Efficacy of ertapenem, gentamicin, fosfomycin, and ceftriaxone for the treatment of anogenital gonorrhoea (NABOGO): a randomised, non-inferiority trial.

BACKGROUND: Neisseria gonorrhoeae causes gonorrhoea, a common sexually transmitted infection. Emerging strains resistant to first-line ceftriaxone threaten N gonorrhoeae management. Hence, alternative treatments are needed. We aimed to evaluate the efficacy of ertapenem, gentamicin, and fosfomycin as alternative treatments for anogenital N gonorrhoeae. METHODS: In a randomised, controlled, double-blind, non-inferiority trial (three experimental groups and one control group) at the Centre for Sexual Health in Amsterdam, Netherlands, we included adults aged 18 years or older, with anorectal or urogenital gonorrhoea. With random permuted blocks, participants were randomly assigned (1:1:1:1) to receive intramuscular 500 mg ceftriaxone (control group), intramuscular 1000 mg ertapenem, intramuscular 5 mg/kg gentamicin (maximum 400 mg), or oral 6 g fosfomycin. The primary outcome was the proportion of participants with a negative nucleic acid amplification test of the predefined primary infected site, 7-14 days after treatment. The primary analysis was per protocol (ie, excluding those lost to follow-up). The modified intention-to-treat analysis included all randomly assigned patients with anogenital gonorrhoea considering those lost-to-follow-up as treatment failure. Non-inferiority was established if the lower Hochberg-corrected 95% CI for difference between the experimental and control groups was greater than -10%. For the analysis of adverse events, we included all participants who received medication. The trial was registered at ClinicalTrials.gov (NCT03294395) and is complete. FINDINGS: Between Sept 18, 2017, and June 5, 2020, from 2160 patients invited to participate, we assigned 346 (16%) participants to receive either ceftriaxone (n=103), ertapenem (n=103), gentamicin (n=102), or fosfomycin (n=38). The fosfomycin group was terminated early after interim analysis revealed less than 60% efficacy. In the primary per-protocol analysis, 93 (100%) of 93 patients in the ceftriaxone group, 86 (99%) of 87 patients in the ertapenem group, 79 (93%) of 85 patients in the gentamicin group, and four (12%) of 33 patients in the fosfomycin group cleared N gonorrhoeae (risk difference vs ceftriaxone -0·01 [95% CI -0·08 to 0·05] for ertapenem and -0·07 [-0·16 to -0·01] for gentamicin). Thus, ertapenem proved non-inferior to ceftriaxone. In mITT analysis, risk differences versus ceftriaxone were -0·08 (-0·17 to 0·003) for ertapenem and -0·11 (-0·21 to -0·04) for gentamicin. We observed a higher proportion of patients with at least one adverse event in the ertapenem group (58 [56%] of 103) and fosfomycin group (36 [95%] of 38) versus the ceftriaxone group (24 [23%] of 103). INTERPRETATION: Single-dose 1000 mg ertapenem is non-inferior to single-dose 500 mg ceftriaxone in gonorrhoea treatment. Yet, 5 mg/kg gentamicin (maximum 400 mg) is not non-inferior to ceftriaxone. Ertapenem is a potential effective alternative for anogenital N gonorrhoeae infections and merits evaluation for ceftriaxone-resistant infections. FUNDING: ZonMw and GGD-Amsterdam. TRANSLATION: For the Dutch translation of the abstract see Supplementary Materials section.

Ceftriaxone Reduced Susceptible Neisseria gonorrhoeae in the Netherlands, 2009 to 2017: From PenA Mosaicism to A501T/V Nonmosaicism.

