Public health measures to control the spread of antimicrobial resistance in Neisseria gonorrhoeae in men who have sex with men

Gonorrhoea is one of the most common sexually transmitted infections. The control of gonorrhoea is extremely challenging because of the repeated development of resistance to the antibiotics used for its treatment. We explored different strategies to control the spread of antimicrobial resistance and prevent increases in gonorrhoea prevalence. We used a mathematical model that describes gonorrhoea transmission among men who have sex with men and distinguishes gonorrhoea strains sensitive or resistant to three antibiotics. We investigated the impact of combination therapy, switching first-line antibiotics according to resistance thresholds, and other control efforts (reduced sexual risk behaviour, increased treatment rate). Combination therapy can delay the spread of resistance better than using the 5% resistance threshold. Increased treatment rates, expected to enhance gonorrhoea control, may reduce gonorrhoea prevalence only in the short term, but could lead to more resistance and higher prevalence in the long term. Re-treatment of resistant cases with alternative antibiotics can substantially delay the spread of resistance. In conclusion, combination therapy and re-treatment of resistant cases with alternative antibiotics could be the most effective strategies to prevent increases in gonorrhoea prevalence due to antimicrobial resistance.

Changing antimicrobial resistance profiles among Neisseria gonorrhoeae isolates in Italy, 2003 to 2012

The emergence of Neisseria gonorrhoeae isolates displaying resistance to antimicrobial agents is a major public health concern and a serious issue related to the occurrence of further untreatable gonorrhea infections. A retrospective analysis on 1,430 N. gonorrhoeae isolates, collected from 2003 through 2012, for antimicrobial susceptibility by Etest and molecular characterization by Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) was carried out in Italy. Azithromycin-resistant gonococci decreased from 14% in 2007 to 2.2% in 2012. Similarly, isolates with high MICs to cefixime (>0.125 mg/liter) decreased from 11% in 2008 to 3.3% in 2012. The ciprofloxacin resistance rate remains quite stable, following an increasing trend up to 64% in 2012. The percentage of penicillinase-producing N. gonorrhoeae (PPNG) significantly declined from 77% in 2003 to 7% in 2012. A total of 81 multidrug-resistant (MDR) gonococci were identified, showing 11 different antimicrobial resistance patterns. These were isolated from men who have sex with men (MSM) and from heterosexual patients. Two sequence types (STs), ST661 and ST1407, were the most common. Genogroup 1407, which included cefixime-, ciprofloxacin-, and azithromycin-resistant isolates, was found. In conclusion, a change in the antimicrobial resistance profiles among gonococci was identified in Italy together with a percentage of MDR isolates.

In vitro activities of the novel bicyclolides modithromycin (EDP-420, EP-013420, S-013420) and EDP-322 against MDR clinical Neisseria gonorrhoeae isolates and international reference strains

OBJECTIVES

New antimicrobials are essential to prevent gonorrhoea becoming an untreatable infection. Herein, the in vitro activities of the novel bicyclolides modithromycin (EDP-420, EP-013420, S-013420) and EDP-322 against Neisseria gonorrhoeae strains were investigated and compared with antimicrobials currently or previously recommended for treatment of gonorrhoea.

METHODS

MICs (mg/L) were determined using an agar dilution method (modithromycin and EDP-322) or Etest (seven antimicrobials) for a large geographically, temporally and genetically diverse collection of clinical N. gonorrhoeae isolates (n = 225) and international reference strains (n = 29), including diverse MDR and XDR isolates.

RESULTS

The MIC range, modal MIC, MIC50 and MIC90 of modithromycin and EDP-322 were 0.004-256, 0.25, 0.25 and 1 mg/L and 0.008-16, 0.5, 0.5 and 1 mg/L, respectively. The activities of modithromycin and EDP-322 were mainly superior to those of azithromycin and additional antimicrobials investigated. In general, there was no cross-resistance with other antimicrobials.

CONCLUSIONS

Modithromycin and EDP-322 exhibited high levels of in vitro activities against N. gonorrhoeae, including isolates resistant to azithromycin, cefixime, ceftriaxone, spectinomycin, ampicillin, tetracycline and ciprofloxacin. However, some cross-resistance with high-level azithromycin resistance (MIC = 4096 mg/L) was observed. Modithromycin and EDP-322 could be effective options for treatment of gonorrhoea, particularly for cases resistant to extended-spectrum cephalosporins and as a part of an antimicrobial combination therapy regimen. Nevertheless, it is important to detail the in vitro selection, in vivo emergence and mechanisms of resistance, pharmacokinetics/pharmacodynamics in humans and optimal dosing, and perform appropriate randomized controlled clinical trials.

Identification of sRNAs expressed by the human pathogen Neisseria gonorrhoeae under disparate growth conditions

In the last several years, bacterial gene regulation via small RNAs (sRNAs) has been recognized as an important mechanism controlling expression of essential proteins that are critical to bacterial growth and metabolism. Technologies such as RNA-seq are rapidly expanding the field of sRNAs and are enabling a global view of the “sRNAome” of several bacterial species. While numerous sRNAs have been identified in a variety of both Gram-negative and Gram-positive bacteria, only a very small number have been fully characterized in the human pathogen Neisseria gonorrhoeae, the etiological agent of the STD gonorrhea. Here we present the first analysis of N. gonorrhoeae specifically focused on the identification of sRNAs through RNA-seq analysis of the organism cultured under different in vitro growth conditions. Using a new computational program, Rockhopper, to analyze prokaryotic RNA-seq data obtained from N. gonorrhoeae we identified several putative sRNAs and confirmed their expression and size through Northern blot analysis. In addition, RNA was collected from four different growth conditions (iron replete and deplete, as well as with and without co-culture with human endocervical cells). Many of the putative sRNAs identified shoed varying expression levels relative to the different growth conditions examine or were detected only under certain conditions but not others. Comparisons of identified sRNAs with the regulatory pattern of putative mRNA targets revealed possible functional roles for these sRNAs. These studies are the first to carry out a global analysis of N. gonorrhoeae specifically focused on sRNAs and show that RNA-mediated regulation may be an important mechanism of gene control in this human pathogen.

Gonococcal infections and emergence of gonococcal decreased susceptibility to cephalosporins in France, 2001 to 2012

Resistance to cephalosporins may lead to untreatable gonococcal infections. We describe the results of the sentinel surveillance of gonococcal infections and the evolution of the resistance of Neisseria gonorrhoeae to antibiotics in France from 2001 to 2012. We also analyse the factors associated with decreased susceptibility to third generation cephalosporins. In France, surveillance of gonococcal infections is conducted through a network of voluntarily participating laboratories. Strains are sent to the national reference laboratory to determine the minimum inhibitory concentration (MIC) for six antibiotics. During the study period, the number of gonococcal infections increased steadily. The susceptibility of 8,649 strains was studied for this period. The proportion of strains with decreased susceptibility to cefixime (MIC>0.125 mg/L) quadrupled between 2011 (0.7%:10/1,521) and 2012 (3.0%: 33/1,093; p<0.001). Between 2001 and 2012, only two of the 8,649 strains, both collected in 2010, had a MIC>0.125 mg/L for ceftriaxone. Decreased susceptibility to cephalosporins increased with older age and was more common in pharyngeal strains. Decreased susceptibility to cefixime may indicate that the national recommendation to use ceftriaxone as a first line treatment for cases of urethritis and cervicitis has not been fully implemented. Enhanced surveillance of pharyngeal strains is strongly suggested.

Characterisation of blaTEM genes and types of β-lactamase plasmids in Neisseria gonorrhoeae - the prevalent and conserved blaTEM-135 has not recently evolved and existed in the Toronto plasmid from the origin

Background

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern worldwide. It has been recently feared that the bla_TEM-1 gene is, via bla_TEM-135, evolving into an extended-spectrum β-lactamase (ESBL), which could degrade all cephalosporins including ceftriaxone. The aims of the present study were to characterize the bla_TEM genes, types of β-lactamase plasmids, the degradation of ampicillin by TEM-135 compared to TEM-1, and to perform molecular epidemiological typing of β-lactamase-producing N. gonorrhoeae strains internationally.

