Resistance to azithromycin of Neisseria gonorrhoeae isolates from 2 cities in China

Emergence and dissemination of three mild outbreaks of Neisseria gonorrhoeae with high-level resistance to azithromycin in Barcelona, 2016-18

BACKGROUND

Neisseria gonorrhoeae (NG) isolates with high-level azithromycin resistance (HL-AziR) have emerged worldwide in recent decades, threatening the sustainability of current dual-antimicrobial therapy.

OBJECTIVES

This study aimed to characterize the first 16 NG isolates with HL-AziR in Barcelona between 2016 and 2018.

METHODS

WGS was used to identify the mechanisms of antimicrobial resistance, to establish the MLST ST, NG multiantigen sequence typing (NG-MAST) ST and NG sequence typing for antimicrobial resistance (NG-STAR) ST and to identify the clonal relatedness of the isolates with other closely related NG previously described in other countries based on a whole-genome SNP analysis approach. The sociodemographic characteristics of the patients included in the study were collected by comprehensive review of their medical records.

RESULTS

Twelve out of 16 HL-AziR isolates belonged to the MLST ST7823/NG-MAST ST5309 genotype and 4 to MLST ST9363/NG-MAST ST3935. All presented the A2059G mutation in all four alleles of the 23S rRNA gene. MLST ST7823/NG-MAST ST5309 isolates were only identified in men who have sex with women and MLST ST9363/NG-MAST ST3935 were found in MSM. Phylogenomic analysis revealed the presence of three transmission clusters of three different NG strains independently associated with sexual behaviour.

CONCLUSIONS

Our findings support the first appearance of three mild outbreaks of NG with HL-AziR in Spain. These results highlight the continuous capacity of NG to develop antimicrobial resistance and spread among sexual networks. The enhanced resolution of WGS provides valuable information for outbreak investigation, complementing the implementation of public health measures focused on the prevention and dissemination of MDR NG.

Evaluation of the accuracy of molecular assays targeting the mutation A2059G for detecting high-level azithromycin resistance in Neisseria gonorrhoeae: a systematic review and meta-analysis

BACKGROUND

Neisseria gonorrhoeae resistance to azithromycin has become a significant public health concern globally, and high-level azithromycin-resistant (HL-AzmR) isolates have emerged frequently. However, high-level azithromycin resistance is considered to be caused by mutated alleles of 23S rRNA gene at position 2059, and identification of HL-AzmR isolates mainly relies on agar dilution method or E-test method. This study aimed to assess the accuracy of the molecular assays targeting the mutation A2059G for identifying HL-AzmR isolates and thereby determine the association between the mutation and high-level azithromycin resistance.

METHODS

Two researchers independently searched six databases to identify studies published from the launch of each database to October 15, 2017. The fixed effects model was used to estimate the pooled sensitivity rate, specificity rate, positive predictive value (PPV), and negative predictive value (NPV). Summary receiver operating characteristic curves were generated, and the area under the curve (AUC) was determined to estimate the overall performance of the assays. The Deeks' test was conducted to evaluate potential publication bias.

RESULTS

Ten relevant studies were included in the meta-analysis to assess the synthetic accuracy of the molecular assays. The molecular assays had the synthetic sensitivity rate of 97.8% and the synthetic specificity rate of 99.1%. And the aggregated PPV and NPV were 96.4% and 99.5%, respectively. AUC was 0.99, suggesting a close relation existing between the mutation A2059G and high-level azithromycin resistance. This indicated that the molecular assays targeting the mutation A2059G have relatively high overall accuracy for identifying HL-AzmR N. gonor-rhoeae isolates. Publication bias was statistically significant.

CONCLUSION

The mutation A2059G is the critical factor causing high-level azithromycin resistance. Hence, molecular methods are recommended to be put into clinical practice by commercialization, which will assist clinicians to prescribe more precisely.