OBJECTIVES: To compare molecular and epidemiological differences between ceftriaxone-reduced susceptible (CRO-RS) and ceftriaxone-susceptible (CRO-S) N. gonorrhoeae (Ng) and to study the genetic relatedness of CRO-RS isolates. METHODS: Demographic and clinical data and samples for cultures were routinely collected from gonorrhoea patients visiting the Amsterdam STI clinic in 2009 to 2017. Ng multiantigen sequence typing (NG-MAST) and penA types were compared between CRO-RS and CRO-S Ng (frequency matched on year of isolation and sexual risk group). Minimum spanning trees were produced based on multilocus variable number of tandem repeats analysis for Ng (NG-MLVA) genotypes. RESULTS: We selected 174 CRO-RS isolates (minimum inhibitory concentration, ≥0.064 mg/L) and 174 CRO-S isolates (minimum inhibitory concentration, ≤0.016 mg/L). Demographic and clinical characteristics of patients were overall comparable between those infected with CRO-RS Ng and CRO-S Ng. However, CRO-RS isolates were more often collected from the pharyngeal site (odds ratios [OR], 3.64; P < 0.001), and patients with CRO-RS Ng were less often human immunodeficiency virus (HIV) and syphilis positive (OR, 0.63; P = 0.041 and OR, 0.58; P = 0.028, respectively). We identified 12 clusters based on NG-MLVA genotypes, including 3 large (>25 isolates) clusters predominantly containing CRO-RS isolates. Those from cluster 1 (n = 32) were mostly from 2009 to 2012 (n = 24; 75.0%), with a mosaic penA XXXIV pattern (n = 27; 84.4%) and belonging to NG-MAST genogroup G1407 (n = 24; 75.0%). Isolates from cluster 2 (n = 29) were mostly from 2013 to 2015 (n = 24; 82.7%), had a nonmosaic penA IX + A501T mutation (n = 22; 75.9%) and NG-MAST G2400 (n = 14; 48.3%). Most isolates from cluster 3 (n = 37) were from 2015 to 2017 (n = 26; 70.2%), had a nonmosaic penA IV + A501V mutation (n = 24; 64.9%) and NG-MAST G2318 (n = 22; 59.5%). CONCLUSIONS: We observed a shift in the predominant penA (from mosaic toward nonmosaic plus A501T/V mutation), NG-MAST and NG-MLVA types among CRO-RS Ng over time. This indicates a successive spread of different CRO-RS Ng clones.

Decreased Azithromycin Susceptibility of Neisseria gonorrhoeae Isolates in Patients Recently Treated with Azithromycin.

Background: Increasing azithromycin usage and resistance in Neisseria gonorrhoeae threatens current dual treatment. Because antimicrobial exposure influences resistance, we analyzed the association between azithromycin exposure and decreased susceptibility of N. gonorrhoeae. Methods: We included N. gonorrhoeae isolates of patients who visited the Amsterdam STI Clinic between 1999 and 2013 (t0), with another clinic visit in the previous 60 days (t-1). Exposure was defined as the prescription of azithromycin at t-1. Using multivariable linear regression, we assessed the association between exposure and azithromycin minimum inhibitory concentration (MIC). Whole genome sequencing (WGS) was performed to produce a phylogeny and identify multilocus sequence types (MLST), N. gonorrhoeae multiantigen sequence types (NG-MAST), and molecular markers of azithromycin resistance. Results: We included 323 isolates; 212 were unexposed to azithromycin, 14 were exposed ≤30 days, and 97 were exposed between 31 and 60 days before isolation. Mean azithromycin MIC was 0.28 mg/L (range, <0.016-24 mg/L). Linear regression adjusted for age, ethnicity, infection site, and calendar year showed a significant association between azithromycin exposure ≤30 days and MIC (ß, 1.00; 95% confidence interval, 0.44-1.56; P = .002). WGS was performed on 31 isolates: 14 unexposed, 14 exposed to azithromycin ≤30 days before isolation, and 3 t-1 isolates. Exposure to azithromycin was significantly associated with A39T or G45D mtrR mutations (P = .046) but not with MLST or NG-MAST types. Conclusions: The results suggest that frequent azithromycin use in populations at high risk of contracting N. gonorrhoeae induces an increase in MIC and may result in resistance.

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.

Trends in antimicrobial susceptibility for azithromycin and ceftriaxone in Neisseria gonorrhoeae isolates in Amsterdam, the Netherlands, between 2012 and 2015.

