of forms of gonorrhea that are resistant to common antibiotics and difficult to eradicate.

Surveillance systems to monitor antimicrobial resistance in Neisseria gonorrhoeae: a global, systematic review, 1 January 2012 to 27 September 2020

Background

Effective surveillance of antimicrobial resistance (AMR) in Neisseria gonorrhoeae is required for the early detection of resistant strains and to ensure that treatment guidelines are appropriate for the setting in which they are implemented. AMR in N. gonorrhoeae has been identified as a global health threat.

Aim

We performed a systematic review to identify and describe surveillance systems targeting AMR in N. gonorrhoeae.

Methods

We searched Medline, PubMed, Global Health, EMBASE, CINAHL, Web of Science and ProQuest databases and grey literature between 1 January 2012 and 27 September 2020. Surveillance systems were defined as the continuous, systematic collection, analysis and interpretation of N. gonorrhoeae resistance data. The key components of surveillance systems were extracted, categorised, described and summarised.

Results

We found 40 publications reporting on N. gonorrhoeae AMR surveillance systems in 27 countries and 10 multi-country or global surveillance reports. The proportion of countries with surveillance systems in each of the WHO's six regions ranged from one of 22 countries in the Eastern Mediterranean and five of 54 in Africa, to three of 11 countries in South East Asia. Only four countries report systems which are both comprehensive and national. We found no evidence of a current surveillance system in at least 148 countries. Coverage, representativeness, volume, clinical specimen source, type and epidemiological information vary substantially and limit interpretability and comparability of surveillance data for public health action.

Conclusion

Globally, surveillance for N. gonorrhoeae AMR is inadequate and leaves large populations vulnerable to a major public health threat.

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.

Using the genetic characteristics of Neisseria gonorrhoeae strains with decreased susceptibility to cefixime to develop a molecular assay to predict cefixime susceptibility

BACKGROUND

In the last two decades, gonococcal strains with decreased cefixime susceptibility and cases of clinical treatment failure have been reported worldwide. Gonococcal strains with a cefixime minimum inhibitory concentration (MIC) ≥0.12 µg mL-1 are significantly more likely to fail cefixime treatment than strains with an MIC <0.12 µg mL-1. Various researchers have described the molecular characteristics of gonococcal strains with reduced cefixime susceptibility, and many have proposed critical molecular alterations that contribute to this decreased susceptibility.

METHODS

A systematic review of all published articles in PubMed through 1 November 2018 was conducted that report findings on the molecular characteristics and potential mechanisms of resistance for gonococcal strains with decreased cefixime susceptibility. The findings were summarised and suggestions were made for the development of a molecular-based cefixime susceptibility assay.

RESULTS

The penicillin-binding protein 2 (PBP2) encoded by the penA gene is the primary target of cefixime antimicrobial activity. Decreased cefixime susceptibility is conferred by altered penA genes with mosaic substitute sequences from other Neisseria (N.) species (identifiable by alterations at amino acid position 375-377) or by non-mosaic penA genes with at least one of the critical amino acid substitutions at positions 501, 542 and 551. Based on this review of 415 international cefixime decreased susceptible N. gonorrhoeae isolates, the estimated sensitivity for an assay detecting the aforementioned amino acid alterations would be 99.5% (413/415).

CONCLUSIONS

Targeting mosaic penA and critical amino acid substitutions in non-mosaic penA are necessary and may be sufficient to produce a robust, universal molecular assay to predict cefixime susceptibility.

Antibiotic Susceptibility Monitoring of Neisseria gonorrhoeae in Bacolod City, Philippines

A local study was conducted to monitor the antibiotic susceptibility of N. gonorrhoeae in Bacolod City, Philippines. A total of 88 isolates were taken during the period of 1 January 2015 to 30 June 2017, from male patients ages 12 to 72 years. The highest incidence of gonorrhea infection was in the group aged 20⁻24 years (34.09%). The susceptibility pattern to antibiotics was as follows: ceftriaxone 100%, cefixime 82.6%, spectinomycin 92.1%, ciprofloxacin 4.9%, tetracycline 5.1%, and penicillin G with 0%. All isolates were noted to produce beta-lactamase, which can be attributed to plasmid-mediated penicillin resistance. These findings indicate that the resistance rates of N. gonorrhoeae to most commonly-used antibiotics are increasing, and that ceftriaxone remains an effective antibiotic in treating gonorrhea infections locally.

Management of Gonorrhea in Adolescents and Adults in the United States

Gonorrhea is the second most commonly reported notifiable disease in the United States and is associated with serious health sequelae, including pelvic inflammatory disease, infertility, and ectopic pregnancy. Treatment for gonorrhea has been complicated by antimicrobial resistance. Neisseria gonorrhoeae has developed resistance to each of the antimicrobials that were previously recommended as first-line treatment regimens, and current treatment options are severely limited. This article summarizes the key questions and data that were discussed at the Sexually Transmitted Diseases (STD) Treatment Guidelines Expert Consultation meeting in April 2013, and the rationale for the 2015 Centers for Disease Control and Prevention STD treatment guidelines for gonococcal infections in adolescents and adults. Key issues addressed include whether to change the dosage of ceftriaxone and azithromycin used in the recommended dual treatment regimen, whether to continue to list dual treatment with cefixime and azithromycin as an alternative treatment regimen, and management of gonococcal infections in persons with severe cephalosporin allergy or suspected treatment failure.

On the pathway to better birth outcomes? A systematic review of azithromycin and curable sexually transmitted infections

The WHO recommends the administration of sulfadoxine-pyrimethamine (SP) to all pregnant women living in areas of moderate (stable) to high malaria transmission during scheduled antenatal visits, beginning in the second trimester and continuing to delivery. Malaria parasites have lost sensitivity to SP in many endemic areas, prompting the investigation of alternatives that include azithromycin-based combination (ABC) therapies. Use of ABC therapies may also confer protection against curable sexually transmitted infections and reproductive tract infections (STIs/RTIs). The magnitude of protection at the population level would depend on the efficacy of the azithromycin-based regimen used and the underlying prevalence of curable STIs/RTIs among pregnant women who receive preventive treatment. This systematic review summarizes the efficacy data of azithromycin against curable STIs/RTIs.