Increasing Resistance to Azithromycin in Neisseria gonorrhoeae in Eastern Chinese Cities: Resistance Mechanisms and Genetic Diversity among Isolates from Nanjing

Azithromycin resistance (AZM-R) of Neisseria gonorrhoeae is emerging as a clinical and public health challenge. We determined molecular characteristics of recent AZM-R Nanjing gonococcal isolates and tracked the emergence of AZM-R isolates in eastern Chinese cities in recent years. A total of 384 N. gonorrhoeae isolates from Nanjing collected from 2013 to 2014 were tested for susceptibility to AZM and six additional antibiotics; all AZM-R strains were characterized genetically for resistance determinants by sequencing and were genotyped using N. gonorrhoeae multiantigen sequence typing (NG-MAST). Among the 384 isolates, 124 (32.3%) were AZM-R. High-level resistance (MIC, ≥256 mg/liter) was present in 10.4% (40/384) of isolates, all of which possessed the A2143G mutation in all four 23S rRNA alleles. Low- to mid-level resistance (MIC, 1 to 64 mg/liter) was present in 21.9% (84/384) of isolates, 59.5% of which possessed the C2599T mutation in all four 23S rRNA alleles. The 124 AZM-R isolates were distributed in 71 different NG-MAST sequence types (STs). ST1866 was the most prevalent type in high-level AZM-R (HL-AZM-R) isolates (45% [18/40]). This study, together with previous reports, revealed that the prevalence of AZM-R in N. gonorrhoeae isolates in certain eastern Chinese cities has risen >4-fold (7% to 32%) from 2008 to 2014. The principal mechanisms of AZM resistance in recent Nanjing isolates were A2143G mutations (high-level resistance) and C2599T mutations (low- to mid-level resistance) in the 23S rRNA alleles. Characterization of NG-MAST STs and phylogenetic analysis indicated the genetic diversity of N. gonorrhoeae in Nanjing; however, ST1866 was the dominant genotype associated with HL-AZM-R isolates.

Neisseria gonorrhoeae molecular typing for understanding sexual networks and antimicrobial resistance transmission: A systematic review

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Combined molecular and epidemiological data can describe the spread of gonorrhoea.

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Sexual networks can be inferred from molecular clusters of infection.

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Gender and sexual orientation are commonly used to characterise these networks.

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Application of these data within gonorrhoea control interventions is limited.

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Future studies should focus on evaluating molecular typing data in practice.

Objectives

Neisseria gonorrhoeae (NG) is a significant global public health concern due to rising diagnoses rates and antimicrobial resistance. Molecular combined with epidemiological data have been used to understand the distribution and spread of NG, as well as relationships between cases in sexual networks, but the public health value gained from these studies is unclear. We conducted a systematic review to examine how molecular epidemiological studies have informed understanding of sexual networks and NG transmission, and subsequent public health interventions.

Methods

Five research databases were systematically searched up to 31st March 2017 for studies that used sequence-based DNA typing methods, including whole genome sequencing, and linked molecular data to patient-level epidemiological data. Data were extracted and summarised to identify common themes.

Results

Of the 49 studies included, 82% used NG Multi-antigen Sequence Typing. Gender and sexual orientation were commonly used to characterise sexual networks that were inferred using molecular clusters; clusters predominantly of one patient group often contained a small number of isolates from other patient groups. Suggested public health applications included using these data to target interventions at specific populations, confirm outbreaks, and inform partner management, but these were mainly untested.

Conclusions

Combining molecular and epidemiological data has provided insight into sexual mixing patterns, and dissemination of NG, but few studies have applied these findings to design or evaluate public health interventions. Future studies should focus on the application of molecular epidemiology in public health practice to provide evidence for how to prevent and control NG.

Genomic epidemiology and population structure of Neisseria gonorrhoeae from remote highly endemic Western Australian populations

BACKGROUND

Neisseria gonorrhoeae causes gonorrhoea, the second most commonly notified sexually transmitted infection in Australia. One of the highest notification rates of gonorrhoea is found in the remote regions of Western Australia (WA). Unlike isolates from the major Australian population centres, the remote community isolates have low rates of antimicrobial resistance (AMR). Population structure and whole-genome comparison of 59 isolates from the Western Australian N. gonorrhoeae collection were used to investigate relatedness of isolates cultured in the metropolitan and remote areas. Core genome phylogeny, multilocus sequencing typing (MLST), N. gonorrhoeae multi-antigen sequence typing (NG-MAST) and N. gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) in addition to hierarchical clustering of sequences were used to characterize the isolates.