Resistance of Neisseria gonorrhoeae to azithromycin and ceftriaxone has been increasing in the past years. This is of concern since the combination of these antimicrobials is recommended as the first-line treatment option in most guidelines. To analyse trends in antimicrobial resistance, we retrospectively selected all consultations with a positive N. gonorrhoeae culture at the sexually transmitted infection clinic, Amsterdam, the Netherlands, from January 2012 through September 2015. Minimum inhibitory concentrations (MICs) for azithromycin and ceftriaxone were analysed per year, and determinants associated with decreased susceptibility to azithromycin (MIC > 0.25 mg/L) or ceftriaxone (MIC > 0.032 mg/L) were assessed. Between 2012 and 2015 azithromycin resistance (MIC > 0.5 mg/L) was around 1.2%, the percentage of isolates with intermediate MICs (> 0.25 and ≤ 0.5 mg/L) increased from 3.7% in 2012, to 8.6% in 2015. Determinants associated with decreased azithromycin susceptibility were, for men who have sex with men (MSM), infections diagnosed in the year 2014, two infected sites, and HIV status (HIV; associated with less decreased susceptibility); for heterosexuals this was having ≥ 10 sex partners (in previous six months). Although no ceftriaxone resistance (MIC > 0.125 mg/L) was observed during the study period, the proportion of isolates with decreased ceftriaxone susceptibility increased from 3.6% in 2012, to 8.4% in 2015. Determinants associated with decreased ceftriaxone susceptibility were, for MSM, infections diagnosed in 2014, and pharyngeal infections; and for heterosexuals, infections diagnosed in 2014 or 2015, being of female sex, and having ≥ 10 sex partners. Continued decrease of azithromycin and ceftriaxone susceptibility will threaten future treatment of gonorrhoea. Therefore, new treatment strategies are warranted.

Time to clearance of Chlamydia trachomatis RNA and DNA after treatment in patients coinfected with Neisseria gonorrhoeae - a prospective cohort study.

BACKGROUND: Performing a test of cure (TOC) could demonstrate success or failure of antimicrobial treatment of Chlamydia trachomatis infection, but recommendations for the timing of a TOC using nucleic acid amplification tests (NAATs) are inconsistent. We assessed time to clearance of C. trachomatis after treatment, using modern RNA- and DNA-based NAATs. METHODS: We analysed data from patients with a C. trachomatis and Neisseria gonorrhoeae coinfection who visited the STI Clinic Amsterdam, The Netherlands, from March through October 2014. After treatment with ceftriaxone plus either azithromycin or doxycycline, patients self-collected anal, vaginal or urine samples during 28 consecutive days. Samples were analysed using an RNA-based NAAT (Aptima Combo 2) and a DNA-based NAAT (Cobas 4800 CT/NG). We defined clearance as three consecutive negative results, and defined "blips" as isolated positive results following clearance. RESULTS: We included 23 patients with C. trachomatis and N. gonorrhoeae coinfection. All patients cleared C. trachomatis during follow-up, and we observed no reinfections. The median time to clearance (range) was 7 days (1-13) for RNA, and 6 days (1-15) for DNA. Ninety-five per cent of patients cleared RNA at day 13, and DNA at day 14. The risk of a blip after clearance was 4.4 % (RNA) and 1.7 % (DNA). CONCLUSIONS: If a TOC for anogenital chlamydia is indicated, we recommend performing it at least 14 days after initiation of treatment, when using modern RNA- and DNA-based assays. A positive result shortly after 14 days probably indicates a blip, rather than a treatment failure or a reinfection.

Test of Cure for Anogenital Gonorrhoea Using Modern RNA-Based and DNA-Based Nucleic Acid Amplification Tests: A Prospective Cohort Study.

BACKGROUND: The use of nucleic acid amplification tests (NAATs) to diagnose Neisseria gonorrhoeae infections complicates the performance of a test of cure (TOC) to monitor treatment failure, if this is indicated. As evidence for the timing of TOC using modern NAATs is limited, we performed a prospective cohort study to assess time to clearance when using modern RNA- and DNA-based NAATs. METHODS: We included patients with anogenital gonorrhoea visiting the Sexually Transmitted Infection Clinic Amsterdam from March through October 2014. After treatment with ceftriaxone mono- or dual therapy (with azithromycin or doxycycline), anal, vaginal, or urine samples were self-collected during 28 consecutive days, and analyzed using an RNA-based NAAT (Aptima Combo 2) and a DNA-based NAAT (Cobas 4800). Clearance was defined as 3 consecutive negative results, and blips as isolated positive results following clearance. RESULTS: We included 77 patients; 5 self-cleared gonorrhoea before treatment and 10 were lost to follow-up. Clearance rate of the remaining 62 patients was 100%. Median time to clearance was 2 days, with a range of 1-7 days for RNA-based NAAT and 1-15 days for DNA-based NAAT. The risk of finding a blip after clearance was 0.8% and 1.5%, respectively. One patient had a reinfection. CONCLUSIONS: If indicated, we recommend that TOC be performed for anogenital gonorrhoea at least 7 or 14 days after administering therapy, when using modern RNA- or DNA-based NAATs, respectively. When interpreting TOC results for possible treatment failure, both the occurrence of blips and a possible reinfection need to be taken into account.

