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

Seven Years of Culture Collection of Neisseria gonorrhoeae: Antimicrobial Resistance and Molecular Epidemiology

The emergence of Neisseria gonorrhoeae isolates displaying resistance to antimicrobials, in particular to ceftriaxone monotherapy or ceftriaxone plus azithromycin, represents a global public health concern. This study aimed to analyze the trend of antimicrobial resistance in a 7-year isolate collection retrospective analysis in Italy. Molecular typing on a subsample of gonococci was also included. A total of 1,810 culture-positive gonorrhea cases, collected from 2013 to 2019, were investigated by antimicrobial susceptibility, using gradient diffusion method, and by the N. gonorrhoeae multiantigen sequence typing (NG-MAST). The majority of infections occurred among men with urogenital infections and 57.9% of male patients were men who have sex with men. Overall, the cefixime resistance remained stable during the time. An increase of azithromycin resistance was observed until 2018 (26.5%) with a slight decrease in the last year. In 2019, gonococci showing azithromycin minimum inhibitory concentration above the EUCAST epidemiological cutoff value (ECOFF) accounted for 9.9%. Ciprofloxacin resistance and penicillinase-producing N. gonorrhoeae (PPNG) percentages increased reaching 79.1% and 18.7% in 2019, respectively. The most common sequence types identified were 5,441, 1,407, 6,360, and 5,624. The predominant genogroup (G) was the 1,407; moreover, a new genogroup G13070 was also detected. A variation in the antimicrobial resistance rates and high genetic variability were observed in this study. The main phenotypic and genotypic characteristics of N. gonorrhoeae isolates were described to monitor the spread of drug-resistant gonorrhea.

Genomic Characterization of Gonococci from Different Anatomic Sites, Italy, 2007-2014

In recent decades, Neisseria gonorrhoeae has developed resistance to several antimicrobial classes. Molecular epidemiology approaches are useful for detecting emerging, often resistant, gonococcal clones. In this study, 67 N. gonorrhoeae isolates from different anatomic sites, collected over 8 years in Italy, were analyzed by whole genome sequencing (WGS). WGS was performed using the Illumina NextSeq 500 platform. Phylogenetic analysis was based on core single nucleotide polymorphism (SNP) and core genome multilocus sequence typing (cgMLST). N. gonorrhoeae multi-antigen sequence typing (NG-MAST), MLST, and N. gonorrhoeae sequence typing for antimicrobial resistance (NG-STAR) were carried out in silico using WGS data. Antimicrobial susceptibility against a four-drug panel was evaluated using a gradient diffusion method. Overall, gonococci clustered in accordance with NG-MAST, MLST, NG-STAR, and antimicrobials susceptibility profiles, but not with the site of isolation, HIV status, and patient sexual orientation. Phylogenetic analysis identified nine clades: two of them were the predominant and including gonococci of G1407 and G2400 genogroups.

Neisseria gonorrhoeae ciprofloxacin-resistant strains were associated with Chlamydia trachomatis coinfection

Aim: This study aims to characterize circulating strains to predict their relationship with sexually transmitted microorganisms, Chlamydia trachomatis, HIV, HCV, Treponema pallidum, HPV, Mycoplasmas, in an Italian multiethnic area, which has revealed a recent increase of Neisseria gonorrhoeae first-line antibiotic resistance. Materials & methods: We performed N. gonorrhoeae multiantigen sequence typing and the N. gonorrhoeae sequence typing for antimicrobial resistance. Results: We identified mutations in genes conferring resistance to cephalosporins, macrolides, fluoroquinolones through por and tbpB loci, and we reported new combinations of already known alleles. N. gonorrhoeae resistance to ciprofloxacin was associated with C. trachomatis coinfection. Conclusion: This study's data proved the utility of a routine N. gonorrhoeae molecular characterization to monitor the evolution of antibiotic resistance and to detect the most effective clinical treatment.

Prevalence of and factors associated with MDR Neisseria gonorrhoeae in England and Wales between 2004 and 2015: analysis of annual cross-sectional surveillance surveys

Objectives

To describe trends in prevalence, susceptibility profile and risk factors for MDR Neisseria gonorrhoeae (MDR-NG) in England and Wales.

