The use of cephalosporins for gonorrhea: the impending problem of resistance

Antimicrobial resistance to Neisseria gonorrhoeae in Canada: 2009-2013

Background

Gonorrhea is on the rise in Canada. Treatment has been complicated by the fact that Neisseria gonorrhoeae has acquired resistance to many antibiotics, including penicillin, tetracycline, erythromycin and ciprofloxacin. The emergence of isolates with decreased susceptibilities to the third generation cephalosporins and reports of treatment failures in Canada and around the world are cause for concern.

Objective

To assess the resistance levels of common antibiotics to N. gonorrhoeae and to observe trends in resistance and/or decreased susceptibility to ciprofloxacin, third generation cephalosporins and azithromycin.

Methods

Laboratory surveillance data for N. gonorrhoeae isolates submitted by provincial microbiology laboratories to the National Microbiology Laboratory (NML) from 2009-2013 were compared.

Results

Since 2009, there has been an overall rise in antibiotic-resistant N. gonorrhoeae. In 2013, 24.3% of the isolates were resistant to erythromycin, 18.9% were resistant to penicillin, 33.0% were resistant to tetracycline, and 29.3% were resistant to ciprofloxacin. The percentage of isolates with decreased susceptibility to ceftriaxone (≥0.125 mg/L) and/or cefixime (≥0.25 mg/L) was 3.9% in 2013. This number represents a decrease from 5.9% in 2012 and 7.6% in 2011. The proportion of azithromycin resistant (MIC ≥2 mg/L) N. gonorrhoeae isolates increased from 0.4% in 2009 to 1.2% in 2013.

Conclusion

Resistance to erythromycin, penicillin, tetracycline and ciprofloxacin is common. Decreased susceptibility to ceftriaxone and/or cefixime is now almost 4% and azithromycin resistance is emerging but remains low at 1.2%. These results have informed the gonococcal infection treatment recommendations in the Canadian Guidelines on Sexually Transmitted Infections.

In vitro assessment of dual drug combinations to inhibit growth of Neisseria gonorrhoeae

The development of resistance to first-line antimicrobial therapies has led to recommendations for combination therapies for the treatment of gonorrhea infection. Recent studies have shown the success of combination therapies in treating patients, but few have reported on the in vitro activities of these drug combinations. An in vitro assessment of azithromycin in combination with gentamicin demonstrated inhibition of growth and suggests that clinical trials may be warranted to assess the utility of this combination in treating gonorrhea infections.

Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from symptomatic men attending the Nanjing sexually transmitted diseases clinic (2011-2012): genetic characteristics of isolates with reduced sensitivity to ceftriaxone

BACKGROUND

Evolving gonococcal antimicrobial resistance (AMR) poses a serious threat to public health. The aim of this study was to: update antimicrobial susceptibility data of Neisseria gonorrhoeae recently isolated in Nanjing, China and identify specific deteminants of antimicrobial resistance and gentoypes of isolates with decreased sensitivity to ceftriaxone.

METHODS

334 N. gonorrhoeae isolates were collected consecutively from symptomatic men attending the Nanjing STD Clinic between April 2011 and December 2012. The minimum inhibitory concentrations (MICs) for penicillin, tetracycline, ciprofloxacin, spectinomycin and ceftriaxone were determined by agar plate dilution for each isolate. Penicillinase-producing N. gonorrhoeae (PPNG) and tetracycline-resistant N. gonorrhoeae (TRNG) were examined and typed for β-lactamase and tetM encoding plasmids respectively. Isolates that displayed elevated MICs to ceftriaxone (MIC ≥0.125 mg/L) were also tested for mutations in penA, mtrR, porB1b, ponA and pilQ genes and characterized by Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST).

RESULTS

98.8% (330/334) of N. gonorrhoeae isolates were resistant to ciprofloxacin; 97.9% (327/334) to tetracycline and 67.7% (226/334) to penicillin. All isolates were susceptible to ceftriaxone (MIC ≤0.25 mg/L) and spectinomycin (MIC ≤32 mg/L). Plasmid mediated resistance was exhibited by 175/334 (52%) of isolates: 120/334 (36%) of isolates were PPNG and 104/334 (31%) were TRNG. 90.0% (108/120) of PPNG isolates carried the Asia type β-lactamase encoding plasmid and 96% (100/104) of TRNG isolates carried the Dutch type tetM containing plasmid. Elevated MICs for ceftriaxone were present in 15 (4.5%) isolates; multiple mutations were found in penA, mtrR, porB1b and ponA genes. The 15 isolates were distributed into diverse NG-MAST sequence types; four different non-mosaic penA alleles were identified, including one new type.

CONCLUSIONS

N. gonorrhoeae isolates in Nanjing generally retained similar antimicrobial resistance patterns to isolates obtained five years ago. Fluctuations in resistance plasmid profiles imply that genetic exchange among gonococcal strains is ongoing and is frequent. Ceftriaxone and spectinomycin remain treatments of choice of gonorrhea in Nanjing, however, decreased susceptibility to ceftriaxone and rising MICs for spectinomycin of N. gonorrhoeae isolates underscore the importance of maintaining surveillance for AMR (both phenotypic and genotypic).

Is gonorrhea becoming untreatable?

