The tip of the iceberg: opportunistic screening for Chlamydia trachomatis in asymptomatic patients attending a young people's health clinic reveals a high prevalence — a pilot study

Objectives: We implemented an opportunistic screening programme for Chlamydia trachomatis amongst patients presenting to a young peoples’ health service in the city of Geelong, Australia, to define the prevalence of infection and to identify specific risk factors. Methods: Over a 7-month period sexually active patients attending the young peoples’ clinic were offered C. trachomatis screening by nucleic acid amplification test. There was 100% acceptance rate among those offered the test. Patient demographics, reason for presentation at the clinic and reported symptoms were documented by the clinicians and correlated with laboratory findings. Results: 163 patients between the ages of 12–25 were tested, nine males and 154 females. The prevalence of chlamydia infection was 5.8% and was highest (16.0%) among patients presenting for the morning after pill. Inhibition of the nucleic acid amplification test occurred in 11.0% of urine samples. All patients with inhibited tests were asked to provide a repeat sample for retesting, but only 50% complied with this request. The majority of repeat samples (88.9%) had no inhibitors present and yielded a negative result. There was no correlation between symptoms and a positive chlamydia result. Conclusions: Chlamydia infection is common in young people engaging in unsafe sexual practice and cannot be predicted by the presence of symptoms. The high prevalence of infection in Geelong would make screening cost effective in this age group. Ongoing population screening of sexually active young people should be encouraged in community health centres. Inhibition of the nucleic acid amplification test was common but repeat testing of urine a few days later usually gave satisfactory results.