Methods

Isolates from 16 242 gonorrhoea episodes at sexual health clinics within the Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) underwent antimicrobial susceptibility testing. MDR-NG was defined as resistance to ceftriaxone, cefixime or azithromycin, plus at least two of penicillin, ciprofloxacin and spectinomycin. Trends in resistance are presented for 2004-15; prevalence and logistic regression analyses for MDR-NG cover the period of the most recent treatment guideline (ceftriaxone plus azithromycin), 2011-15.

Results

Between 2004 and 2015, the proportion of N. gonorrhoeae isolates fully susceptible to all antimicrobial classes fell from 80% to 46%, with the proportion resistant to multiple (two or more) classes increasing from 7.3% to 17.5%. In 2011-15, 3.5% of isolates were MDR-NG, most of which were resistant to cefixime (100% in 2011, decreasing to 36.9% in 2015) and/or azithromycin (4.2% in 2011, increasing to 84.3% in 2015). After excluding azithromycin-resistant isolates, modal azithromycin MICs were higher in MDR versus non-MDR isolates (0.5 versus 0.125 mg/L), with similar results for ceftriaxone (modal MICs 0.03 versus ≤0.002 mg/L). After adjustment for confounders, MDR-NG was more common among isolates from heterosexual men, although absolute differences in prevalence were small [4.6% versus 3.3% (MSM) and 2.5% (women)].

Conclusions

N. gonorrhoeae is becoming less susceptible to available antimicrobials. Since 2011, a minority of isolates were MDR-NG; however, MICs of azithromycin or ceftriaxone (first-line therapies) for many of these were elevated. These findings highlight the importance of continued antimicrobial stewardship for gonorrhoea.

Doxycycline in the management of sexually transmitted infections

Doxycycline is a second-generation tetracycline, available worldwide for half a century. It is an inexpensive broad-spectrum antimicrobial agent largely used in the management of several bacterial infections, particularly involving intracellular pathogens, as well as in the treatment of acne or for the prophylaxis of malaria. Physicochemical characteristics of doxycycline (liposolubility) allow a high diffusion in the tissues and organs. It has high bioavailability and a long elimination half-life allowing oral administration of one or two daily doses. Over the last decade, the prevalence of bacterial sexually transmitted infections (STIs) (syphilis, chlamydiosis, gonorrhoea and Mycoplasma genitalium infections) has increased in most countries, mainly in MSM, many of whom are infected with HIV. In light of increasing prevalence of resistance towards first-line regimens of some STI agents and recently updated recommendations for STI management, doxycycline appears to be an attractive option compared with other available antibiotics for the treatment of some STIs due to its efficacy, good tolerability and oral administration. More recently, indications for doxycycline in STI prophylaxis have been evaluated. Considering the renewed interest of doxycycline in STI management, this review aims to update the pharmacology of, efficacy of, safety of and resistance to doxycycline in this context of use.

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.

Molecular Characterization of Penicillinase-Producing Neisseria gonorrhoeae Isolated in Two Time Periods, 2003-2004 and 2014-2015, in Italy

The emergence of antibiotic resistant strains poses a great concern for gonorrhea treatment. The aim of this study was to characterize penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates collected in Italy in two time frames, 2003-2004 and 2014-2015. A total of 80 PPNG were characterized for the bla_TEM gene variant and the plasmid type. Furthermore, gonococci were typed using Neisseria gonorrhoeae multiantigen sequence typing. Antibiotic susceptibility assay was performed for penicillin, ciprofloxacin, ceftriaxone, and spectinomycin by Etest and minimum inhibitory concentration (MIC) test strip methods. The β-lactamase production was detected using nitrocefin test. Among PPNG isolates, four bla_TEM alleles were identified as follows: bla_TEM-1, bla_TEM-228, bla_TEMP14S, and bla_TEM-135. The African plasmid possessed the bla_TEM-1, bla_TEM-228, and bla_TEMP14S, whereas bla_TEM-135 was identified in Toronto/Rio and Asian plasmids. The percentage of isolates with the bla_TEM-1-carrying African plasmid increased from 42.5% in 2003-2004 to 55% in 2014-2015; conversely, the isolates with bla_TEM-135-carrying Toronto/Rio plasmid decreased from 57.5% to 35%. Among the isolates carrying the Toronto/Rio plasmids possessing bla_TEM-135, sequence type (ST)661 and ST5624 were found to be the predominant STs in both periods 2003-2004 and 2014-2015, respectively. More than half of the PPNG isolates were resistant to ciprofloxacin. Increase in the isolates carrying the African plasmid possessing bla_TEM-1 and a parallel decrease of the bla_TEM-135-carrying Toronto/Rio plasmid was observed. Moreover, PPNG isolate harbored Toronto/Rio plasmid with bla_TEM-135 belonged mainly to two major STs (ST661 and ST5624). Given the possible role of a mutated bla_TEM gene as an additional mechanism to extended spectrum β-lactamase resistance, it is crucial to monitor gonococci carrying these resistance genes.