Methods

β-lactamase producing N. gonorrhoeae isolates (n = 139) cultured from 2000 to 2011 in 15 countries were examined using antibiograms, bla_TEM gene sequencing, β-lactamase plasmid typing, and N. gonorrhoeae multiantigen sequence typing (NG-MAST). Furthermore, the bla_TEM gene was sequenced in the first described Toronto plasmid (pJD7), one of the first Asian plasmids (pJD4) and African plasmids (pJD5) isolated in Canada. The degradation of ampicillin by TEM-135 compared to TEM-1 was examined using a MALDI-TOF MS hydrolysis assay.

Results

Six different bla_TEM sequences were identified (among isolates with 125 different NG-MAST STs), i.e. bla_TEM-1 (in 104 isolates), bla_TEM-135 (in 30 isolates), and four novel bla_TEM sequences (in 5 isolates). The bla_TEM-1 allele was only found in the African and Asian plasmids, while all Rio/Toronto plasmids possessed the bla_TEM-135 allele. Most interesting, the first described gonococcal Toronto plasmid (pJD7), identified in 1984, also possessed the highly conserved bla_TEM-135 allele. The degradation of ampicillin by TEM-135 compared to TEM-1 was indistinguishable in the MALDI-TOF MS hydrolysis assay.

Conclusions

bla_TEM-135, encoding TEM-135, is predominantly and originally associated with the Rio/Toronto plasmid and prevalent among the β-lactamase producing gonococcal strains circulating globally. bla_TEM-135 does not appear, as previously hypothesized, to have recently evolved due to some evolutionary selective pressure, for example, by the extensive use of extended-spectrum cephalosporins worldwide. On the contrary, the present study shows that bla_TEM-135 existed in the Toronto plasmid from its discovery and that bla_TEM-135 is highly conserved (not further evolved in the past >30 years). Nevertheless, international studies for monitoring the presence of different bla_TEM alleles, the possible evolution of the bla_TEM-135 allele, and the types of β-lactamase producing plasmids, remain imperative.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-454) contains supplementary material, which is available to authorized users.

Verified clinical failure with cefotaxime 1g for treatment of gonorrhoea in the Netherlands: a case report

We describe the first case of treatment failure of gonorrhoea with a third generation cephalosporin, cefotaxime 1g intramuscularly, in the Netherlands. The case was from a high-frequency transmitting population (men having sex with men) and was caused by the internationally spreading multidrug-resistant gonococcal NG-MAST ST1407 clone. The patient was clinically cured after treatment with ceftriaxone 500 mg intramuscularly and this is the only third generation cephalosporin that should be used for first-line empiric treatment of gonorrhoea. Increased awareness of failures with third generation cephalosporins, enhanced monitoring and appropriate verification of treatment failures including more frequent test-of-cures, and strict adherence to regularly updated treatment guidelines are essential globally.

Incidence and antimicrobial susceptibility of Neisseria gonorrhoeae isolates from patients attending the national Neisseria gonorrhoeae reference laboratory of Hungary

Background

The Hungarian national guidelines for the treatment of gonorrhoea were published in 2002 but are now widely considered to be outdated. Improved knowledge is needed with respect to the epidemiology and antimicrobial susceptibility of Neisseria gonorrhoeae strains currently circulating in Hungary not least for the construction of updated local recommendations for treating gonorrhoea. European guidelines are based mostly on western European data raising concerns locally that recommended treatments might not be optimised for the situation in Hungary. We report our recent study on the distribution of antibiotic resistance in various Hungarian (East European) Neisseria gonorrhoeae strains isolated from patients with gonorrhoea over the past four years.

Methods

Between January 2010 and December 2013, isolates of N. gonorrhoeae were obtained from sexually active individuals during medical examination at the STD Center of Semmelweis University in Budapest. The minimal inhibitory concentrations (MIC) of azithromycin, cefixime, ceftriaxone, ciprofloxacin, penicillin, tetracycline and spectinomycin were determined to establish the antimicrobial susceptibility of the strains currently circulating in patients that attend our clinic.

Results

Among the 9097 patients tested, 582 had an N. gonorrhoeae infection as detected by culture. The isolates were all sensitive to ceftriaxone and spectinomycin and 581/582 strains were sensitive to cefixime. In contrast, the number of detected strains with elevated azithromycin MIC did increase over the time period examined to approximately 16% in 2013. There was a high percentage of detected resistance to penicillin (77%), tetracycline (86%), and ciprofloxacin (66%) in the isolates examined in this study.

Conclusion

Current European guidelines recommend 2 g azithromycin in addition to 500 mg ceftriaxone as first choice therapy for gonorrhoea. For the purposes of revising the Hungarian national treatment guidelines, apparent increasing resistance to azithromycin during the last four years should be accounted for. It is also clear that penicillin, tetracycline and ciprofloxacin are inappropriate treatment measures at least locally. We also recommend that culture should form part of the diagnostic pathway of gonorrhoea, followed by antibiotic susceptibility testing with MIC determination. This will provide valuable continued monitoring of antibiotic resistance development in strains of Neisseria gonorrhoeae circulating in Hungary.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-433) contains supplementary material, which is available to authorized users.

First antimicrobial resistance data and genetic characteristics of Neisseria gonorrhoeae isolates from Estonia, 2009-2013

Gonorrhoea is a sexually transmitted infection with major public health implications and Neisseria gonorrhoeae has developed resistance to all antimicrobials introduced for treatment. Enhanced surveillance of antimicrobial resistance in N. gonorrhoeae is crucial globally. This is the first internationally reported antimicrobial resistance data for N. gonorrhoeae from Estonia (44 isolates cultured in 2009–2013). A high prevalence of resistance was observed for azithromycin, ciprofloxacin and tetracycline. One and two isolates with resistance and decreased susceptibility to the last remaining first-line treatment option ceftriaxone, respectively, were identified. It is crucial to implement surveillance of gonococcal antimicrobial resistance (ideally also treatment failures) in Estonia.

Four treatment failures of pharyngeal gonorrhoea with ceftriaxone (500 mg) or cefotaxime (500 mg), Sweden, 2013 and 2014

We describe four cases in Sweden of verified treatment failures of pharyngeal gonorrhoea with ceftriaxone (500 mg; n=3) or cefotaxime (500 mg; n=1) monotherapy. All the ceftriaxone treatment failures were caused by the internationally spreading multidrug-resistant gonococcal NG-MAST genogroup 1407 clone. Increased awareness of treatment failures is crucial particularly when antimicrobial monotherapy is used. Frequent test of cure and appropriate verification/falsification of suspected treatment failures, as well as implementation of recommended dual antimicrobial therapy are imperative.

Global resistance of Neisseria gonorrhoeae: when theory becomes reality

PURPOSE OF REVIEW

Neisseria gonorrhoeae has demonstrated a remarkable genetic capacity to acquire antimicrobial resistance (AMR) determinants. This review focuses on the recent developments in respect of third generation extended spectrum cephalosporin (ESC)-resistant gonorrhoea and the search for future treatment options.

RECENT FINDINGS

The estimated incidence of new gonorrhoea cases is increasing, and the antimicrobial resistance profile of N. gonorrhoeae is worsening. The most significant recent finding has been the emergence of extensively drug-resistant (XDR) N. gonorrhoeae characterized by very high ceftriaxone minimum inhibitory concentrations. A national switch from cefixime to high-dose ceftriaxone as first-line antigonococcal therapy in England and Wales, as well as parts of Japan, has been accompanied by a reduction in the prevalence of oral ESC-resistant gonococci. Azithromycin given in combination with either gentamicin or gemifloxacin has been shown to be an effective alternative antigonococcal therapy. Both ertapenem and solithromycin have good in-vitro activity against ESC-resistant N. gonorrhoeae strains.

SUMMARY

Current strategies to control gonococcal AMR should focus on the use of higher doses of ceftriaxone given as part of dual therapy and further evaluation of alternative drug combinations. The emergence of XDR gonorrhoea argues for enhanced efforts to develop novel antimicrobial agents and a gonococcal vaccine.

The efficacy and safety of gentamicin plus azithromycin and gemifloxacin plus azithromycin as treatment of uncomplicated gonorrhea

BACKGROUND

Ceftriaxone is the foundation of currently recommended gonorrhea treatment. There is an urgent need for backup treatment options for patients with cephalosporin allergy or infections due to suspected cephalosporin-resistant Neisseria gonorrhoeae. We evaluated the efficacy and tolerability of 2 combinations of existing noncephalosporin antimicrobials for treatment of patients with urogenital gonorrhea.