RESULTS

Population structure analysis of the 59 isolates together with 72 isolates from an international collection, revealed six population groups suggesting that N. gonorrhoeae is a weakly clonal species. Two distinct population groups, Aus1 and Aus2, represented 63% of WA isolates and were mostly composed of the remote community isolates that carried no chromosomal AMR genotypes. In contrast, the Western Australian metropolitan isolates were frequently multi-drug resistant and belonged to population groups found in the international database, suggesting international transmission of the isolates.

CONCLUSIONS

Our study suggests that the population structure of N. gonorrhoeae is distinct between the communities in remote and metropolitan WA. Given the high rate of AMR in metropolitan regions, ongoing surveillance is essential to ensure the enduring efficacy of the empiric gonorrhoea treatment in remote WA.

WGS analysis and molecular resistance mechanisms of azithromycin-resistant (MIC >2 mg/L) Neisseria gonorrhoeae isolates in Europe from 2009 to 2014

OBJECTIVES

To elucidate the genome-based epidemiology and phylogenomics of azithromycin-resistant (MIC >2 mg/L) Neisseria gonorrhoeae strains collected in 2009-14 in Europe and clarify the azithromycin resistance mechanisms.

METHODS

Seventy-five azithromycin-resistant (MIC 4 to >256 mg/L) N. gonorrhoeae isolates collected in 17 European countries during 2009-14 were examined using antimicrobial susceptibility testing and WGS.

RESULTS

Thirty-six N. gonorrhoeae multi-antigen sequence typing STs and five phylogenomic clades, including 4-22 isolates from several countries per clade, were identified. The azithromycin target mutation A2059G (Escherichia coli numbering) was found in all four alleles of the 23S rRNA gene in all isolates with high-level azithromycin resistance (n = 4; MIC ≥256 mg/L). The C2611T mutation was identified in two to four alleles of the 23S rRNA gene in the remaining 71 isolates. Mutations in mtrR and its promoter were identified in 43 isolates, comprising isolates within the whole azithromycin MIC range. No mutations associated with azithromycin resistance were found in the rplD gene or the rplV gene and none of the macrolide resistance-associated genes [mef(A/E), ere(A), ere(B), erm(A), erm(B), erm(C) and erm(F)] were identified in any isolate.

CONCLUSIONS

Clonal spread of relatively few N. gonorrhoeae strains accounts for the majority of the azithromycin resistance (MIC >2 mg/L) in Europe. The four isolates with high-level resistance to azithromycin (MIC ≥256 mg/L) were widely separated in the phylogenomic tree and did not belong to any of the main clades. The main azithromycin resistance mechanisms were the A2059G mutation (high-level resistance) and the C2611T mutation (low- and moderate-level resistance) in the 23S rRNA gene.

Antimicrobial Resistance Expressed by Neisseria gonorrhoeae: A Major Global Public Health Problem in the 21st Century

Neisseria gonorrhoeae is a strictly human pathogen that is typically transmitted by sexual contact. The associated disease gonorrhea has plagued humankind for thousands of years, with a current estimated incidence of 78 million cases per year. Advances in antimicrobial discovery in the 1920s and 1930s leading to the discovery of sulfonamides and penicillin begun the era of effective antimicrobial treatment of gonorrhea. Unfortunately, the gonococcus developed decreased susceptibility or even resistance to these initially employed antibiotics, a trend that continued over subsequent decades with each new antibiotic that was brought into clinical practice. As this pattern of resistance has continued into the 21st century, there is now reason for great concern, especially in an era when few new antibiotics have prospects for use as treatment of gonorrhea. Here, we review the history of gonorrhea treatment regimens and gonococcal resistance to antibiotics, the mechanisms of resistance, resistance monitoring schemes that exist in different international settings, global responses to the challenge of resistance, and prospects for future treatment regimens in the 21st century.

Azithromycin-resistant Neisseria gonorrhoeae isolates in Guangzhou, China (2009-2013): coevolution with decreased susceptibilities to ceftriaxone and genetic characteristics

Background

The recent emergence of azithromycin-resistant (AZM-R) N. gonorrhoeae isolates that have coevolved decreased susceptibility to extended-spectrum cephalosporins has caused great concern. Here we investigated the prevalence of decreased susceptibility to ceftriaxone (CRO^D) in AZM-R isolates and genetically characterized AZM-R isolates in Guangzhou, China from 2009 to 2013.