Time trend analysis (2009-2016) of antimicrobial susceptibility in Neisseria gonorrhoeae isolated in Italy following the introduction of the combined antimicrobial therapy

Introduction

Neisseria gonorrhoeae (NG) antimicrobial susceptibility trends to azithromycin, cefixime and ceftriaxone were analyzed, from 2009 to 2016, to monitor changing antimicrobial susceptibility concomitant with the change in prescribing practice in 2012 from cefixime, or ceftriaxone, to ceftriaxone plus azithromycin. Patient characteristics predictive to be infected by antibiotic resistant N. gonorrhoeae were estimated. Finally, the protocol for the treatment of gonorrhoea, in comparison with the international guidelines, was also evaluated.

Materials and methods

Data on NG antimicrobial resistance were obtained from a network of sexually transmitted diseases clinics and other laboratories in 12 cities in Italy. We tested the 1,433 gonococci for antimicrobial susceptibility to azithromycin, cefixime and ceftriaxone using a gradient diffusion method. Logistic-regression methods with cluster robust standard errors were used to investigate the association of resistance categories with demographic and clinical patient characteristics and to assess changes in prescribing practices. To minimize bias due to missing data, all statistical models were fitted to data with forty rounds of multiple imputation, using chained equations.

Results

The percentage of isolates resistant to cefixime was 17.10% in 2009 and declined up to 1.39% in 2016; at the same time, those resistant to azithromycin was 23.68% in 2009 and 3.00% in 2012. Starting from 2013, azithromycin resistant gonococci tended to increase up to 7.44% in 2016. No ceftriaxone resistant isolates were observed. By multivariate analysis, the men who have sex with women (MSW) and women had a proportional adjusted OR of resistance of 1.25 (95%CI: 0.90; 1.73) and 1.67 (95%CI: 1.16; 2.40), respectively, in comparison with men who have sex with men (MSM). An aOR of resistance of 0.48 (95%CI: 0.21; 1.12) among NG isolated in the pharynx, compared with those isolated in genital sites, was calculated. The proportional aOR of resistance was 0.58 (95%CI: 0.38; 0.89) for presence vs absence of co-infection and 2.00 (95%CI: 1.36; 2.96) for past history vs no history of gonorrhoea.Finally, at least for the period 2013–2016, the older, subjects with anorectal or pharyngeal gonorrhoea infection, subjects with a co-infection, subjects with a previous gonorrhoea infection were not always correctly treated.

Conclusions

Overall, our findings suggest the shifts in N. gonorrhoeae susceptibility to cefixime and azithromycin in the time frame period. First of all, the increasing rate of azithromycin resistance in 2015–2016 in NG isolated in the country need to be monitor in the future. Finally, extensive information on treatment regimens may be useful to asses treatment adherence particularly for the older subjects, subjects with an anorectal or pharyngeal infection, subjects with a co-infection and subjects with a previous history of gonorrhoea. Gonorrhoea treatment strategy should be based on the evidence obtained by the local antimicrobial surveillance system and data about treatment failures.

