Modelling response strategies for controlling gonorrhoea outbreaks in men who have sex with men in Australia.

Qibin Duan,James G Wood,Ben B Hui,Chris Carmody,David A Lewis,David G Regan,Basil Donovan,Skye Mcgregor,Rebecca J Guy,Matthew G Law,Christine Selvey,Monica M Lahra,David M Whiley,John M Kaldor,Michael Maley,David J Templeton,Anna Mcnulty,Roger Dimitri Kouyos

doi:10.1371/journal.pcbi.1009385

Abstract

The ability to treat gonorrhoea with current first-line drugs is threatened by the global spread of extensively drug resistant (XDR) Neisseria gonorrhoeae (NG) strains. In Australia, urban transmission is high among men who have sex with men (MSM) and importation of an XDR NG strain in this population could result in an epidemic that would be difficult and costly to control. An individual-based, anatomical site-specific mathematical model of NG transmission among Australian MSM was developed and used to evaluate the potential for elimination of an imported NG strain under a range of case-based and population-based test-and-treat strategies. When initiated upon detection of the imported strain, these strategies enhance the probability of elimination and reduce the outbreak size compared with current practice (current testing levels and no contact tracing). The most effective strategies combine testing targeted at regular and casual partners with increased rates of population testing. However, even with the most effective strategies, outbreaks can persist for up to 2 years post-detection. Our simulations suggest that local elimination of imported NG strains can be achieved with high probability using combined case-based and population-based test-and-treat strategies. These strategies may be an effective means of preserving current treatments in the event of wider XDR NG emergence.

Highlights

Gonorrhoea is a sexually transmissible infection (STI) caused by the bacterium Neisseria gonorrhoeae (NG)
While gonorrhoea remains readily treatable with antibiotics, there are major concerns about the threat of antimicrobial resistance arising from recent reports of treatment failure with first-line therapy and limited remaining treatment options
This is done within the framework of a realistic mathematical model of gonorrhoea spread in an men who have sex with men (MSM) community that captures cases, anatomical sites of infection and sexual contacts at an individual level, calibrated to relevant Australian epidemiological data

Summary

Introduction

Gonorrhoea is a sexually transmissible infection (STI) caused by the bacterium Neisseria gonorrhoeae (NG). Antibiotics have, for many decades, provided effective treatment for gonorrhoea. Resistance to several classes of antimicrobial agents has emerged, rendering many previously effective drugs ineffective [1]. Since 2009, reports of NG strains exhibiting resistance to ceftriaxone have generated substantial concern in national and global public health agencies [2,3]. These reports were initially sporadic but by 2017 evidence emerged of sustained spread of ceftriaxone-resistant strains harbouring a novel resistance mechanism in the form of a penA type 60.001 allele [4]. Novel antimicrobials are being trialled but are yet to be comprehensively assessed [10,11]

Methods

Results

Discussion

Conclusion