Diagnosis of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and Mycoplasma genitalium: an observational study of testing patterns, prevalence and co-infection rates in northern New Zealand.

Background This study sought to determine community prevalence, epidemiology and testing patterns for sexually transmissible infections (STI) in northern New Zealand.

METHODS: A total of 2643 samples submitted for STI testing between 26 November 2015 and 7 December 2015 underwent analysis by Aptima Combo 2 (Hologic, San Diego, CA, USA), Trichomonas vaginalis (TV), and Mycoplasma genitalium (MG) assays. Results were analysed by patient demographics.

RESULTS: Four hundred and eleven pathogens were detected from 359 patients, with Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), TV, and MG detected in 178 (6.7%), 19 (0.7%), 80 (3%) and 134 (5.1%) samples respectively. With the exception of TV, STI prevalence was highest in people <25 years of age. Infection was more common in men for NG (odds ratio (OR) 5.05, P<0.001) and CT (OR 2.72, P<0.001). Māori and Pacific ethnicity were associated with increased risk of MG (OR 1.82, P=0.006,) TV (OR 6.1, P<0.001) and CT (OR 3.31, P<0.001) infection, and TV and NG infections were more prevalent as social deprivation increased. A mismatch between testing rates and prevalence of infection was seen, with fewer tests performed for males (OR 0.2, P<0.001) than females and no difference in testing of Māori and Pacific men (3064/100000) compared with men of European background (3181/100000, OR 0.96, P=0.76), despite an increased risk of disease.

CONCLUSIONS: There are disparately low testing rates for STIs in certain high-risk groups in northern New Zealand.