A Case-Control Study of Molecular Epidemiology in Relation to Azithromycin Resistance in Neisseria gonorrhoeae Isolates Collected in Amsterdam, the Netherlands, between 2008 and 2015

Neisseria gonorrhoeae resistance to ceftriaxone and azithromycin is increasing, which threatens the recommended dual therapy. We used molecular epidemiology to identify N. gonorrhoeae clusters and associations with azithromycin resistance in Amsterdam, the Netherlands. N. gonorrhoeae isolates (n = 143) were selected from patients visiting the Amsterdam STI Outpatient Clinic from January 2008 through September 2015. We included all 69 azithromycin-resistant isolates (MIC ≥ 2.0 mg/liter) and 74 frequency-matched susceptible controls (MIC ≤ 0.25 mg/liter). The methods used were 23S rRNA and mtrR sequencing, N. gonorrhoeae multiantigen sequence typing (NG-MAST), N. gonorrhoeae multilocus variable-number tandem-repeat analysis (NG-MLVA), and a specific PCR to detect mosaic penA genes. A hierarchical cluster analysis of NG-MLVA related to resistance and epidemiological characteristics was performed. Azithromycin-resistant isolates had C2611T mutations in 23S rRNA (n = 62, 89.9%, P < 0.001) and were NG-MAST genogroup G2992 (P < 0.001), G5108 (P < 0.001), or G359 (P = 0.02) significantly more often than susceptible isolates and were more often part of NG-MLVA clusters (P < 0.001). Two resistant isolates (2.9%) had A2059G mutations, and five (7.3%) had wild-type 23S rRNA. No association between mtrR mutations and azithromycin resistance was found. Twenty-four isolates, including 10 azithromycin-resistant isolates, showed reduced susceptibility to extended-spectrum cephalosporins. Of these, five contained a penA mosaic gene. Four of the five NG-MLVA clusters contained resistant and susceptible isolates. Two clusters consisting mainly of resistant isolates included strains from men who have sex with men and from heterosexual males and females. The co-occurrence of resistant and susceptible strains in NG-MLVA clusters and the frequent occurrence of resistant strains outside of clusters suggest that azithromycin resistance develops independently from the background genome.

Genetic Resistance Determinants for Cefixime and Molecular Analysis of Gonococci Isolated in Italy

A strictly defined subset of gonococci (n = 65) isolated in Italy from 2011 to 2014 was characterized by antimicrobial susceptibility for cefixime (CFM) and ceftriaxone (CRO) and by sequencing of resistance determinant genes (penA, mtrR, porB1b, ponA) for extended-spectrum cephalosporins and Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST). The penA mosaic alleles XXXIV and XXXV were found in all resistant (R) and decreased susceptibility (DS) gonococci to CFM, except for one. They were associated with an adenine deletion in the mtrR promoter plus amino acid substitutions, H105Y or G45D, in the coding region and ponA L421P. The penA mosaic allele XXXIV, and one variant, was found exclusively among genogroup (G) 1407 and its closely related sequence types (STs), as in CFM-DS as well as in CFM-R isolates. Single or combined mutation patterns in penA, mtrR, porB1b, and ponA genes were associated with different CFM susceptibility patterns and NG-MAST STs. Genotyping and antimicrobial resistance (AMR) determinant analyses can be valuable to enhance the gonococcal AMR surveillance.

Neisseria gonorrhoeae antimicrobial susceptibility in Barcelona: penA, ponA, mtrR, and porB mutations and NG-MAST sequence types associated with decreased susceptibility to cephalosporins

The aims of this study were to determine the antimicrobial susceptibility of Neisseria gonorrhoeae (NG) in our area, to analyze the molecular mechanisms involved in cephalosporins resistance, and to undertake molecular typing of our NG strains. Antimicrobial susceptibility was determined using the Etest. The genes penA, mtrR, penB, and ponA were studied. Molecular typing was performed by N. gonorrhoeae multiantigen sequence typing. Of 329 strains analyzed in 2013, none showed high-level cephalosporin resistance, but 8.2 % had resistance to cefixime [minimum inhibitory concentration (MIC) > 0.125 μg/mL] and 0.6 % to ceftriaxone (MIC > 0.125 μg/mL). Azithromycin resistance was documented in 4.3 % and ciprofloxacin resistance in 49.2 %. Among 48 strains with an MIC ≥ 0.125 μg/mL to cefixime, 58.3 % showed the penA mosaic pattern XXXIV, 98 % a Leu → Pro substitution at position 421 of the ponA gene, 100 % amino acid changes at positions 101 and 102 of the PorB1b porin, and 87.5 % of strains an adenine deletion in the promoter region of the MtrC-D-E efflux pump. A significant difference between strains with and without decreased cephalosporin susceptibility (MIC ≥ 0.125 μg/mL) was observed for these four genes. Of the 48 strains with an MIC ≥ 0.125 μg/mL to cefixime, 43.8 % belonged to the genogroup G1407 and 27.1 % belonged to the genogroup G2400. A significant association of G1407 with decreased susceptibility (MIC ≥ 0.125 μg/mL) and G2992 with susceptibility was found, and also between G1407 and mosaic pattern XXXIV and between G2400 and A501T substitution in penA. The NG resistance rate in our area is higher than the median of Europe. We have detected the emergence of G2400, which may be a source of antimicrobial resistance.