An estimated 498 million new cases of curable sexually transmitted infections occur worldwide annually. Of these, 106 million are gonococcal infections, rendering gonorrhea the second most prevalent bacterial sexually transmitted infection after chlamydia. A decline in susceptibility to extended-spectrum cephalosporins, as well as treatment failures, have been identified worldwide. This, together with the associated epidemiological and socioeconomic burden, is of increasing concern. Currently, the effectiveness of antibiotic resistance control measures is limited. Barriers include the lack of therapeutic options, the difficulties of reducing high-risk sexual behavior and Neisseria gonorrhoeae's propensity to rapidly acquire resistance determinants. While the disease remains treatable for the moment, we need to anticipate and be prepared for the arrival and spread of untreatable gonorrhea by using a multifaceted approach and search for other, perhaps novel control strategies.

Whole-genome phylogenomic heterogeneity of Neisseria gonorrhoeae isolates with decreased cephalosporin susceptibility collected in Canada between 1989 and 2013

A large-scale, whole-genome comparison of Canadian Neisseria gonorrhoeae isolates with high-level cephalosporin MICs was used to demonstrate a genomic epidemiology approach to investigate strain relatedness and dynamics. Although current typing methods have been very successful in tracing short-chain transmission of gonorrheal disease, investigating the temporal evolutionary relationships and geographical dissemination of highly clonal lineages requires enhanced resolution only available through whole-genome sequencing (WGS). Phylogenomic cluster analysis grouped 169 Canadian strains into 12 distinct clades. While some N. gonorrhoeae multiantigen sequence types (NG-MAST) agreed with specific phylogenomic clades or subclades, other sequence types (ST) and closely related groups of ST were widely distributed among clades. Decreased susceptibility to extended-spectrum cephalosporins (ESC-DS) emerged among a group of diverse strains in Canada during the 1990s with a variety of nonmosaic penA alleles, followed in 2000/2001 with the penA mosaic X allele and then in 2007 with ST1407 strains with the penA mosaic XXXIV allele. Five genetically distinct ESC-DS lineages were associated with penA mosaic X, XXXV, and XXXIV alleles and nonmosaic XII and XIII alleles. ESC-DS with coresistance to azithromycin was observed in 5 strains with 23S rRNA C2599T or A2143G mutations. As the costs associated with WGS decline and analysis tools are streamlined, WGS can provide a more thorough understanding of strain dynamics, facilitate epidemiological studies to better resolve social networks, and improve surveillance to optimize treatment for gonorrheal infections.

Certain attributes of the sexual ecosystem of high-risk MSM have resulted in an altered microbiome with an enhanced propensity to generate and transmit antibiotic resistance

Surveillance data from a number of countries have indicated that antibiotic resistance in Neisseriagonorrhoea is strongly associated with men who have sex with men (MSM). This manuscript advances the hypothesis that certain features of the MSM sexual ecosystem may be responsible for this association. It is argued that in comparison with heterosexuals, high-risk MSM (hrMSM) have a higher prevalence of oro-penile, oro-rectal and anal sex which facilitates an enhanced mixing of the pharyngeal, rectal and penile microbiomes. In addition, hrMSM have an increased number of sexual partners per unit time and an increased prevalence of sexual relationships overlapping in time. The increased flux of microbiomes between different body habitats between sexual partners, in combination with the increased connectivity of the sexual network, serve to create a novel high-risk MSM sexual ecosystem with important consequences for the genesis and spread of antibiotic resistance.

Reference map and comparative proteomic analysis of Neisseria gonorrhoeae displaying high resistance against spectinomycin

A proteome reference map of Neisseria gonorrhoeae was successfully established using two-dimensional gel electrophoresis in conjunction with matrix-assisted laser desorption ionization-time of flight mass spectrometry. This map was further applied to compare protein expression profiles of high-level spectinomycin-resistant (clinical isolate) and -susceptible (reference strain) N. gonorrhoeae following treatment with subminimal inhibitory concentrations (subMICs) of spectinomycin. Approximately 200 protein spots were visualized by Coomassie brilliant blue G-250 staining and 66 spots representing 58 unique proteins were subsequently identified. Most of the identified proteins were analysed as cytoplasmic proteins and belonged to the class of energy metabolism. Comparative proteomic analysis of whole protein expression of susceptible and resistant gonococci showed up to 96% similarity while eight proteins were found to be differentially expressed in the resistant strain. In the presence of subMICs of spectinomycin, it was found that 50S ribosomal protein L7/L12, an essential component for ribosomal translocation, was upregulated in both strains, ranging from 1.5- to 3.5-fold, suggesting compensatory mechanisms of N. gonorrhoeae in response to antibiotic that inhibits protein synthesis. Moreover, the differential expression of proteins involved in energy metabolism, amino acid biosynthesis, and the cell envelope was noticeably detected, indicating significant cellular responses and adaptation against antibiotic stress. Such knowledge provides valuable data, not only fundamental proteomic data, but also knowledge of the mode of action of antibiotic and secondary target proteins implicated in adaptation and compensatory mechanisms.