METHODS

We conducted a randomized, multisite, open-label, noncomparative trial in 5 outpatient sexually transmitted disease clinic sites in Alabama, California, Maryland, and Pennsylvania. Patients aged 15-60 years diagnosed with uncomplicated urogenital gonorrhea were randomly assigned to either gentamicin 240 mg intramuscularly plus azithromycin 2 g orally, or gemifloxacin 320 mg orally plus azithromycin 2 g orally. The primary outcome was microbiological cure of urogenital infections (negative follow-up culture) at 10-17 days after treatment among 401 participants in the per protocol population.

RESULTS

Microbiological cure was achieved by 100% (lower 1-sided exact 95% confidence interval [CI] bound, 98.5%) of 202 evaluable participants receiving gentamicin/azithromycin, and 99.5% (lower 1-sided exact 95% CI bound, 97.6%) of 199 evaluable participants receiving gemifloxacin/azithromycin. Gentamicin/azithromycin cured 10 of 10 pharyngeal infections and 1 of 1 rectal infection; gemifloxacin/azithromycin cured 15 of 15 pharyngeal and 5 of 5 rectal infections. Gastrointestinal adverse events were common in both arms.

CONCLUSIONS

Gentamicin/azithromycin and gemifloxacin/azithromycin were highly effective for treatment of urogenital gonorrhea. Gastrointestinal adverse events may limit routine use. These non-cephalosporin-based regimens may be useful alternative options for patients who cannot be treated with cephalosporin antimicrobials. Additional treatment options for gonorrhea are needed. Clinical Trials Registration. NCT00926796.

Antimicrobial resistance, genetic resistance determinants for ceftriaxone and molecular epidemiology of Neisseria gonorrhoeae isolates in Nanjing, China

OBJECTIVES

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major problem worldwide. This study investigated the AMR, genetic ceftriaxone resistance determinants and molecular epidemiology of N. gonorrhoeae in Nanjing, China.

METHODS

N. gonorrhoeae isolates were collected in 2007 (n = 198) and 2012 (n = 80). The susceptibility to ceftriaxone, spectinomycin, ciprofloxacin and tetracycline was determined using an agar-dilution method. The ceftriaxone resistance determinants penA, mtrR and penB were examined using sequencing. N. gonorrhoeae multi-antigen sequence typing (NG-MAST) was performed for molecular epidemiology.

RESULTS

All isolates were resistant to ciprofloxacin, 42.4% produced β-lactamase and 34.9% showed high-level resistance to tetracycline (MIC ≥16 mg/L). In total, 5.4% of isolates were resistant to ceftriaxone; however, all of these isolates were obtained in 2007 and the susceptibility to ceftriaxone appeared to have increased. All isolates were susceptible to spectinomycin. No penA mosaic alleles were found. Non-mosaic penA alleles with A501T and G542S alterations, an H105Y alteration in mtrR and an A102D/N alteration in porB1b were statistically associated with decreased susceptibility or resistance to ceftriaxone. The most prevalent NG-MAST sequence types (STs) were ST568 (n = 13), ST270 (n = 9) and ST421 (n = 7). ST270 was the most common ST in isolates with decreased susceptibility or resistance to ceftriaxone.

CONCLUSIONS

Ceftriaxone, ideally 500 mg and together with azithromycin (1-2 g), should be recommended for treatment of gonorrhoea in Nanjing, China. However, N. gonorrhoeae strains with resistance to ceftriaxone have been found in Nanjing. NG-MAST and ceftriaxone resistance determinant analysis can be valuable to supplement the antimicrobial resistance surveillance in China, which needs to be further strengthened.

High in vitro activity of the novel spiropyrimidinetrione AZD0914, a DNA gyrase inhibitor, against multidrug-resistant Neisseria gonorrhoeae isolates suggests a new effective option for oral treatment of gonorrhea

We evaluated the activity of the novel spiropyrimidinetrione AZD0914 (DNA gyrase inhibitor) against clinical gonococcal isolates and international reference strains (n=250), including strains with diverse multidrug resistance and extensive drug resistance. The AZD0914 MICs were substantially lower than those of most other currently or previously recommended antimicrobials. AZD0914 should be further evaluated, including in vitro selection, in vivo emergence and mechanisms of resistance, pharmacokinetics/pharmacodynamics in humans, optimal dosing, and performance, in appropriate randomized and controlled clinical trials.

Russian gonococcal antimicrobial susceptibility programme (RU-GASP)--resistance in Neisseria gonorrhoeae during 2009-2012 and NG-MAST genotypes in 2011 and 2012

Background

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major concern worldwide and gonococcal AMR surveillance globally is imperative for public health purposes. In Eastern Europe, gonococcal AMR surveillance is exceedingly rare. However, in 2004 the Russian gonococcal antimicrobial susceptibility programme (RU-GASP) was initiated. The aims of this study were to describe the prevalence and trends of gonococcal AMR from 2009 to 2012, and molecular epidemiological genotypes in 2011 and 2012 in Russia.

Methods

Gonococcal isolates from 12–46 surveillance sites distributed across Russia, obtained in 2009 (n = 1200), 2010 (n = 407), 2011 (n = 423), and 2012 (n = 106), were examined for antimicrobial susceptibility using agar dilution method. Gonococcal isolates from 2011 and 2012 were investigated with N. gonorrhoeae multi-antigen sequence typing (NG-MAST).

Results

During 2009–2012, the proportions of gonococcal isolates resistant to ciprofloxacin, penicillin G, azithromycin and spectinomycin ranged from 25.5% to 44.4%, 9.6% to 13.2%, 2.3% to 17.0% and 0.9% to 11.6%, respectively. Overall, the resistance level to penicillin G was stable, the resistance level to ciprofloxacin was decreasing, however, the level of resistance to azithromycin increased. All isolates were susceptible to ceftriaxone using the US CLSI breakpoints. However, using the European breakpoints 58 (2.7%) of the isolates were resistant to ceftriaxone. Interestingly, this proportion was decreasing, i.e. from 4.8% in 2009 to 0% in 2012.

Conclusions

In Russia, the diversified gonococcal population showed a high resistance to ciprofloxacin, penicillin G and azithromycin. In general, the MICs of ceftriaxone were relatively high, however, they were decreasing from 2009 to 2012. Ceftriaxone should be the first-line for empiric antimicrobial monotherapy of gonorrhoea in Russia. It is essential to further strengthen the surveillance of gonococcal AMR (ideally also gonorrhoea treatment failures) in Russia.

Prevalence and molecular epidemiological typing of penicillinase-producing Neisseria gonorrhoeae and their bla(TEM-135) gene variants in Nanjing, China

BACKGROUND

This study aimed to investigate the prevalence of penicillinase-producing Neisseria gonorrhoeae (PPNG) and their blaTEM-135 gene variant in 2007 and 2012 in Nanjing, China. In addition, molecular epidemiological typing of all isolates was performed to elucidate the genetic relationships of the PPNG strains.

METHODS

A total of 199 and 77 N. gonorrhoeae isolates were collected at the National Center for STD Control in 2007 and 2012, respectively. Nitrocefin tests were performed to identify PPNG. Mismatch amplification mutation assay was used to identify blaTEM-135. All isolates were genotyped using N. gonorrhoeae multiantigen sequence typing (NG-MAST), and additionally, porB-based phylogenetic analysis was performed for the PPNG isolates.

RESULTS

The total prevalence of PPNG isolates was 41% (114/276) and 58% (66/114) of these PPNG isolates possessed bla(TEM-135). In 2007, 45% (90/199) produced β-lactamase, and of those PPNG, 58% (52/90) possessed bla(TEM-135). In 2012, 31% (24/77) were PPNG, and 58% (14/24) of those isolates contained bla(TEM-135). There were 162 NG-MAST STs among the 276 isolates, and 89 of those were novel STs. A strong association between specific NG-MAST STs and bla(TEM-135) was found, and the porB-based phylogenetic analysis showed a distant evolutionary relationship between isolates in 2007 and isolates in 2012.

CONCLUSIONS

A high prevalence of PPNG and blaTEM-135 was found in Nanjing, China. bla(TEM-135) might be a precursor in the evolution into an extended-spectrum β-lactamase that can degrade ceftriaxone, which stresses the need to continuously monitor PPNG, blaTEM-135, and additional evolving blaTEM gene variants.