Successful Combination of Nucleic Acid Amplification Test Diagnostics and Targeted Deferred Neisseria gonorrhoeae Culture.

Nucleic acid amplification tests (NAATs) are recommended for the diagnosis of N. gonorrhoeae infections because of their superior sensitivity. Increasing NAAT use causes a decline in crucial antimicrobial resistance (AMR) surveillance data, which rely on culture. We analyzed the suitability of the ESwab system for NAAT diagnostics and deferred targeted N. gonorrhoeae culture to allow selective and efficient culture based on NAAT results. We included patients visiting the STI Clinic Amsterdam, The Netherlands, in 2013. Patient characteristics and urogenital and rectal samples for direct N. gonorrhoeae culture, standard NAAT, and ESwab were collected. Standard NAAT and NAAT on ESwab samples were performed using the Aptima Combo 2 assay for N. gonorrhoeae and C. trachomatis. Two deferred N. gonorrhoeae cultures were performed on NAAT-positive ESwab samples after storage at 4°C for 1 to 3 days. We included 2,452 samples from 1,893 patients. In the standard NAAT, 107 samples were N. gonorrhoeae positive and 284 were C. trachomatis positive. The sensitivities of NAAT on ESwab samples were 83% (95% confidence interval [CI], 75 to 90%) and 87% (95% CI, 82 to 90%), respectively. ESwab samples were available for 98 of the gonorrhea-positive samples. Of these, 82% were positive in direct culture and 69% and 56% were positive in the 1st and 2nd deferred cultures, respectively (median storage times, 27 and 48 h, respectively). Deferred culture was more often successful in urogenital samples or when the patient had symptoms at the sampling site. Deferred N. gonorrhoeae culture of stored ESwab samples is feasible and enables AMR surveillance. To limit the loss in NAAT sensitivity, we recommend obtaining separate samples for NAAT and deferred culture.

Determination of in vitro synergy for dual antimicrobial therapy against resistant Neisseria gonorrhoeae using Etest and agar dilution.

In response to antimicrobial resistance of Neisseria gonorrhoeae to last-resort extended-spectrum cephalosporins, combination therapy of azithromycin+ceftriaxone is now recommended. Dual therapy can be effective to treat monoresistant strains as well as multidrug-resistant strains, preferably employing the effect of in vitro synergy. As reports on in vitro synergy of azithromycin+ceftriaxone in N. gonorrhoeae are conflicting, in this study an evaluation of this combination was performed using a cross-wise Etest method and agar dilution. Synergy was defined as a fractional inhibitory concentration index (FICI) of ≤0.5. To identify other dual treatment options for gonorrhoea, in vitro synergy was evaluated for 65 dual antimicrobial combinations using Etest. Azithromycin, cefixime, ceftriaxone, colistin, ertapenem, fosfomycin, gentamicin, minocycline, moxifloxacin, rifampicin, spectinomycin and tigecycline were screened for synergy in all possible combinations. No synergy or antagonism was found for any of the 65 combinations. The geometric mean FICI ranged from 0.82 to 2.00. The mean FICI of azithromycin+ceftriaxone was 1.18 (Etest) and 0.55 (agar dilution). The difference between both methods did not result in a difference in interpretation of synergy. Ceftriaxone-resistant strain F89 was tested in all combinations and no synergy was found for any of them. Most importantly, the ceftriaxone minimum inhibitory concentration of F89 was not decreased below the breakpoint with any concentration of azithromycin.