Assessment of Etest as an alternative to agar dilution for antimicrobial susceptibility testing of Neisseria gonorrhoeae

We studied whether the Etest can be used as an alternative to agar dilution to determine antimicrobial susceptibilities of ceftriaxone, cefixime, and cefpodoxime in Neisseria gonorrhoeae surveillance. One hundred fifteen clinical and laboratory isolates of N. gonorrhoeae were tested following the Clinical Laboratory Improvement Amendments (CLIA)-approved CLSI standard agar dilution method and, separately, by the Etest according to the manufacturer's recommendations. The MICs were determined and compared. Ten laboratory-generated mutants were used to simulate substantially nonsusceptible specimens. The Etest and agar dilution methods were well correlated. Statistical tests produced regression R2 values of 88%, 82%, and 85% and Pearson correlation coefficients of 92%, 91%, and 92% for ceftriaxone, cefixime, and cefpodoxime, respectively. When paired comparisons were made, the two tests were 88.7%, 80%, and 87% within 1 log2 dilution from each other for ceftriaxone, cefixime, and cefpodoxime, respectively. The within-2-log2 agreements were 99.1%, 98.3%, and 94.8% for ceftriaxone, cefixime, and cefpodoxime, respectively. Notwithstanding the good correlations and the within-2-log2 general agreement, the Etest results produced slightly lower MICs than the agar dilution results. In conclusion, we found that the Etest can be effectively used as an alternative to agar dilution testing to determine the susceptibility of N. gonorrhoeae to ceftriaxone, cefixime, and cefpodoxime, although we recommend further research into extremely resistant isolates. For isolates within the typical range of clinical MICs, reexamination of the Etest interpretation of susceptible and nonsusceptible categories would likely allow for successful transition from agar dilution to the Etest.

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.

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.

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.

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 susceptibilities and distribution of sequence types of Neisseria gonorrhoeae isolates in Canada: 2010

The monitoring of antimicrobial susceptibilities in Neisseria gonorrhoeae isolates and characterization of N. gonorrhoeae multiantigen sequence types (NG-MAST, ST) provide important surveillance data as resistance rates continue to rise. A total of 2970 N. gonorrhoeae isolates were collected by Canadian provincial public health laboratories in 2010, and 1233 were submitted to the National Microbiology Laboratory for testing. The NG-MAST and minimum inhibitory concentration (MIC) by agar dilution were determined for each isolate. Of the 2970 isolates, 25.1% were resistant to penicillin, 34.6% resistant to tetracycline, 31.5% resistant to erythromycin, 35.9% resistant to ciprofloxacin, and 1.2% resistant to azithromycin. Decreased susceptibility to cefixime (MIC ≥ 0.25 mg/L) and ceftriaxone (MIC ≥ 0.125 mg/L) was identified in 3.2% and 7.3% of the isolates, respectively. The most common STs found in Canada were ST1407 (13.3%), ST3150 (11.3%), and ST3158 (9.0%), with 249 different STs identified among the isolates. Within the ST1407 group, 19.5% and 43.3% isolates have decreased susceptibility to cefixime and ceftriaxone, respectively. ST1407, the most prevalent NG-MAST in Canada in 2010, has been associated with high-level ceftriaxone MICs and with cefixime treatment failure cases worldwide. Identification and monitoring of STs and corresponding antimicrobial resistance profiles may be useful in surveillance programs and be used to inform public health actions.

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.

Cephalosporin and azithromycin susceptibility in Neisseria gonorrhoeae isolates by site of infection, British Columbia, 2006 to 2011

BACKGROUND

Widespread resistance of Neisseria gonorrhoeae to penicillin, tetracycline, and fluoroquinolones has challenged effective treatment and control; recent international case reports of cefixime, ceftriaxone, and azithromycin resistance suggest that the remaining treatment options are now additionally threatened. To explore trends in antimicrobial susceptibility of N. gonorrhoeae, we reviewed provincial laboratory data from British Columbia, 2006 to 2011.

METHODS

Susceptibility testing was performed for all N. gonorrhoeae isolates detected in-house or forwarded to the reference laboratory. Resistance or intermediate resistance (nonsusceptibility) was defined by standard breakpoints for penicillin, tetracycline, ciprofloxacin, and spectinomycin. Elevated minimum inhibitory concentrations (MICs) at serial dilutions of 0.064 μg/mL or greater were explored for cefixime/ceftriaxone and 0.5 μg/mL or greater for azithromycin. Nonsusceptibility/elevated MIC was compared by year, site of infection, sex, and age.

RESULTS

A total of 1837 isolates representing 22% of all reported gonorrhea cases were analyzed. Nonsusceptibility to penicillin was established at baseline. Nonsusceptibility to tetracycline and ciprofloxacin increased over the study period, reaching 96% and 36%, respectively, in 2011. Sixteen isolates (1%) had a cefixime MIC of 0.25 μg/mL (none ≥0.5), none had a ceftriaxone MIC of 0.25 μg/mL or greater, and 15 (1%) had an azithromycin MIC of 2.0 μg/mL or greater. Elevated MIC of these agents showed an increasing trend over time. Nonsusceptibility and elevated MIC were consistently highest at the rectal and pharyngeal sites and higher in isolates from males, including when stratified to the pharyngeal site.

INTERPRETATION

Increases in elevated MIC of cefixime/ceftriaxone/azithromycin were superimposed on a background of established resistance to penicillin, tetracycline, and ciprofloxacin and may signal impending gonococcal resistance to first-line treatments. Ongoing surveillance will inform timely shifts in treatment recommendations.

