Molecular Antimicrobial Resistance Surveillance for Neisseria gonorrhoeae, Northern Territory, Australia

Abstract

Neisseria gonorrhoeae antimicrobial resistance (AMR) is a globally recognized health threat; new strategies are needed to enhance AMR surveillance. The Northern Territory of Australia is unique in that 2 different first-line therapies, based primarily on geographic location, are used for gonorrhea treatment. We tested 1,629 N. gonorrhoeae nucleic acid amplification test-positive clinical samples, collected from regions where ceftriaxone plus azithromycin or amoxicillin plus azithromycin are recommended first-line treatments, by using 8 N. gonorrhoeae AMR PCR assays. We compared results with those from routine culture-based surveillance data. PCR data confirmed an absence of ceftriaxone resistance and a low level of azithromycin resistance (0.2%), and that penicillin resistance was <5% in amoxicillin plus azithromycin regions. Rates of ciprofloxacin resistance and penicillinase-producing N. gonorrhoeae were lower when molecular methods were used. Molecular methods to detect N. gonorrhoeae AMR can increase the evidence base for treatment guidelines, particularly in settings where culture-based surveillance is limited.

Keywords: AMR; Australia; Neisseria gonorrhoeae; Northern Territory; antimicrobial drugs; antimicrobial resistance; bacteria; culture; gonococcus; gonorrhea; molecular; surveillance.

Figure 1

Collection areas for Neisseria gonorrhoeae samples within the Northern Territory of Australia, 2014. A) Heat map showing the local government areas from which the 1,629 nucleic acid amplification test–positive clinical samples were collected. B) Location of the Northern Territory within Australia. C) Location of the CAZ and ZAP regions within the Northern Territory. CAZ, ceftriaxone via intramuscular injection and oral azithromycin; ZAP, azithromycin, amoxicillin, probenecid.

Figure 2

Genotype frequency of the 456 Neisseria gonorrhoeae clinical samples taken from patients in the Northern Territory of Australia, 2014, that were successfully genotyped by using the iPLEX14SNP method (9). Presence of each genotype in the CAZ or ZAP regions is indicated. CAZ, ceftriaxone via intramuscular injection and oral azithromycin; ZAP, azithromycin, amoxicillin, probenecid.