Identifying factors that lead to the persistence of imported gonorrhoeae strains: a modelling study
Ben B Hui1, David M Whiley2, Basil Donovan1,3
1The Kirby Institute, UNSW Australia, Sydney, New South Wales, Australia.
Objective:
The importation of Neisseria gonorrhoeae (NG) strains from overseas is believed to be the main source of antimicrobial resistance in Australia. With recent sporadic cases of ceftriaxone-resistant gonorrhoea reported in Australia and elsewhere, we sought to model the potential for imported NG strains to persist in the men who have sex with men (MSM) population in Australia.
Methods:
We developed an individual-based model to simulate the transmission of NG in a population of urban MSM, and used this model to investigate factors contributing to the probability that an imported NG strain will persist.
Results:
The probability of the imported NG strain persisting as the result of a single importation event is less than 1%, but the probability increases to 1% if the imported NG strain is resistant to treatment, and further increases to 3.1% if the imported NG strain can also form mixed infections with the local NG strain. The probability of the imported NG strain persisting increases to 4.4% if there are at least three importation events per month within a 1-year period.
Conclusion:
The imported NG strain is unlikely to persist as a result of a single importation event. However, the probability of persistence increases if the imported NG strain is resistant to treatment, can form mixed infections with the local NG strain or there are frequent importation events. Identification of the factors that determine the likelihood of persistence of an imported NG strain could contribute to our capacity to respond appropriately and in a timely fashion.