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.

Trends in antimicrobial resistance in Neisseria gonorrhoeae isolated in Canada: 2000-2009

BACKGROUND

Canada conducts surveillance of penicillin, tetracycline, erythromycin, spectinomycin, ciprofloxacin, cefixime, and ceftriaxone susceptibilities in Neisseria gonorrhoeae isolates to support development of national treatment guidelines for sexually transmitted infections.

METHODS

N. gonorrhoeae isolates were collected by Canadian provincial public health laboratories and included isolates from males and females ranging in age from 1 to 86 years. Minimum inhibitory concentrations (MICs) were determined by agar dilution at the National Microbiology Laboratory, Public Health Agency of Canada, and MIC interpretations were based on the criteria of the Clinical Laboratory Standards Institute.

RESULTS

From 2000 to 2009, 40,875 isolates of N. gonorrhoeae were tested by provincial laboratories and 10,993 of these were characterized by the Public Health Agency of Canada. There was an increasing incidence of N. gonorrhoeae isolates that were chromosomally resistant to penicillin, tetracycline, and erythromycin while the plasmid-mediated resistance strains (penicillinase-producing N. gonorrhoeae, tetracycline-resistant N. gonorrhoeae, and PP/tetracycline-resistant N. gonorrhoeae strain all had a declining trend. The percentage of isolates resistant to ciprofloxacin significantly increased from 1.3% in 2000 to 25.5% in 2009. Only 0.17% of isolates tested were azithromycin resistant. Between 2000 and 2009, the modal MICs for ceftriaxone increased from 0.016 μg/mL to 0.063 μg/mL.

CONCLUSIONS

Ciprofloxacin resistance in N. gonorrhoeae within Canada has increased to a level where quinolones are no longer the preferred drugs for the treatment of gonococcal infections and the modal MICs for the third-generation cephalosporins have increased over time. Close monitoring of antibiotic susceptibilities are required to inform treatment options.

Point-of-care testing improves accuracy of STI care in an emergency department

OBJECTIVES

We aimed to examine the impact of a point-of-care (POC) test on overtreatment and undertreatment of sexually transmitted infections (STIs) by comparing treatment patterns for gonorrhoea (detected with nucleic acid amplification testing (NAAT)) with trichomoniasis (detected by POC test) for young women seen in an emergency department (ED).

METHODS

We reviewed the database of a quality improvement (QI) project that aims to improve follow-up care for STIs in the ED. Data included the test result and antibiotic given (if any) during visits by women age 14-21 for whom an STI test was ordered. We generated Shewhart control charts and compared overtreatment and undertreatment rates for gonorrhoea and trichomoniasis using χ(2) testing.

RESULTS

Of 1877 visits over 18 months, 8.8% of women had gonorrhoea and 16.5% had trichomoniasis. Overtreatment was higher for women with gonorrhoea than trichomoniasis (54% vs 23%, p<0.001). Overtreatment for gonorrhoea decreased from 58% to 47% (p<0.01) and overtreatment for trichomoniasis decreased from 24% to 18% (p<0.01), which corresponded to improvements in patient follow-up for the QI project. Undertreatment was higher for women with gonorrhoea than trichomoniasis (29% vs 21%, p=0.03), and did not change over time.

CONCLUSIONS

A POC test improves the accuracy of STI care in an ED compared with NAAT testing. An unanticipated benefit of QI efforts to improve patient follow-up is the observed decrease in antibiotic use in the ED. Given the ability of gonorrhoea to develop antibiotic resistance, future efforts should focus on development of an accurate POC test for gonorrhoea.

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.

Retrospective analysis of antimicrobial susceptibility trends (2000-2009) in Neisseria gonorrhoeae isolates from countries in Latin America and the Caribbean shows evolving resistance to ciprofloxacin, azithromycin and decreased susceptibility to ceftriaxone

BACKGROUND

The emergence of resistance and treatment failures to third generation cephalosporins prompted the revitalization of the global Gonococcal Antimicrobial Surveillance Program (GASP) to ensure that information regarding trends of the antimicrobial susceptibility of Neisseria gonorrhoeae isolates is up-to-date. Accordingly, former and potential GASP participants in Latin America and the Caribbean were contacted to reinitiate the GASP network in the region and to undertake a retrospective analysis of the antimicrobial susceptibility of N. gonorrhoeae isolates between 2000 and 2009.

METHODS

Eleven countries participated in this retrospective analysis reporting on the susceptibility of N. gonorrhoeae isolates to up to 6 antibiotics as well as national treatment guidelines over the period. Antimicrobial susceptibility determination was carried out using combination of agar dilution and disk diffusion (Clinical Laboratory and Standards Institute) or Etest. Antimicrobial susceptibility data from each country were aggregated and analyzed for antimicrobial resistance trends in the region.

