Genomic analysis and antimicrobial resistance in Neisseria gonorrhoeae isolates from Vietnam in 2011 and 2015-16

Objectives: Antimicrobial resistance (AMR) in Neisseria gonorrhoeae, compromising gonorrhoea treatment, is a threat to sexual and reproductive health globally. South-East and East Asia have been major sources of emergence and subsequent international spread of AMR gonococcal strains during recent decades. We investigated gonococcal isolates from 2011 and 2015-16 in Vietnam (South-East Asia) using AMR testing, whole-genome sequencing (WGS), and determination of AMR determinants. Methods: Two-hundred-forty-one 241 gonococcal specimens from Vietnam were examined. Of these, 133 isolates (121 viable) were obtained in 2015-16 and 108 (all viable) in 2011. AMR testing was performed using Etest and WGS with Illumina MiSeq, according to manufacturer's instructions. Results: The resistance among the viable 2015-16 (2011) isolates was: ciprofloxacin 100% (98%), tetracycline 79% (82%), benzylpenicillin 50% (48%), cefixime 15% (1%), azithromycin 5% (32%), ceftriaxone 1% (5%), spectinomycin 0% (0%), and 18 (15%) isolates were MDR. Among the 2015-16 isolates, 28% (n=37) contained a mosaic penA allele, while no isolates had a mosaic penA allele in 2011. Phylogenomic analysis revealed introduction of two mosaic penA-containing clones (penA-10.001 or penA-34.001) after 2011, and a minor clade (eight isolates) relatively similar to the XDR strain WHO Q. Conclusions: From 2011 to 2015-16, the resistance to all currently and previously used antimicrobials except ceftriaxone, spectinomycin, and tetracycline in gonococci from Vietnam increased. Two mosaic penA-containing clones were introduced after 2011, explaining the increased cefixime resistance. Increased AMR surveillance and use of WGS for molecular epidemiology and AMR prediction for gonococcal isolates in Vietnam and other Asian countries is essential.