Azithromycin resistance is coevolving with reduced susceptibility to cephalosporins in Neisseria gonorrhoeae in Ontario, Canada

Azithromycin (AZM) is routinely recommended as a component of dual therapy for gonorrhea in combination with third-generation cephalosporins (3GC). In this study, we examined the prevalence of AZM-resistant (AZM(r)) Neisseria gonorrhoeae from July 2010 to February 2013, assessed the rate of concurrent cephalosporin resistance under the current treatment recommendations, and analyzed the clonal distribution of AZM(r) isolates in Ontario, Canada. Nineteen AZM(r) clinical isolates (one per patient; MIC, ≥2 μg/ml) were included in the study. Susceptibility profiles of these isolates to 11 antibiotics, molecular typing, characterization of macrolide resistance mechanisms, and penicillin-binding protein 2 (PBP2) patterns were determined for all the isolates. Two groups were defined based on AZM(r) level; group A isolates displayed high-level resistance (MIC, ≥2,048 μg/ml) due to mutations (A2143G) in the four copies of the 23S rRNA rrl gene, and group B isolates had moderate resistance to AZM (MICs, 2 to 8 μg/ml, C2599T mutation in the rrl gene), with a subgroup belonging to sequence type 3158 (ST3158) (n = 8), which also showed reduced susceptibility to 3GC (MICs, 0.12 to 0.25 μg/ml, PBP2 pattern XXXIV). This AZM(r) phenotype was not observed in previous provincial surveillance in 2008 (the ST3158 clone was found, with AZM MICs of 0.25 to 0.5 μg/ml associated with mtrR mutations). We hypothesized that the AZM mutant prevention concentration (MPC) in the ST3158 subpopulation we found in 2008 was higher than the MPC in wild-type isolates (AZM MIC, ≤0.031 μg/ml), increasing the chances of additional selection of AZM(r) mutations. Full AZM resistance is now emerging in this clone together with reduced susceptibility to 3GC, threatening the future efficacy of these antibiotics as therapeutic options for treatment of gonorrhea.

Importance of multidrug efflux pumps in the antimicrobial resistance property of clinical multidrug-resistant isolates of Neisseria gonorrhoeae

The contribution of drug efflux pumps in clinical isolates of Neisseria gonorrhoeae that express extensively drug-resistant or multidrug-resistant phenotypes has heretofore not been examined. Accordingly, we assessed the effect on antimicrobial resistance of loss of the three gonococcal efflux pumps associated with a known capacity to export antimicrobials (MtrC-MtrD-MtrE, MacA-MacB, and NorM) in such clinical isolates. We report that the MIC of several antimicrobials, including seven previously and currently recommended for treatment was significantly impacted.

High in vitro activity of a novel dual bacterial topoisomerase inhibitor of the ATPase activities of GyrB and ParE (VT12-008911) against Neisseria gonorrhoeae isolates with various high-level antimicrobial resistance and multidrug resistance

OBJECTIVES

Clinical resistance to the currently recommended extended-spectrum cephalosporins (ESCs), the last remaining options for empirical antimicrobial monotherapy of gonorrhoea globally, has been reported. New antimicrobials are essential to avoid the emergence of untreatable gonorrhoea. We have investigated the in vitro activity of a novel dual bacterial topoisomerase inhibitor of the ATPase activities of GyrB and ParE (Vertex aminobenzimidazole VT12-008911), compared with antimicrobials currently or previously recommended for gonorrhoea treatment.

METHODS

MICs were determined using agar dilution (VT12-008911) or Etest (seven antimicrobials) for international reference strains (n = 28) and clinical Neisseria gonorrhoeae isolates (n = 220). The latter included three extensively drug-resistant isolates with high-level ceftriaxone resistance, additional isolates with clinical ESC resistance and a high number of isolates with ciprofloxacin resistance and multidrug resistance.

RESULTS

The MIC(50), MIC(90) and MIC range of VT12-008911 were 0.064, 0.125 and ≤0.002-0.25 mg/L, respectively. One-hundred and seventy (69%) isolates were ciprofloxacin resistant; however, only 54 of those isolates had a VT12-008911 MIC >0.064 mg/L (47 and 7 with MIC = 0.125 mg/L and MIC = 0.25 mg/L, respectively). The in vitro activity of VT12-008911 was superior to that of ciprofloxacin and all additional antimicrobials investigated. Time-kill curve analysis showed that VT12-008911 exhibited potent time-dependent bactericidal activity, at or very close to the MIC, against N. gonorrhoeae.

CONCLUSIONS

In vitro results suggest that VT12-008911 might be an effective treatment option for gonorrhoea. However, it will be important to detail the pharmacokinetics/pharmacodynamics, toxicity, selection and mechanisms of VT12-008911 resistance in N. gonorrhoeae and, finally, to perform well-designed in vivo randomized clinical trials.

Characterization of Neisseria gonorrhoeae isolates detected in Switzerland (1998-2012): emergence of multidrug-resistant clones less susceptible to cephalosporins

BACKGROUND

The spread of Neisseria gonorrhoeae (Ng) isolates resistant to the clinically implemented antibiotics is challenging the efficacy of treatments. Unfortunately, phenotypic and molecular data regarding Ng detected in Switzerland are scarce.

METHODS

We compared the characteristics of Ng detected during 1998-2001 (n = 26) to those detected during 2009-2012 (n = 34). MICs were obtained with the Etest and interpreted as non-susceptible (non-S) according to EUCAST criteria. Sequence type (ST) was achieved implementing the NG-MAST. BlaTEM, ponA, penA, mtrR, penB, tet(M), gyrA, parC, mefA, ermA/B/C/F, rplD, rplV, and 23S rRNA genes were analyzed.

RESULTS

The following susceptibility results were obtained (period: % of non-S, MIC90 in mg/L): penicillin (1998-2001: 42.3%, 3; 2009-2012: 85.3%, 16), cefixime (1998-2001: 0%, ≤0.016; 2009-2012: 8.8%, 0.125), ceftriaxone (1998-2001: 0%, 0.004; 2009-2012: 0%, 0.047), ciprofloxacin (1998-2001: 7.7%, 0.006; 2009-2012: 73.5%, ≥32), azithromycin (1998-2001: 11.5%, 0.25; 2009-2012: 23.6%, 0.38), tetracycline (1998-2001: 65.4%, 12; 2009-2012: 88.2%, 24), spectinomycin (1998-2001: 0%, 12; 2009-2012: 0%, 8). The prevalence of multidrug-resistant (MDR) isolates increased from 7.7% in 1998-2001 to 70.6% in 2009-2012. International STs and genogroups (G) emerged during 2009-2012 (G1407, 29.4%; G2992, 11.7%; G225, 8.8%). These isolates possessed distinctive mechanisms of resistance (e.g., G1407: PBP1 with L421, PBP2 pattern XXXIV, GyrA with S91F and D95G, ParC with S87R, PorB with G120K and A121N, mtrR promoter with A deletion).

CONCLUSIONS

The prevalence of penicillin- ciprofloxacin- and tetracycline-resistant Ng has reached dramatic levels, whereas cefixime and ceftriaxone show MICs that tend to increase during time. International MDR clones less susceptible to cephalosporins are rapidly emerging indicating that the era of untreatable gonococcal infections is close.

Phenotypic and molecular characterization of Neisseria gonorrhoeae isolates from Slovenia, 2006-12: rise and fall of the multidrug-resistant NG-MAST genogroup 1407 clone?

OBJECTIVES

To determine the phenotypic and molecular characteristics of Neisseria gonorrhoeae isolates obtained between 2006 and 2012 in Slovenia.

METHODS

Gonococcal isolates obtained between 2006 and 2012 in Slovenia (n = 194) were investigated with Etest for susceptibility to cefixime, ceftriaxone, penicillin, ciprofloxacin, azithromycin, tetracycline, gentamicin and spectinomycin. All isolates were examined with N. gonorrhoeae multiantigen sequence typing for molecular epidemiology and sequencing of the major extended-spectrum cephalosporin (ESC) resistance determinants (penA, mtrR and penB) was performed.