RESULTS

More than 11,400 N. gonorrhoeae isolates were tested for antimicrobial susceptibility: 6 countries tested N. gonorrhoeae over the entire period and 5 countries tested sporadically. Decreased susceptibility to ceftriaxone was reported from 1 country (7 isolates, MICs >0.25 μg/ml) in 2007. No resistance to spectinomycin was reported. From 2000 to 2009, aggregated ciprofloxacin resistance increased from 2% (19/784) to 31% (311/1015) in 9 countries and azithromycin resistance increased from 6% (39/646) to 23% (225/962) in 4/6 reporting countries. Overall, resistance to penicillin and tetracycline decreased from 35% (441/1241) to 26% (258/975) and from 60% (476/792) to 35% (323/931), respectively.In 2009, resistance to gentamicin (3%, 4/122), chloramphenicol (5%, 6/120), and ofloxacin (2%, 6/120) was reported from 1 country.

CONCLUSIONS

The report of ceftriaxone-resistant isolates coupled with the emergence and spread of resistance to ciprofloxacin and azithromycin in Latin America and the Caribbean in the 2000s indicates the importance of active surveillance of N. gonorrhoeae antimicrobial susceptibility to determine antimicrobial resistance emerging trends so as to promptly inform and guide the development of effective treatment options for gonococcal infections.

Factors related to increasing prevalence of resistance to ciprofloxacin and other antimicrobial drugs in Neisseria gonorrhoeae, United States

Using data from the Gonococcal Isolate Surveillance Project, we studied changes in ciprofloxacin resistance in Neisseria gonorrhoeae isolates in the United States during 2002-2007. Compared with prevalence in heterosexual men, prevalence of ciprofloxacin-resistant N. gonorrhoeae infections showed a more pronounced increase in men who have sex with men (MSM), particularly through an increase in prevalence of strains also resistant to tetracycline and penicillin. Moreover, that multidrug resistance profile among MSM was negatively associated with recent travel. Across the surveillance project sites, first appearance of ciprofloxacin resistance in heterosexual men was positively correlated with such resistance for MSM. The increase in prevalence of ciprofloxacin resistance may have been facilitated by use of fluoroquinolones for treating gonorrhea and other conditions. The prominence of multidrug resistance suggests that using other classes of antimicrobial drugs for purposes other than treating gonorrhea helped increase the prevalence of ciprofloxacin-resistant strains that are also resistant to those drugs.

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.

Protocol for the molecular detection of antibiotic resistance mechanisms in Neisseria gonorrhoeae

Gonorrhoea is no longer an easily treatable ailment but rather is now a challenging disease in terms of antimicrobial resistance (AMR) with treatment options rapidly diminishing. The causative agent of gonorrhoea, Neisseria gonorrhoeae, has managed to develop resistance to almost every single drug used against it with the sole exception of extended spectrum cephalosporins. The situation is further exacerbated by the fact that not only are the rates of gonococcal infections on a steady rise globally, but tracking AMR is being undermined by the growing popularity of molecular methods at the expense of traditional bacterial culture in diagnostic laboratories. Recently, concerns have been raised over the emergence of a multi-resistant gonococci and the potential for untreatable gonorrhoea. Maintaining optimal epidemiological surveillance of gonococcal AMR remains an important aspect of gonorrhoea control. The development of molecular tools for tracking AMR in N. gonorrhoeae has the potential to further enhance such surveillance. In this chapter, we discuss nucleic acid amplification-based detection of AMR in gonorrhoea with a particular emphasis on chromosomal-mediated resistance to beta-lactam antibiotics.

Mechanisms of the formation of Neisseria gonorrhoeae resistance to cephalosporins

The authors provide a review of the present-day literature data on the issues of studying the mechanisms of the formation of Neisseria gonorrhoeae resistance to third-generation cephalosporins. Studies in this field are needed in connection with the occurrence of strains resistant to third-generation cephalosporins as well as low-sensitivity strains. The authors emphasize the importance of mutations in porB, penA, mtrR, penB and ponA genes in the development of Neisseria gonorrhoeae resistance to β-lactam antibiotics and describe the prospects of studying the mosaic structure of the penA gene encoding the РВР2 protein as well as spatial structure of this protein.

Genome sequencing of a Neisseria gonorrhoeae isolate of a successful international clone with decreased susceptibility and resistance to extended-spectrum cephalosporins

The recent emergence of Neisseria gonorrhoeae strains with decreased susceptibility to extended-spectrum cephalosporins is a major concern globally. We sequenced the genome of an N. gonorrhoeae multiantigen sequence typing (NG-MAST) ST1407 isolate (SM-3) with decreased susceptibility and resistance to oral extended-spectrum cephalosporins. The isolate was cultured in 2008 in San Francisco, CA, and possessed mosaic penA allele XXXIV, which is associated with an international clone that possesses decreased susceptibility as well as resistance to oral extended-spectrum cephalosporins globally. The genome sequence of strain NCCP11945 was used as a scaffold, and our assembly resulted in 91 contigs covering 2,029,064 bp (91%; >150× coverage) of the genome. Numerous instances of suspected horizontal genetic transfer events with other Neisseria species were identified, and two genes, opa and txf, acquired from nongonococcal Neisseria species, were identified. Strains possessing mosaic penA alleles (n = 108) and nonmosaic penA alleles (n = 169) from the United States and Europe (15 countries), cultured in 2002 to 2009, were screened for the presence of these genes. The opa gene was detected in most (82%) penA mosaic-containing isolates (mainly from 2007 to 2009) but not in any penA nonmosaic isolates. The txf gene was found in all strains containing opa but also in several (18%) penA nonmosaic strains. Using opa and txf as genetic markers, we identified a strain that possesses mosaic penA allele XXXIV, but the majority of its genome is not genetically related to strain SM-3. This implies that penA mosaic allele XXXIV was transferred horizontally. Such isolates also possessed decreased susceptibility and resistance to oral extended-spectrum cephalosporins. These findings support that genetic screening for particular penA mosaic alleles can be a valuable method for tracking strains with decreased susceptibility as well as resistance to oral extended-spectrum cephalosporins worldwide and that screening using only NG-MAST may not be sufficient.