Methods

The minimum inhibitory concentration (MIC) of AZM and ceftriaxone was determined using an agar-dilution method. All AZM-R isolates were screened for mutations in 23S rRNA, mtrR and penA genes and genotyped using N. gonorrhoeae multi-antigen sequence typing (NG-MAST).

Results

Of the 485 identified N. gonorrhoeae isolates, 445 (91.8 %) were isolated from male urethritis subjects, and 77 (15.9 %) were AZM-R (MIC ≥ 1 mg/L), including 33 (6.8 %) with AZM low-level resistant (AZM-LLR, MIC = 1 mg/L) and 44 (9.1 %) with AZM middle-level resistant (AZM-MLR, MIC ≥ 2 mg/L). Significantly more CRO^D (MIC ≥ 0.125 mg/L) showed in AZM-MLR isolates (43.2 %, 19/44) as compared with that in AZM-LLR isolates (18.2 %, 6/33) (p < 0.05). For the 23S rRNA, mtrR, penA or combined 23S rRNA/MtrR/penA mutations, no significant difference was found between AZM-LLR isolates and AZM-MLR isolates (P > 0.05); similar results were detected between combined AZM-LLR/CRO^D isolates and combined AZM-MLR/CRO^D isolates (P > 0.05). No mutation A2059G or AZM high-level resistant (AZM-HLR, MIC ≥ 256 mg/L) isolate was detected. Among 77 AZM-R isolates, 67 sequence types (STs) were identified by NG-MAST, of which 30 were novel. Most STs were represented by a single isolate.

Conclusions

The AZM-R together CRO^D isolates are now present in Guangzhou, China, which deserve continuous surveillance and the mechanism of concurrent resistance needs further study.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1469-3) contains supplementary material, which is available to authorized users.

Genomic Epidemiology and Molecular Resistance Mechanisms of Azithromycin-Resistant Neisseria gonorrhoeae in Canada from 1997 to 2014

The emergence of Neisseria gonorrhoeae strains with decreased susceptibility to cephalosporins and azithromycin (AZM) resistance (AZM(r)) represents a public health threat of untreatable gonorrhea infections. Genomic epidemiology through whole-genome sequencing was used to describe the emergence, dissemination, and spread of AZM(r) strains. The genomes of 213 AZM(r) and 23 AZM-susceptible N. gonorrhoeae isolates collected in Canada from 1989 to 2014 were sequenced. Core single nucleotide polymorphism (SNP) phylogenomic analysis resolved 246 isolates into 13 lineages. High-level AZM(r) (MICs ≥ 256 μg/ml) was found in 5 phylogenetically diverse isolates, all of which possessed the A2059G mutation (Escherichia coli numbering) in all four 23S rRNA alleles. One isolate with high-level AZM(r) collected in 2009 concurrently had decreased susceptibility to ceftriaxone (MIC = 0.125 μg/ml). An increase in the number of 23S rRNA alleles with the C2611T mutations (E. coli numbering) conferred low to moderate levels of AZM(r) (MICs = 2 to 4 and 8 to 32 μg/ml, respectively). Low-level AZM(r) was also associated with mtrR promoter mutations, including the -35A deletion and the presence of Neisseria meningitidis-like sequences. Geographic and temporal phylogenetic clustering indicates that emergent AZM(r) strains arise independently and can then rapidly expand clonally in a region through local sexual networks.

The Gonococcal Transcriptome during Infection of the Lower Genital Tract in Women