RESULTS

The overall prevalence of decreased susceptibility or resistance to cefixime and ceftriaxone (MIC ≥0.125 mg/L) was 11% and 5%, respectively. The decreased susceptibility or resistance showed an epidemic peak in 2011 (33% for cefixime and 11% for ceftriaxone), decreasing to 6% and 4%, respectively, in 2012. ST1407 (9% of isolates), ST21 (6%) and ST225 (6%) were the most common sequence types (STs) during 2006-12. Genogroup G1407 (ST1407 most prevalent ST), an internationally spread clone with decreased susceptibility or resistance to ESCs, was most prevalent (48%) in 2009. However, the G1407 prevalence then declined: in 2010, 30%; in 2011, 28%; and in 2012, 8%. Instead, in 2012 the ESC- and ciprofloxacin-susceptible G21 was the predominant genogroup (26%).

CONCLUSIONS

The prevalence of gonococcal resistance to ESCs in Slovenia has been high, but fluctuating. Fortunately, in 2012 some ESC- and ciprofloxacin-susceptible clones, such as genogroups G21, G1195 and G2992, appeared to have mainly replaced the multidrug-resistant G1407 clone, a replacement also seen in several European countries.

Molecular approaches to enhance surveillance of gonococcal antimicrobial resistance

The best available data indicate that the world is heading towards a pandemic of extensively drug-resistant Neisseria gonorrhoeae. At the same time, clinical microbiology laboratories have moved away from using culture-based methods to diagnose gonorrhoea, thus undermining our ability to detect antimicrobial resistance (AMR) using current technologies. In this Opinion article, we discuss the problem of N. gonorrhoeae AMR, particularly emerging resistance to the cephalosporin ceftriaxone, outline current concerns about the surveillance of N. gonorrhoeae AMR and propose the use of molecular methods on a large scale to systematically enhance surveillance.

Antimicrobial susceptibility/resistance and genetic characteristics of Neisseria gonorrhoeae isolates from Poland, 2010-2012

BACKGROUND

In Poland, gonorrhoea has been a mandatorily reported infection since 1948, however, the reported incidences are likely underestimated. No antimicrobial resistance (AMR) data for Neisseria gonorrhoeae has been internationally reported in nearly four decades, and data concerning genetic characteristics of N. gonorrhoeae are totally lacking. The aims of this study were to investigate the AMR to previously and currently recommended gonorrhoea treatment options, the main genetic resistance determinant (penA) for extended-spectrum cephalosporins (ESCs), and genotypic distribution of N. gonorrhoeae isolates in Poland in 2010-2012.

METHODS

N. gonorrhoeae isolates cultured in 2010 (n = 28), 2011 (n = 92) and 2012 (n = 108) in Warsaw and Bialystok, Poland, were examined using antimicrobial susceptibility testing (Etest), pyrosequencing of penA and N. gonorrhoeae multi-antigen sequence typing (NG-MAST).

RESULTS

The proportions of N. gonorrhoeae isolates showing resistance were as follows: ciprofloxacin 61%, tetracycline 43%, penicillin G 22%, and azithromycin 8.8%. No isolates resistant to ceftriaxone, cefixime or spectinomycin were found. However, the proportion of isolates with an ESC MIC = 0.125 mg/L, i.e. at the resistance breakpoint, increased significantly from none in 2010 to 9.3% and 19% in 2012 for ceftriaxone and cefixime, respectively. Furthermore, 3.1% of the isolates showed multidrug resistance, i.e., resistance to ciprofloxacin, penicillin G, azithromycin, and decreased susceptibility to cefixime (MIC = 0.125 mg/L). Seventy-six isolates (33%) possessed a penA mosaic allele and 14 isolates (6.1%) contained an A501V/T alteration in penicillin-binding protein 2. NG-MAST ST1407 (n = 58, 25% of isolates) was the most prevalent ST, which significantly increased from 2010 (n = 0) to 2012 (n = 46; 43%).

CONCLUSIONS

In Poland, the diversified gonococcal population displayed a high resistance to most antimicrobials internationally previously recommended for gonorrhoea treatment and decreasing susceptibility to the currently recommended ESCs. The decreasing susceptibility to ESCs was mostly due to the introduction of the internationally spread multidrug-resistant NG-MAST ST1407 in 2011. It is essential to promptly revise the gonorrhoea treatment guidelines, improve the gonorrhoea laboratory diagnostics, and implement quality assured surveillance of gonococcal AMR (ideally also treatment failures) in Poland.

Worldwide susceptibility rates of Neisseria gonorrhoeae isolates to cefixime and cefpodoxime: a systematic review and meta-analysis

BACKGROUND

Neisseria gonorrhoeae (NG) infection is a serious public health problem. The third-generation extended-spectrum cephalosporins (ESCs) have been used as the first-line treatment for NG infection for almost three decades. However, in recent years, treatment failures with the oral third-generation ESCs have been reported worldwide. This study aimed to estimate worldwide susceptibility rates of NG to cefixime and cefpodoxime by analyzing data from all relevant published studies.

METHODOLOGY/PRINCIPAL FINDINGS

Two researchers independently searched five databases to identify studies on susceptibilities of NG to cefixime and cefpodoxime published between January 1, 1984 and October 15, 2012. A fixed-effect model was used to perform group analysis, and a χ2 test was employed to make subgroup comparison. Publication bias was assessed with the Begg rank correlation test. The pooled susceptibility rate of NG isolates to cefixime was 99.8% (95% CI: 99.7%-99.8%). The cefixime susceptibility rate of NG isolates from men was significantly lower than that from patients without information of gender or from men and women; the susceptibility rate of NG isolates from Asia was significantly lower than that from other continents; and the susceptibility rate of NG isolates collected before or during 2003 was significantly higher than that after 2003. The pooled susceptibility rate of NG isolates to cefpodoxime was 92.8% (95% CI: 89.0%-95.3%), which was lower than that to cefixime (92.8% vs. 99.8%, χ2 = 951.809, P<0.01).

CONCLUSIONS

The susceptibility rate of NG isolates to cefixime varied with the gender of patients and geographical location from which NG isolates were collected, and declined with time. The reported lower susceptibility rate of NG isolates to cefixime and associated treatment failures, as well as the emergence of NG strains with cephalosporin resistance call for the more effective control of NG infection and the development of new antibiotics.

Gonorrhoea and gonococcal antimicrobial resistance surveillance networks in the WHO European Region, including the independent countries of the former Soviet Union

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae has emerged for essentially all antimicrobials following their introduction into clinical practice. During the latest decade, susceptibility to the last remaining options for antimicrobial monotherapy, the extended-spectrum cephalosporins (ESC), has markedly decreased internationally and treatment failures with these ESCs have been verified. In response to this developing situation, WHO and the European Centre for Disease Prevention and Control (ECDC) have published global and region-specific response plans, respectively. One main component of these action/response plans is to enhance the surveillance of AMR and treatment failures. This paper describes the perspectives from the diverse WHO European Region (53 countries), including the independent countries of the former Soviet Union, regarding gonococcal AMR surveillance networks. The WHO European Region has a high prevalence of resistance to all previously recommended antimicrobials, and most of the first strictly verified treatment failures with cefixime and ceftriaxone were also reported from Europe. In the European Union/European Economic Area (EU/EEA), the European gonococcal antimicrobial surveillance programme (Euro-GASP) funded by the ECDC is running. In 2011, the Euro-GASP included 21/31 (68%) EU/EEA countries, and the programme is further strengthened annually. However, in the non-EU/EEA countries, internationally reported and quality assured gonococcal AMR data are lacking in 87% of the countries and, worryingly, appropriate support for establishment of a GASP is still lacking. Accordingly, national and international support, including political and financial commitment, for gonococcal AMR surveillance in the non-EU/EEA countries of the WHO European Region is essential.