High Prevalence of Azithromycin-Resistant Neisseria gonorrhoeae Isolates With a Multidrug Resistance Phenotype in Fukuoka, Japan

BACKGROUND

The current guidelines recommend a combination of ceftriaxone and azithromycin as a first-line treatment of gonorrhea in the United States and Europe. Despite not being recommended as a first-line regimen in Japan, an oral 2-g dose of azithromycin did become available for gonococcal infections in 2009. Recently, the emergence of azithromycin-resistant Neisseria gonorrhoeae isolates has been reported in several countries, including Japan.

METHODS

Antimicrobial susceptibility testing was performed on a total of 677 clinical isolates of N. gonorrhoeae obtained from January 2010 to December 2013 in Fukuoka, Japan. A molecular analysis by N. gonorrhoeae multiantigen sequence typing was conducted on the azithromycin-resistant isolates.

RESULTS

The proportion of azithromycin-resistant isolates (minimum inhibitory concentration > 0.5 μg/mL) increased significantly from 1.8% in 2010 to 22.6% in 2013 (P < 0.001). Among 50 azithromycin-resistant isolates, 30 (60%) exhibited a resistant phenotype to multiple drugs including cefixime. The 2 predominant sequence types (STs) identified by N. gonorrhoeae multiantigen sequence typing were ST6798 (por allele 4033 and tbpB allele 110) and ST1407 (por allele 908 and tbpB allele 110) at 40.0% (20/50) and 12.0% (6/50), respectively. There was a statistically significant increase of the proportion of ST6798 from 0% (0/19) in 2010-2012 to 64.5% (20/31) in 2013 (P < 0.001).

CONCLUSIONS

Over the previous 4 years, an increasing prevalence of azithromycin-resistant N. gonorrhoeae isolates with a multidrug-resistant phenotype was observed. Furthermore, the azithromycin-resistant isolates seemed to belong to 2 predominant STs. As a result, continued surveillance of gonococci resistant to antimicrobial agents, including azithromycin in Fukuoka, Japan, is necessary.

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification and clustering of Neisseria gonorrhoeae

Background

The sexually transmitted infection gonorrhea remains a public health concern for becoming resistant to drug treatments available. The purpose of this study was to evaluate the usefulness of the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) to identify and cluster Neisseria gonorrhoeae.

From a current monitoring in Italy, as part of the European Gonococcal Antimicrobial Surveillance Programme (EURO-GASP), 93 gonococci collected from 2007 to 2012 susceptible (44 isolates) and resistant (49 isolates) to cefixime were selected. Minimum Inhibitory Concentration (MIC) values for cefixime was assessed by Etest carried out in agreement with the manufacturer’s instructions and interpreted referring to European Committee on Antimicrobial Susceptibility testing (EUCAST) clinical breakpoints criteria. Data obtained by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and the dendrogram based on the concatenation of porB and tbpB genes were evaluated. MALDI-TOF MS, to reconfirm gonorrhea identification, analyzed single colonies from freshly grown isolates and applied directly on a ground-steel MALDI target plate. For the MALDI-TOF dendrogram cluster analysis, MSPs (Main Spectrum Profile) from each isolate were created acquiring 5000 shots from 10 technical replicates obtained from bacteria extraction.

Results

Molecular typing by NG-MAST showed 28 sequence types (STs); G1407 was the predominant accounting for 75 gonococci. All the 93 gonococci, except one, were correctly identified at species level by MALDI-TOF MS and G1407 isolates were divided into two clusters.

Conclusion

MALDI-TOF MS for a real-time detection and cluster analysis of gonorrhea is a promising tool for surveillance purposes. Moreover, additional studies are required to collect more data on the performance of MALDI-TOF MS for gonococci.