Gonorrhea is a highly prevalent disease resulting in significant morbidity worldwide, with an estimated 10⁶ cases reported annually. Neisseria gonorrhoeae, the causative agent of gonorrhea, colonizes and infects the human genital tract and often evades host immune mechanisms until successful antibiotic treatment is used. The alarming increase in antibiotic-resistant strains of N. gonorrhoeae, the often asymptomatic nature of this disease in women and the lack of a vaccine directed at crucial virulence determinants have prompted us to perform transcriptome analysis to understand gonococcal gene expression patterns during natural infection. We sequenced RNA extracted from cervico-vaginal lavage samples collected from women recently exposed to infected male partners and determined the complete N. gonorrhoeae transcriptome during infection of the lower genital tract in women. On average, 3.19% of total RNA isolated from female samples aligned to the N. gonorrhoeae NCCP11945 genome and 1750 gonococcal ORFs (65% of all protein-coding genes) were transcribed. High expression in vivo was observed in genes encoding antimicrobial efflux pumps, iron response, phage production, pilin structure, outer membrane structures and hypothetical proteins. A parallel analysis was performed using the same strains grown in vitro in a chemically defined media (CDM). A total of 140 genes were increased in expression during natural infection compared to growth in CDM, and 165 genes were decreased in expression. Large differences were found in gene expression profiles under each condition, particularly with genes involved in DNA and RNA processing, iron, transposase, pilin and lipoproteins. We specifically interrogated genes encoding DNA binding regulators and iron-scavenging proteins, and identified increased expression of several iron-regulated genes, including tbpAB and fbpAB, during infection in women as compared to growth in vitro, suggesting that during infection of the genital tract in women, the gonococcus is exposed to an iron deplete environment. Collectively, we demonstrate that a large portion of the gonococcal genome is expressed and regulated during mucosal infection including genes involved in regulatory functions and iron scavenging.

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).

Stemming the tide of drug-resistant Neisseria gonorrhoeae: the need for an individualized approach to treatment

Drug-resistant Neisseria gonorrhoeae poses a significant public health challenge. In recent years, gonococci resistant to first- and second-line antibiotics have spread worldwide and new strains have developed that are increasingly resistant to third-generation cephalosporins, which are currently our last line of available treatments. Given the timeline required to develop new drugs or an effective vaccine for N. gonorrhoeae, a top priority is to use the drugs that are available as effectively as possible. Currently, clinical management of gonorrhoea is based upon treatment guidelines informed by international gonococcal antimicrobial susceptibility surveillance programmes. This approach, although currently the most practical, is subject to a number of limitations since surveillance data inherently provide population-level information. As a result, basing treatment guidelines on these data can result in the prescription of more aggressive or broader treatment than is needed by individual patients and hence inadvertently contribute to the development and spread of resistance to important drugs. Clearly, methods are needed that provide patient-specific drug susceptibility information in a time frame that would allow clinicians to prescribe individualized treatment regimens for gonorrhoea. Fortunately, in recent years, there have been a number of advances in the development of rapid methods for characterizing both the genotype and the drug resistance phenotype of N. gonorrhoeae strains. Here, we review these advances and propose additional studies that would help facilitate a transition towards an individualized treatment approach for gonorrhoea.

In vitro synergy testing of novel antimicrobial combination therapies against Neisseria gonorrhoeae

BACKGROUND

Antimicrobial-resistant Neisseria gonorrhoeae is a major public health threat. Current CDC treatment guidelines for uncomplicated gonorrhoea recommend only ceftriaxone plus either azithromycin or doxycycline. Additional treatment options are needed.

METHODS

We used antibiotic gradient synergy testing (the Etest) to evaluate antimicrobial combinations that included a third-generation cephalosporin (cefixime or ceftriaxone) plus azithromycin, doxycycline, gentamicin, rifampicin or fosfomycin. We tested each combination against 28 clinical N. gonorrhoeae isolates and four control strains of varying susceptibility profiles, and compared the results with those obtained using combination antimicrobial testing using agar dilution. We calculated the fractional inhibitory concentration index (FICI) for each combination to determine synergy, the results being interpreted as follows: FICI ≤ 0.5 = synergy; FICI > 4.0 = antagonism; and FICI > 0.5-4 = indifference.

RESULTS

The combinations of a third-generation cephalosporin plus azithromycin, doxycycline, rifampicin, gentamicin or fosfomycin produced FICIs of indifference. The Etest and agar dilution methods produced comparable results.

CONCLUSIONS

Combinations of ceftriaxone plus rifampicin, gentamicin or fosfomycin may warrant further clinical investigation as treatments for gonorrhoea. Using the Etest for synergy testing is a viable method that has practical advantages over agar dilution.

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.