The role of core groups in the emergence and dissemination of antimicrobial-resistant N gonorrhoeae

Core groups contain individuals who are regularly infected with Neisseria gonorrhoeae and are able to transmit their infection to a large number of sexual partners. Classical core groups, such as sex workers and their male partners, or men who have sex with men (MSM), have contributed to the emergence and spread of antimicrobial-resistant N gonorrhoeae over many years. Sex workers and their clients were the most important core group driving the dissemination of penicillinase-producing N gonorrhoeae in the 1970s. Such individuals have continued to contribute to penicillinase-producing N gonorrhoeae outbreaks as well as to the subsequent emergence of gonococcal resistance to fluoroquinolones, macrolides, spectinomycin and cephalosporins in various settings. MSM have been a very important core group since the 1980s, first with the spread of TetM-expressing N gonorrhoeae and, second, with the dissemination of fluoroquinolone-resistant N gonorrhoeae. MSM-associated sexual networks have most recently been critical to the spread of gonococci resistant to third generation extended spectrum cephalosporins, including cefixime and ceftriaxone. Individuals within other core groups have also been linked to the transmission of antimicrobial-resistant gonorrhoea, such as military personnel, travellers, drug users, young adults, older men and members of street gangs. Understanding core behaviours and their geospatial clustering is essential for an optimal public health response to the rising prevalence of antimicrobial-resistant gonorrhoea. Furthermore, rapid and effective treatment of N gonorrhoeae infections in core individuals and their sexual partners should be a priority for gonorrhoea control programmes.

Gonococcal antimicrobial resistance in the Western Pacific Region

OBJECTIVE

To outline the current situation of gonococcal antimicrobial resistance (AMR) in the Western Pacific region and factors that impact on this.

BACKGROUND

The Western Pacific region is densely populated with many living in poverty. There are high rates of infectious diseases, and a disproportionate burden of gonococcal disease. In many countries there is uncontrolled antimicrobial use: these are ideal conditions for the emergence of AMR.

METHODS

Gonococcal AMR in this region has been monitored for more than 20 years. Clinical isolates, predominantly from unselected patients attending sexually transmitted diseases clinics, are tested against a panel of antibiotics. Quality assurance and control strategies are in place.

RESULTS

There is widespread, high level resistance to penicillin and ciprofloxacin. Decreased susceptibility to ceftriaxone (MIC ≥ 0.06 mg/L) is reported in high levels from some countries in the region. Low numbers of isolates tested in some countries reflect capacity for testing, and are suboptimal for surveillance.

CONCLUSION

The raised MIC values to ceftriaxone, and the emergence and spread of ceftriaxone resistant strains regionally is alarming. Sustaining and enhancing surveillance is critical; however obtaining an adequate sample size is a long-standing issue. The implementation of molecular surveillance strategies could provide broader information on the spread and threat of AMR.

Decreased susceptibility of Neisseria gonorrhoeae isolates from Switzerland to Cefixime and Ceftriaxone: antimicrobial susceptibility data from 1990 and 2000 to 2012

Background

Neisseria gonorrhoeae can rapidly develop resistance to antimicrobial agents. Over the last years, decreased gonococcal susceptibility to third-generation cephalosporins, especially cefixime, emerged worldwide. Therefore, current international guidelines recommend dual therapy for gonorrhoea with ceftriaxone plus either azithromycin or doxycycline. Gonococcal susceptibility data in Switzerland are sparse.

Methods

We investigated the prevalence of antibiotic susceptibility of N. gonorrhoeae in specimens collected between 1990 and 2012 at the University of Zurich, Switzerland. Minimum inhibitory concentrations (MICs) for cefixime, ceftriaxone, ciprofloxacin, and penicillin were determined by Etests. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used to define reduced susceptibility.

Results

A total of 320 isolates were tested. Between 1990 and 2006 all tested samples were susceptible to both cephalosporins. Subsequently, the prevalence of elevated MICs for cefixime increased to 10.4% (2007/2008), 11.5% (2009/2010), and 11.4% (2011/2012); and for ceftriaxone to 2.4% (2007/2008), 4.7% (2009/2010), and 0% (2011/2012), respectively. The prevalence of resistance to ciprofloxacin (72.7%) and penicillin (22.7%) was high in 2011/2012.

Conclusions

Decreasing susceptibility of N. gonorrhoeae to third-generation cephalosporins in Switzerland supports treatment recommendations with ceftriaxone plus azithromycin or doxycycline. Health-care providers need to be aware of possible treatment failures with cephalosporins. Continued surveillance of gonococcal antimicrobial resistance is essential.

Neisseria gonorrhoeae and extended-spectrum cephalosporins in California: surveillance and molecular detection of mosaic penA

BACKGROUND

The spread of Neisseria gonorrhoeae strains with mosaic penA alleles and reduced susceptibility to extended-spectrum cephalosporins is a major public health problem. While much work has been performed internationally, little is known about the genetics or molecular epidemiology of N. gonorrhoeae isolates with reduced susceptibility to extended-spectrum cephalosporins in the United States. The majority of N. gonorrhoeae infections are diagnosed without a live culture. Molecular tools capable of detecting markers of extended-spectrum cephalosporin resistance are needed.

METHODS

Urethral N. gonorrhoeae isolates were collected from 684 men at public health clinics in California in 2011. Minimum inhibitory concentrations (MICs) to ceftriaxone, cefixime, cefpodoxime and azithromycin were determined by Etest and categorized according to the U.S. Centers for Disease Control 2010 alert value breakpoints. 684 isolates were screened for mosaic penA alleles using real-time PCR (RTPCR) and 59 reactive isolates were subjected to DNA sequencing of their penA alleles and Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST). To increase the specificity of the screening RTPCR in detecting isolates with alert value extended-spectrum cephalosporin MICs, the primers were modified to selectively amplify the mosaic XXXIV penA allele.

RESULTS

Three mosaic penA alleles were detected including two previously described alleles (XXXIV, XXXVIII) and one novel allele (LA-A). Of the 29 isolates with an alert value extended-spectrum cephalosporin MIC, all possessed the mosaic XXXIV penA allele and 18 were sequence type 1407, an internationally successful strain associated with multi-drug resistance. The modified RTPCR detected the mosaic XXXIV penA allele in urethral isolates and urine specimens and displayed no amplification of the other penA alleles detected in this study.

CONCLUSION

N. gonorrhoeae isolates with mosaic penA alleles and reduced susceptibility to extended-spectrum cephalosporins are currently circulating in California. Isolates with the same NG-MAST ST, penA allele and extended-spectrum cephalosporin MICs have caused treatment failures elsewhere. The RTPCR assay presented here may be useful for the detection of N. gonorrheoae isolates and clinical specimens with reduced extended-spectrum cephalosporin MICs in settings where antimicrobial susceptibility testing is unavailable. In an era of increasing antimicrobial resistance and decreasing culture capacity, molecular assays capable of detecting extended-spectrum cephalosporin of resistance are essential to public health.

Characteristics of males infected with common Neisseria gonorrhoeae sequence types in the Gonococcal Isolate Surveillance Project, San Francisco, California, 2009

We analyzed 265 urethral Neisseria gonorrhoeae specimens collected from symptomatic males at San Francisco's municipal sexually transmitted disease clinic, a participant in the Gonococcal Isolate Surveillance Project, during 2009. We used N. gonorrhoeae multiantigen sequence typing to describe characteristics of patients infected with common sequence type families. Specimens were classified into 6 homology-based families and 1 additional family of all other identified strains. Strain family results were combined with results of culture-based antibiotic sensitivity minimum inhibitory concentration, sociodemographic and behavioral risk data collected at the clinic, and presence or absence of the mosaic penicillin-binding protein 2 (penA) allele. Characteristics of patients were compared across strain families through the use of χ(2) statistics. Among men who have sex with men, strain distribution differed by those reporting receptive oral sex as their only urethral exposure (P = 0.04), by number of sex partners (P = 0.03), and by race/ethnicity (P < 0.001); there were no differences by age or human immunodeficiency virus status. Also, among men who have sex with men, strain family distributions differed for culture specimens with reduced susceptibility to a range of antibiotics, as well as with presence of the mosaic penA allele (all P < 0.001). The combination of molecular, phenotypic, and epidemiologic data on N. gonorrhoeae infection could help develop a more complete epidemiology of gonorrhea in the United States.

