title: 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: Neisseria gonorrhoeaeresistance to ceftriaxone and azithromycin is increasing, which threatens the recommended dual therapy. We used molecular epidemiology to identifyN. gonorrhoeaeclusters and associations with azithromycin resistance in Amsterdam, the Netherlands.N. gonorrhoeaeisolates (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 andmtrRsequencing,N. gonorrhoeaemultiantigen sequence typing (NG-MAST),N. gonorrhoeaemultilocus variable-number tandem-repeat analysis (NG-MLVA), and a specific PCR to detect mosaicpenAgenes. 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 betweenmtrRmutations and azithromycin resistance was found. Twenty-four isolates, including 10 azithromycin-resistant isolates, showed reduced susceptibility to extended-spectrum cephalosporins. Of these, five contained apenAmosaic 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.
authors.affiliation: STI Outpatient Clinic, Department of Infectious Diseases, Public Health Service Amsterdam, Amsterdam, the Netherlands.|Department of Dermatology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Carolien M
authors.initials: CM
authors.lastname: Wind
authors.affiliation: Public Health Laboratory, Public Health Service Amsterdam, Amsterdam, the Netherlands.
authors.forename: Sylvia M
authors.initials: SM
authors.lastname: Bruisten
authors.affiliation: Department of Infectious Diseases, Public Health Service Amsterdam, Amsterdam, the Netherlands.|Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Maarten F
authors.initials: MF
authors.lastname: Schim van der Loeff
authors.affiliation: Public Health Laboratory, Public Health Service Amsterdam, Amsterdam, the Netherlands.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Dierdorp
authors.affiliation: STI Outpatient Clinic, Department of Infectious Diseases, Public Health Service Amsterdam, Amsterdam, the Netherlands.|Department of Dermatology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.|Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Henry J C
authors.initials: HJC
authors.lastname: de Vries
authors.affiliation: Public Health Laboratory, Public Health Service Amsterdam, Amsterdam, the Netherlands avdam@ggd.amsterdam.nl.|Department of Medical Microbiology, OLVG General Hospital, Amsterdam, the Netherlands.
authors.forename: Alje P
authors.initials: AP
authors.lastname: van Dam
mesh_terms: D000328:Adult; D017963:Azithromycin / Q000627:therapeutic use*; D016022:Case-Control Studies; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D017720:Molecular Epidemiology / Q000379:methods*; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000472:pathogenicity*; D009426:Netherlands; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D055815:Young Adult
chemical_list: D012338:RNA, Ribosomal, 23S; D017963:Azithromycin
keywords: 23S rRNA mutation; NG-MAST; Neisseria gonorrhoeae; antimicrobial resistance; azithromycin; sequence typing