Characterization of azithromycin-resistant Neisseria gonorrhoeae isolated in Tokyo in 2005-2011

A total of 122 Neisseria gonorrhoeae isolated in the Tokyo metropolitan area in 2005-2011 were collected and analyzed by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and for their susceptibility to azithromycin and ceftriaxone. All 122 strains were susceptible to ceftriaxone, but 8 strains were azithromycin-resistant, defined as an azithromycin MIC ≥ 1 μg/ml. The 8 azithromycin-resistant strains were in 6 NG-MAST types, 3 strains in NG-MAST type 1407 and each of the other 5 strains in a different NG-MAST type. NG-MAST type 1407 strains are multidrug-resistant and are disseminated worldwide.

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

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

Conventional Agar-Based Culture Method, and Nucleic Acid Amplification Test (NAAT) of the cppB Gene for Detection of Neisseria gonorrhea in Pregnant Women Endocervical Swab Specimens

Background

Neisseria gonorrhea is the etiological agent of the sexually transmitted disease (STD) gonorrhea, and primarily infects the mucous membranes of the urethra, endocervix, pharynx or rectum of females which may result in substantial morbidity. N. gonorrhea also causes disseminated infection, with complications that may result in ectopic pregnancy, tubal infertility, chronic pelvic pain or maternal transmission of gonorrhea, and also increases susceptibility to HIV.

Objectives

In the present investigation, we used conventional agar-based culture method, and nucleic acid amplification of CCPB gene for detection of Neisseria gonorrhea in endocervical swabs samples collected from pregnant women studied

Patients and Methods

Endocervical swabs specimens for this study were obtained from 1100 pregnant women who presented to Shiraz (Iran) Hospitals from 2009 to 2011. In the present investigation we used conventional agar-based culture method, and nucleic acid amplification test (NAAT) of CCPB gene for detection of Neisseria gonorrhea in endocervical swabs samples collected from pregnant women studied. From each pregnant woman two endocervical swabs were taken: one swab placed in tubes containing phosphate buffered saline for Polymerase Chain Reaction, and the other to inoculate on culture media.

Results

Among 1100 endocervical swabs examined, 13 (1.18%) samples had positive results by polymerase chain reaction (PCR) on Neisseria gonorrhea CCPB gene. All endocervical swabs culture had negative results for Neisseria gonorrhea. 84 (7%) of the women had vaginal discharge, in whom PCR on endocervical swabs of these individuals had negative findings.

Conclusions

Nucleic acid amplification tests (NAATs) are very appropriate in detection of infected individuals. Detection techniques such as NAATs are independent of bacterial viability, and have a potential to limit false negative samples, therefore, in our country, the application of different laboratory diagnosis methods including NAATs with culture as gold standard for determination antimicrobial susceptibility is essential.

Emergence of increased azithromycin resistance during unsuccessful treatment of Neisseria gonorrhoeae infection with azithromycin (Portland, OR, 2011)

We describe the emergence of an azithromycin-resistant Neisseria gonorrhoeae variant in a man from Portland, Oregon, during sole treatment with 2 g azithromycin. This report highlights the ease with which gonococcal macrolide resistance can emerge, the threat of multidrug resistant N. gonorrhoeae, and the need for adherence to Centers for Disease Control and Prevention treatment guidelines.

The ticking time bomb: escalating antibiotic resistance in Neisseria gonorrhoeae is a public health disaster in waiting

From a once easily treatable infection, gonorrhoea has evolved into a challenging disease, which in future may become untreatable in certain circumstances. International spread of extensively drug-resistant gonococci would have severe public health implications. It seems clear that under the current treatment pressure from extended-spectrum cephalosporins, and owing to Neisseria gonorrhoeae's remarkable evolutionary adaptability, further rise of ceftriaxone-resistant strains around the world is inevitable. Simply increasing the doses of extended-spectrum cephalosporins will likely prove ineffective in the long run, and has been a lesson learnt for all single-agent therapies used for gonorrhoea to date. We recommend that dual therapy, especially those consisting of extended-spectrum cephalosporins and azithromycin, be adopted more widely and complemented by strengthening of antimicrobial resistance surveillance. Unless there is urgent action at international and local levels to combat the problem of N. gonorrhoeae antimicrobial resistance, we are in for gloomy times ahead in terms of gonorrhoea disease and control.