Utility of specimens positive for Neisseria gonorrhoeae by the Aptima Combo 2 assay for assessment of strain diversity and antibiotic resistance

In our jurisdiction, the Aptima Combo 2 assay (Gen-Probe, Inc.) is used to detect Neisseria gonorrhoeae from specimens collected at clinics for sexually transmitted infections (STI) and from select community patients. In addition, swabs are also collected for N. gonorrhoeae culture, susceptibility testing, and sequence typing (ST). Since only a small proportion of samples from provincial cases undergo culture, the available trends in antimicrobial susceptibility and predominant strain types may not be representative of all N. gonorrhoeae infections. Due to the limitations facing the use of N. gonorrhoeae culture to understand these trends in the general community, we performed a molecular analysis for markers of cephalosporin resistance and ST determination by using nucleic acid extracts of specimens sent for Aptima testing. Thirty-four samples submitted for both Aptima testing and N. gonorrhoeae culture from the same anatomic location (within 24 h) were included in the study. Sequence type was determined based on the sequence of the por and tbpB genes, and amino acid changes in the PBP 2 protein, encoded by the penA gene, were considered representative for the assessment of antimicrobial susceptibility. Sequence identity of 100% was observed between the sequences obtained from Aptima-analyzed samples and culture samples. Sequencing results showed an association between decreased susceptibility to extended-spectrum cephalosporins (ESC(ds)), tbp allele 110, ST 1407, and amino acid changes (G545S, I312M, and V316T) in the PBP 2 protein. Our data, generated based on a few representative genes, suggest that gonococcal samples positive by Aptima testing can be used to determine single nucleotide polymorphisms associated with ESC(ds) and the sequence type based on molecular strain typing. Confirmation of these findings may obviate the need for gonorrhea culture in the future.

Antimicrobial resistance and molecular typing of Neisseria gonorrhoeae isolates in Kyoto and Osaka, Japan, 2010 to 2012: intensified surveillance after identification of the first strain (H041) with high-level ceftriaxone resistance

In 2009, the first high-level ceftriaxone-resistant Neisseria gonorrhoeae strain (H041) was isolated in Kyoto, Japan. The present study describes an intensified surveillance (antimicrobial resistance and molecular typing) of Neisseria gonorrhoeae isolates in Kyoto and its neighboring prefecture Osaka, Japan, in 2010 to 2012, which was initiated after the identification of H041. From April 2010 to March 2012, 193 N. gonorrhoeae isolates were collected and the MICs (μg/ml) to six antimicrobials, including ceftriaxone, were determined. All isolates showed susceptibility to ceftriaxone and cefixime (MIC values, <0.5 μg/ml), and spectinomycin. The rates of resistance (intermediate susceptibility) to azithromycin, penicillin G, and ciprofloxacin were 3.6% (19.7%), 24.4% (71.0%), and 78.2% (0.5%), respectively. Multilocus sequence typing (MLST) showed that 40.9%, 19.2%, and 17.1% of isolates belonged to ST1901, ST7359, and ST7363, respectively. Furthermore, N. gonorrhoeae multiantigen sequence typing (NG-MAST) revealed that 12 (63%) of the 19 isolates with decreased susceptibility to ceftriaxone (MIC > 0.064 μg/ml) were of ST1407. NG-MAST ST1407 was also the most prevalent ST (16.1%; 31 of 193 isolates). In those NG-MAST ST1407 strains, several mosaic type penA alleles were found, including SF-A type (penicillin binding protein 2 allele XXXIV) and its derivatives. These were confirmed using transformation of the penA mosaic alleles as critical determinants for enhanced cefixime and ceftriaxone MICs. The intensified surveillance in Kyoto and Osaka, Japan, did not identify any dissemination of the high-level ceftriaxone-resistant N. gonorrhoeae strain H041, suggesting that H041 might have caused only a sporadic case and has not spread further.

Does the ‘2012 IUSTI ECCG report on the diagnosis and management of Neisseria gonorrhoeae infections in Europe’ depict the situation in Europe?

Summary

Gonorrhoea is a major public health concern globally. Of particular grave concern is that resistance to the third generation cephalosporins has been identified during recent years. This paper summarises and discusses the results of the ‘2012 IUSTI European Collaborative Clinical Group (ECCG) report on the diagnosis and management of Neisseria gonorrhoeae infections in Europe’. Although high quality care was reported in many settings, in several other countries the testing, diagnostics, antimicrobial treatment and follow-up of gonorrhoea patients need to be optimized. This, together with increased access to and use of antimicrobial susceptibility testing, is crucial in controlling the emergent spread of cephalosporin-resistant and multidrug-resistant gonorrhoea.

Pilot study to introduce a notification card for partner notification of sexually transmitted infections in Catalonia, Spain, June 2010 to June 2011

We conducted a cross-sectional study in 10 primary care centres in Catalonia, to determine applicability, acceptability and effectiveness of partner notification cards used by patients diagnosed of a sexually transmitted infection (STI) and to characterise these and their sexual partners. Statutorily notifiable STIs included Chlamydia infection, gonorrhoea, syphilis, human immunodeficiency virus (HIV) infection or other STIs as deemed necessary by the treating physician. Between June 2010 and June 2011, 219 index cases were enrolled, of whom 130 were men (59.4%), 71 of them men who have sex with men (54.6%). Chlamydia infection (41.1%), gonorrhoea (17.8%) and syphilis (16.0%) were the STIs most frequently diagnosed. HIV infection accounted for 4% of cases. A total of 687 sexual partners were reported, and 300 of these were traceable through the notification card (45.7%). Those who did not report traceable contacts were older (mean age: 34 years versus 31 years, p=0.03). The main reason for not distributing the card was anonymous sexual intercourse (38%). Patient referral notification cards can reach a high percentage of sexual partners at risk. However, only few notified sexual partners attended participating health centres. Internet-based partner notification may be considered in order to reach those partners not otherwise traceable.

Phenotypic and genetic characterization of the first two cases of extended-spectrum-cephalosporin-resistant Neisseria gonorrhoeae infection in South Africa and association with cefixime treatment failure

OBJECTIVES

To describe the phenotypic and genetic characteristics of the first two cases of extended-spectrum cephalosporin (ESC)-resistant Neisseria gonorrhoeae in South Africa, one of which was associated with verified cefixime treatment failure.

PATIENTS AND METHODS

Two ESC-resistant N. gonorrhoeae isolates were cultured from the urethral discharge of two men who have sex with men (MSM). One man reported a persistent urethral discharge that had failed to respond to previous therapy with oral cefixime. Agar dilution MICs were determined for eight antibiotics. β-Lactam-associated resistance mutations were identified through PCR-based amplification and sequencing for several key genes: penA, mtrR and its promoter, porB1b (penB), ponA and pilQ. For molecular epidemiological characterization, full-length porB gene sequencing, N. gonorrhoeae multiantigen sequence typing (NG-MAST) and multilocus sequence typing (MLST) were performed.

RESULTS

Both isolates were resistant to cefixime, ciprofloxacin, penicillin and tetracycline and intermediate/resistant to azithromycin, but susceptible to ceftriaxone, gentamicin and spectinomycin. Both isolates had the type XXXIV penA mosaic allele in addition to previously described resistance mutations in the mtrR promoter (A deletion), porB1b (penB) (G101K and A102N) and ponA1 (L421P). Both isolates had an identical NG-MAST sequence type (ST4822) and MLST sequence type (ST1901).

CONCLUSIONS

Both isolates were resistant to cefixime and possessed a number of identical mutations in key genes contributing to ESC resistance in N. gonorrhoeae. The two isolates contained the type XXXIV penA mosaic allele and belonged to a successful international MSM-linked multidrug-resistant gonococcal clone (MLST ST1901) associated with several cefixime treatment failures in Europe and North America.

Identification of amino acids conferring high-level resistance to expanded-spectrum cephalosporins in the penA gene from Neisseria gonorrhoeae strain H041

The recent identification of a high-level-ceftriaxone-resistant (MIC = 2 to 4 μg/ml) isolate of Neisseria gonorrhoeae from Japan (H041) portends the loss of ceftriaxone as an effective treatment for gonococcal infections. This is of grave concern because ceftriaxone is the last remaining option for first-line empirical antimicrobial monotherapy. The penA gene from H041 (penA41) is a mosaic penA allele similar to mosaic alleles conferring intermediate-level cephalosporin resistance (Ceph(i)) worldwide but has 13 additional mutations compared to the mosaic penA gene from the previously studied Ceph(i) strain 35/02 (penA35). When transformed into the wild-type strain FA19, the penA41 allele confers 300- and 570-fold increases in the MICs for ceftriaxone and cefixime, respectively. In order to understand the mechanisms involved in high-level ceftriaxone resistance and to improve surveillance and epidemiology during the potential emergence of ceftriaxone resistance, we sought to identify the minimum number of amino acid alterations above those in penA35 that confer high-level resistance to ceftriaxone. Using restriction fragment exchange and site-directed mutagenesis, we identified three mutations, A311V, T316P, and T483S, that, when incorporated into the mosaic penA35 allele, confer essentially all of the increased resistance of penA41. A311V and T316P are close to the active-site nucleophile Ser310 that forms the acyl-enzyme complex, while Thr483 is predicted to interact with the carboxylate of the β-lactam antibiotic. These three mutations have thus far been described only for penA41, but dissemination of these mutations in other mosaic alleles would spell the end of ceftriaxone as an effective treatment for gonococcal infections.