In vitro activity of ertapenem versus ceftriaxone against Neisseria gonorrhoeae isolates with highly diverse ceftriaxone MIC values and effects of ceftriaxone resistance determinants: ertapenem for treatment of gonorrhea?

Clinical resistance to the currently recommended extended-spectrum cephalosporins (ESCs), the last remaining treatment options for gonorrhea, is being reported. Gonorrhea may become untreatable, and new treatment options are crucial. We investigated the in vitro activity of ertapenem, relative to ceftriaxone, against N. gonorrhoeae isolates and the effects of ESC resistance determinants on ertapenem. MICs were determined using agar dilution technique or Etest for international reference strains (n = 17) and clinical N. gonorrhoeae isolates (n = 257), which included the two extensively drug-resistant (XDR) strains H041 and F89 and additional isolates with high ESC MICs, clinical ESC resistance, and other types of clinical high-level and multidrug resistance (MDR). Genetic resistance determinants for ESCs (penA, mtrR, and penB) were sequenced. In general, the MICs of ertapenem (MIC(50) = 0.032 μg/ml; MIC(90) = 0.064 μg/ml) paralleled those of ceftriaxone (MIC(50) = 0.032 μg/ml; MIC(90) = 0.125 μg/ml). The ESC resistance determinants mainly increased the ertapenem MIC and ceftriaxone MIC at similar levels. However, the MIC ranges for ertapenem (0.002 to 0.125 μg/ml) and ceftriaxone (<0.002 to 4 μg/ml) differed, and the four (1.5%) ceftriaxone-resistant isolates (MIC = 0.5 to 4 μg/ml) had ertapenem MICs of 0.016 to 0.064 μg/ml. Accordingly, ertapenem had in vitro advantages over ceftriaxone for isolates with ceftriaxone resistance. These in vitro results suggest that ertapenem might be an effective treatment option for gonorrhea, particularly for the currently identified ESC-resistant cases and possibly in a dual antimicrobial therapy regimen. However, further knowledge regarding the genetic determinants (and their evolution) conferring resistance to both antimicrobials, and clear correlates between genetic and phenotypic laboratory parameters and clinical treatment outcomes, is essential.

The use of cephalosporins for gonorrhea: an update on the rising problem of resistance

INTRODUCTION

Over the last several years, Neisseria gonorrhoeae has developed decreased susceptibility to extended-spectrum cephalosporins worldwide. Gonococcal antimicrobial surveillance programs in multiple regions have documented the rise in N. gonorrhoeae isolates' minimum inhibitory concentrations to cephalosporins, and the first cases of ceftriaxone treatment failure have been reported. These developments have prompted the use of the term 'superbug' and concerns about the emergence of untreatable gonococcal infections.

AREAS COVERED

Since the publication of the last detailed review of the use of cephalosporins for gonorrhea in 2009, several new developments have occurred, which are detailed in this review. A variety of treatment strategies have been proposed in response to this 'superbug' threat, including increasing the dose or providing multiple doses of cephalosporins, multidrug therapy, rotating therapeutic regimens and individualized treatment based on susceptibility testing.

EXPERT OPINION

A robust public health response is needed that includes better diagnosis and treatment of pharyngeal gonorrhea, improved surveillance of antimicrobial resistance, informed treatment approaches and reduction of the global burden of gonococcal infections.

Using the Neisseria gonorrhoeae multiantigen sequence-typing method to assess strain diversity and antibiotic resistance in San Francisco, California

Urogenital Neisseria gonorrhoeae isolates (266) collected in San Francisco, CA, in 2009 were analyzed for antimicrobial susceptibility and were subsequently genotyped by N. gonorrhoeae multiantigen sequence typing (NG-MAST). Isolates of identical or closely related sequence types were found to possess highly similar phenotypes with regard to drug susceptibility. Isolates containing decreased susceptibility to oral cephalosporins were detected in 2009 and were found to contain the mosaic penA allele (XXXIV) found previously to be associated with decreased susceptibility to cephalosporins. A better understanding of the relationships between phenotypic and genotypic markers for antimicrobial resistance may be helpful to the development of effective surveillance systems for drug-resistant N. gonorrhoeae.

The lytic transglycosylases of Neisseria gonorrhoeae

Neisseria gonorrhoeae encodes five lytic transglycosylases (LTs) in the core genome, and most gonococcal strains also carry the gonococcal genetic island that encodes one or two additional LTs. These peptidoglycan (PG)-degrading enzymes are required for a number of processes that are either involved in the normal growth of the bacteria or affect the pathogenesis and gene transfer aspects of this species that make N. gonorrhoeae highly inflammatory and highly genetically variable. Systematic mutagenesis determined that two LTs are involved in producing the 1,6-anhydro PG monomers that cause the death of ciliated cells in Fallopian tubes. Here, we review the information available on these enzymes and discuss their roles in bacterial growth, cell separation, autolysis, type IV secretion, and pathogenesis.

