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

Abstract

resistance to ceftriaxone and azithromycin is increasing, which threatens the recommended dual therapy. We used molecular epidemiology to identify clusters and associations with azithromycin resistance in Amsterdam, the Netherlands. isolates ( = 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 sequencing, multiantigen sequence typing (NG-MAST), multilocus variable-number tandem-repeat analysis (NG-MLVA), and a specific PCR to detect mosaic 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 ( = 62, 89.9%, < 0.001) and were NG-MAST genogroup G2992 ( < 0.001), G5108 ( < 0.001), or G359 ( = 0.02) significantly more often than susceptible isolates and were more often part of NG-MLVA clusters ( < 0.001). Two resistant isolates (2.9%) had A2059G mutations, and five (7.3%) had wild-type 23S rRNA. No association between 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 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.

Emergence and Spread of Neisseria gonorrhoeae Strains with High-Level Resistance to Azithromycin in Taiwan from 2001 to 2018

“…However, many studies, including our present study, showed N. gonorrhoeae strains with an AZM MIC of 1 g/ml carried the C2611T mutated 23S rRNA allele or mtrR gene (5,(11)(12)(13). It is noteworthy that AZM resistance determinants were also recognized in N. gonorrhoeae isolates with AZM MICs of Ͻ1 g/ml (11,12,14). Close monitoring and further research is needed to monitor the evolution of wild-type N. gonorrhoeae.…”

Culture-free genotyping of Neisseria gonorrhoeae revealed distinct strains at different anatomical sites in a quarter of patients, the Netherlands, 2012 to 2016

“…We observed high variability in both alleles and ST in our study population, which could be due to sampling over a prolonged time period and from different risk groups (MSM and women reporting anal sex or symptoms). For example, ST2212, ST2992, ST5441 and ST5793 are more prevalent in MSM than heterosexual men or women [10,22,23]. In our study, these STs were mainly found in MSM, but eight samples with ST2992 and one with ST5793 were from women.…”

Emergence of Neisseria gonorrhoeae Strains Harboring a Novel Combination of Azithromycin-Attenuating Mutations

“…DNA sequence analysis revealed that all 14 isolates harbored the mosaic-mtr and the A2059G mutation in all four copies of their 23S rRNA gene. While investigators from many countries have reported on the A2059G mutation or the mosaic-mtr, none described these two haplotypes together (5,10,(12)(13)(14)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). The 14 isolates in this study are the first known isolates to have possessed both the A2059G mutation and the mosaic-mtr.…”

“…In the United States, the percentage of isolates with reduced cephalosporin susceptibility declined after 2012; however, the number and percentage of gonococcal isolates with reduced susceptibility to azithromycin have steadily increased since then (11). The increase in the number of N. gonorrhoeae isolates displaying elevated MICs to azithromycin is typically associated with the accumulation of genetic mutations in the multiple transferable resistance (mtr) locus or in the 23S rRNA gene (10,(12)(13)(14).…”