Polymerase chain reaction-based screening for the ceftriaxone-resistant Neisseria gonorrhoeae F89 strain

Emergence and spread of Neisseria gonorrhoeae resistant to extended spectrum cephalosporins is a major problem threatening treatment of gonorrhoea and is further highlighted by the recent report of a second ceftriaxone-resistant N. gonorrhoeae strain (F89) in Europe, initially observed in France and subsequently identified in Spain. N. gonorrhoeae antimicrobial resistance (AMR) surveillance has acquired new importance and molecular tools have the potential to enhance bacterial culture-based methods. In this study, we established a polymerase chain reaction (PCR) protocol for direct detection of the F89 strain. A key component of this screening protocol was the development of a hybridisation probe-based melting curve analysis assay (mosaic501-hybPCR) to detect the presence of an A501P substitution on the N. gonorrhoeae mosaic penicillin binding protein 2 (PBP2) sequence, an important characteristic of the F89 strain. The mosaic501-hybPCR was evaluated using plasmid-derived positive controls (n=3) and characterised gonococcal (n=33) and non-gonococcal (n=58) isolates. The protocol was then applied to 159 clinical specimens from Sydney, Australia, collected during the first half of the year 2012 that were N. gonorrhoeae PCR-positive. Overall, the results indicate that the PCR-based protocol is suitable for direct detection of the N. gonorrhoeae F89 strain in non-cultured clinical samples. It therefore provides an additional tool to aid investigations into the potential spread of F89 strain throughout Europe and elsewhere.

Antimicrobial susceptibility and genetic characteristics of Neisseria gonorrhoeae isolates from Vietnam, 2011

BACKGROUND

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a major public health concern worldwide. In Vietnam, knowledge regarding N. gonorrhoeae prevalence and AMR is limited, and data concerning genetic characteristics of N. gonorrhoeae is totally lacking. Herein, we investigated the phenotypic AMR (previous, current and possible future treatment options), genetic resistance determinants for extended-spectrum cephalosporins (ESCs), and genotypic distribution of N. gonorrhoeae isolated in 2011 in Hanoi, Vietnam.

METHODS

N. gonorrhoeae isolates from Hanoi, Vietnam isolated in 2011 (n = 108) were examined using antibiograms (Etest for 10 antimicrobials), Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST), and sequencing of ESC resistance determinants (penA, mtrR and penB).

RESULTS

The levels of in vitro resistance were as follows: ciprofloxacin 98%, tetracycline 82%, penicillin G 48%, azithromycin 11%, ceftriaxone 5%, cefixime 1%, and spectinomycin 0%. The MICs of gentamicin (0.023-6 mg/L), ertapenem (0.002-0.125 mg/L) and solithromycin (<0.016-0.25 mg/L) were relatively low. No penA mosaic alleles were found, however, 78% of the isolates contained an alteration of amino acid A501 (A501V (44%) and A501T (34%)) in the encoded penicillin-binding protein 2. A single nucleotide (A) deletion in the inverted repeat of the promoter region of the mtrR gene and amino acid alterations in MtrR was observed in 91% and 94% of the isolates, respectively. penB resistance determinants were detected in 87% of the isolates. Seventy-five different NG-MAST STs were identified, of which 59 STs have not been previously described.

CONCLUSIONS

In Vietnam, the highly diversified gonococcal population displayed high in vitro resistance to antimicrobials previously recommended for gonorrhoea treatment (with exception of spectinomycin), but resistance also to the currently recommended ESCs were found. Nevertheless, the MICs of three potential future treatment options were low. It is essential to strengthen the diagnostics, case reporting, and epidemiologic surveillance of gonorrhoea in Vietnam. Furthermore, the surveillance of gonococcal AMR and gonorrhoea treatment failures is imperative to reinforce. Research regarding novel antimicrobial treatment strategies (e.g., combination therapy) and new antimicrobials is crucial for future treatment of gonorrhoea.

Antimicrobial susceptibility and genetic characteristics of Neisseria gonorrhoeae isolates from India, Pakistan and Bhutan in 2007-2011

BACKGROUND

Knowledge on antimicrobial drug resistance and genetic characteristics of Neisseria gonorrhoeae isolates circulating in India, Pakistan, and Bhutan is sorely lacking. In this paper, we describe the prevalence of antimicrobial resistance and molecular characteristics of N. gonorrhoeae isolates from India, Pakistan, and Bhutan in 2007-2011.

METHODS

Antimicrobial susceptibility and β-lactamase production were tested for 65 N. gonorrhoeae isolates from India (n=40), Pakistan (n=18) and Bhutan (n=7) using Etest methodology (eight antimicrobials) and nitrocefin solution, respectively. Resistance determinants, i.e. penA, mtrR, porB1b, gyrA, and parC, were sequenced. N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed for molecular epidemiology.

RESULTS

The highest resistance level was observed for ciprofloxacin (94%), followed by penicillin G (68%), erythromycin (62%), tetracycline (55%), and azithromycin (7.7%). All the isolates were susceptible to ceftriaxone, cefixime, and spectinomycin. Thirty-four (52%) of the isolates were producing β-lactamase. No penA mosaic alleles or A501-altered alleles of penicillin-binding protein 2 were identified. Forty-nine NG-MAST STs were identified, of which 42 STs have not been previously described worldwide.

CONCLUSIONS

Based on this study, ceftriaxone, cefixime, and spectinomycin can be used as an empirical first-line therapy for gonorrhoea in India, Pakistan, and Bhutan, whereas ciprofloxacin, penicillin G, tetracycline, erythromycin, and azithromycin should not be. It is imperative to strengthen the laboratory infrastructure in this region, as well as to expand the phenotypic and genetic surveillance of antimicrobial resistance, emergence of new resistance, particularly, to extended-spectrum cephalosporins, and molecular epidemiology.

Emergence of multidrug-resistant, extensively drug-resistant and untreatable gonorrhea

The new superbug Neisseria gonorrhoeae has retained resistance to antimicrobials previously recommended for first-line treatment and has now demonstrated its capacity to develop resistance to the extended-spectrum cephalosporin, ceftriaxone, the last remaining option for first-line empiric treatment of gonorrhea. An era of untreatable gonorrhea may be approaching, which represents an exceedingly serious public health problem. Herein, we review the evolution, origin and spread of antimicrobial resistance and resistance determinants (with a focus on extended-spectrum cephalosporins) in N. gonorrhoeae, detail the current situation regarding verified treatment failures with extended-spectrum cephalosporins and future treatment options, and highlight essential actions to meet the large public health challenge that arises with the possible emergence of untreatable gonorrhea. Essential actions include: implementing action/response plans globally and nationally; enhancing surveillance of gonococcal antimicrobial resistance, treatment failures and antimicrobial use/misuse; and improving prevention, early diagnosis and treatment of gonorrhea. Novel treatment strategies, antimicrobials (or other compounds) and, ideally, a vaccine must be developed.

Neisseria gonorrhoeae strain with high-level resistance to spectinomycin due to a novel resistance mechanism (mutated ribosomal protein S5) verified in Norway

Gonorrhea may become untreatable, and new treatment options are essential. Verified resistance to spectinomycin is exceedingly rare. However, we describe a high-level spectinomycin-resistant (MIC, >1,024 μg/ml) Neisseria gonorrhoeae strain from Norway with a novel resistance mechanism. The resistance determinant was a deletion of codon 27 (valine) and a K28E alteration in the ribosomal protein 5S. The traditional spectinomycin resistance gene (16S rRNA) was wild type. Despite this exceedingly rare finding, spectinomycin available for treatment of ceftriaxone-resistant urogenital gonorrhea would be very valuable.