Antibiotic resistance in Neisseria gonorrhoeae: origin, evolution, and lessons learned for the future

The strict human pathogen Neisseria gonorrhoeae has caused gonorrhea for thousands of years, and currently gonorrhea is the second most prevalent bacterial sexually transmitted infection worldwide. Given the ancient nature of N. gonorrhoeae and its unique obligate relationship with humankind over the millennia, its remarkable ability to adapt to the host immune system and cause repeated infections, and its propensity to develop resistance to all clinically useful antibiotics, the gonococcus is an ideal pathogen on which to study the evolution of bacterial pathogenesis, including antimicrobial resistance, over the long term and within the host during infection. Recently, the first gonococcus displaying high-level resistance to ceftriaxone, identified in Japan, was characterized in detail. Ceftriaxone is the last remaining option for empirical first-line treatment, and N. gonorrhoeae now seems to be evolving into a true "superbug." In the near future, gonorrhea may become untreatable in certain circumstances. Herein, the history of antibiotics used for treatment of gonorrhea, the evolution of resistance emergence in N. gonorrhoeae, the linkage between resistance and biological fitness of N. gonorrhoeae, lessons learned, and future perspectives are reviewed and discussed.

In vitro activity of the new fluoroketolide solithromycin (CEM-101) against a large collection of clinical Neisseria gonorrhoeae isolates and international reference strains, including those with high-level antimicrobial resistance: potential treatment option for gonorrhea?

Gonorrhea may become untreatable, and new treatment options are essential. We investigated the in vitro activity of the first fluoroketolide, solithromycin. Clinical Neisseria gonorrhoeae isolates and reference strains (n = 246), including the two extensively drug-resistant strains H041 and F89 and additional isolates with clinical cephalosporin resistance and multidrug resistance, were examined. The activity of solithromycin was mainly superior to that of other antimicrobials (n = 10) currently or previously recommended for gonorrhea treatment. Solithromycin might be an effective treatment option for gonorrhea.

Clonally related Neisseria gonorrhoeae isolates with decreased susceptibility to the extended-spectrum cephalosporin cefotaxime in Amsterdam, the Netherlands

From 2006 to 2008, Neisseria gonorrhoeae isolates were identified with decreased susceptibility to the extended-spectrum cephalosporin (ESC) cefotaxime among visitors of the Amsterdam sexually transmitted infections (STI) clinic, the Netherlands. Spread, clonality, and characteristics of 202 isolates were examined using antibiograms, conventional penA mosaic gene PCR, and N. gonorrhoeae multiple-locus variable-number tandem repeat analysis (NG-MLVA). A strictly defined subset was further characterized by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and sequencing of ESC resistance determinants (penA, mtrR, and porB1b). Seventy-four N. gonorrhoeae isolates with a cefotaxime MIC of >0.125 μg/ml (group A), 54 with a cefotaxime MIC of 0.125 μg/ml (group B), and a control group of 74 with a cefotaxime MIC of <0.125 μg/ml (group C) were included. Fifty-three clonally related penA mosaic-positive isolates (penicillin-binding protein 2 type XXXIV) were identified in group A (n = 47 isolates; 64%) and B (n = 6 isolates; 11%). The 53 penA mosaic-positive isolates were predominantly NG-MAST ST1407 (87%) and contained an mtrR promoter A deletion (98%) and porB1b alterations G101K/A102N. All were assigned to the same NG-MLVA cluster that comprised in total 56 isolates. A correlation was found between decreased cefotaxime susceptibility and ST1407 that was highly prevalent among visitors of the Amsterdam STI clinic. The rapid spread of this strain, which also has been identified in many other countries, might be facilitated by high-risk sexual behavior and should be monitored closely to identify potential treatment failure. Quality-assured surveillance of ESC susceptibility on the national and international levels and exploration of new drugs and/or strategies for treatment of gonorrhea are crucial.

A qualitative study of patients' use of expedited partner therapy

BACKGROUND

In randomized controlled trials of expedited partner therapy (EPT), among patients in the EPT arm, the proportion of partners believed to have taken the medication ranged from 56% to 85%. Little is known about the content of successful and unsuccessful EPT negotiations between patients and their partners. The aim of this study was to describe how patients made decisions about EPT and what they did with the EPT medication packs dispensed to them.

METHODS

We performed a qualitative study at the Baltimore City Health Department sexually transmitted disease clinics, which instituted an EPT pilot program in 2007. In-depth interviews were conducted with 31 patients, 1 week to 3 months after they had accepted EPT to bring to their partners. Taped interviews were transcribed verbatim and coded using ATLAS.ti 6 qualitative software. Codes were further combined into more comprehensive themes that were mapped onto the study's main aim.

RESULTS

Participants were innovative about how to get medication to their partners and indicated a deep sense of concern and responsibility for their partners' health. On the other hand, participants reported of being anxious about the interaction and sometimes felt that they lacked the words to talk with their partners about EPT. Some participants used EPT in unexpected ways, such as giving it to people other than their sex partners or taking it themselves.

CONCLUSIONS

Enhancing the counseling that accompanies EPT may improve patients' success in delivering it to their partners.

High-level cefixime- and ceftriaxone-resistant Neisseria gonorrhoeae in France: novel penA mosaic allele in a successful international clone causes treatment failure

Recently, the first Neisseria gonorrhoeae strain (H041) highly resistant to the expanded-spectrum cephalosporins (ESCs) ceftriaxone and cefixime, which are the last remaining options for first-line gonorrhea treatment, was isolated in Japan. Here, we confirm and characterize a second strain (F89) with high-level cefixime and ceftriaxone resistance which was isolated in France and most likely caused a treatment failure with cefixime. F89 was examined using six species-confirmatory tests, antibiograms (33 antimicrobials), porB sequencing, N. gonorrhoeae multiantigen sequence typing (NG-MAST), multilocus sequence typing (MLST), and sequencing of known gonococcal resistance determinants (penA, mtrR, penB, ponA, and pilQ). F89 was assigned to MLST sequence type 1901 (ST1901) and NG-MAST ST1407, which is a successful gonococcal clone that has spread globally. F89 has high-level resistance to cefixime (MIC = 4 μg/ml) and ceftriaxone (MIC = 1 to 2 μg/ml) and resistance to most other antimicrobials examined. A novel penA mosaic allele (penA-CI), which was penA-XXXIV with an additional A501P alteration in penicillin-binding protein 2, was the primary determinant for high-level ESC resistance, as determined by transformation into a set of recipient strains. N. gonorrhoeae appears to be emerging as a superbug, and in certain circumstances and settings, gonorrhea may become untreatable. Investigations of the biological fitness and enhanced understanding and monitoring of the ESC-resistant clones and their international transmission are required. Enhanced disease control activities, antimicrobial resistance control and surveillance worldwide, and public health response plans for global (and national) perspectives are also crucial. Nevertheless, new treatment strategies and/or drugs and, ideally, a vaccine are essential to develop for efficacious gonorrhea management.

Review and international recommendation of methods for typing neisseria gonorrhoeae isolates and their implications for improved knowledge of gonococcal epidemiology, treatment, and biology

Gonorrhea, which may become untreatable due to multiple resistance to available antibiotics, remains a public health problem worldwide. Precise methods for typing Neisseria gonorrhoeae, together with epidemiological information, are crucial for an enhanced understanding regarding issues involving epidemiology, test of cure and contact tracing, identifying core groups and risk behaviors, and recommending effective antimicrobial treatment, control, and preventive measures. This review evaluates methods for typing N. gonorrhoeae isolates and recommends various methods for different situations. Phenotypic typing methods, as well as some now-outdated DNA-based methods, have limited usefulness in differentiating between strains of N. gonorrhoeae. Genotypic methods based on DNA sequencing are preferred, and the selection of the appropriate genotypic method should be guided by its performance characteristics and whether short-term epidemiology (microepidemiology) or long-term and/or global epidemiology (macroepidemiology) matters are being investigated. Currently, for microepidemiological questions, the best methods for fast, objective, portable, highly discriminatory, reproducible, typeable, and high-throughput characterization are N. gonorrhoeae multiantigen sequence typing (NG-MAST) or full- or extended-length porB gene sequencing. However, pulsed-field gel electrophoresis (PFGE) and Opa typing can be valuable in specific situations, i.e., extreme microepidemiology, despite their limitations. For macroepidemiological studies and phylogenetic studies, DNA sequencing of chromosomal housekeeping genes, such as multilocus sequence typing (MLST), provides a more nuanced understanding.

Phenotypic and genotypic properties of Neisseria gonorrhoeae isolates in Norway in 2009: antimicrobial resistance warrants an immediate change in national management guidelines

Despite rapidly diminishing treatment options for Neisseria gonorrhoeae and high levels of ciprofloxacin resistance worldwide, Norwegian guidelines still recommend ciprofloxacin as empirical treatment for gonorrhea. The present study aimed to characterize phenotypical and genotypical properties of N. gonorrhoeae isolates in Norway in 2009. All viable N. gonorrhoeae isolates (n = 114) from six university hospitals in Norway (2009) were collected, representing 42% of all notified gonorrhea cases. Epidemiological data were collected from the Norwegian Surveillance System for Communicable Diseases and linked to phenotypical and genotypical characteristics for each N. gonorrhoeae isolate. Resistance levels to the antimicrobials examined were: ciprofloxacin 78%, azithromycin 11%, cefixime 3.5%, ceftriaxone 1.8%, and spectinomycin 0%. The minimum inhibitory concentrations of gentamicin varied from 1.5 to 8 mg/L. Forty-one (36%) of the isolates were β-lactamase-producing, 17 displayed penA mosaic alleles, and 72 different N. gonorrhoeae multiantigen sequence types (ST; 37 novel) were identified. The most common ST was ST1407 (n = 11), containing penA mosaic allele. Four of these isolates displayed intermediate susceptibility/resistance to cefixime. The N. gonorrhoeae strains circulating in Norway were highly diverse. The level of ciprofloxacin resistance was high and the Norwegian management guidelines should promptly exclude ciprofloxacin as an empirical treatment option for gonorrhea.