Abstract

Objectives: The enhanced sensitivity of nucleic acid amplification tests (NAATs) provides opportunity for estimating the prevalence of untreated Chlamydia trachomatis infections (Ct). However, the transmissibility and public health significance of some NAAT-identified infections are not known.

Methods: Adults attending an urban Emergency Department (ED) provided specimens for Ct screening using NAAT. Participants testing positive were offered follow-up including re-testing for Ct using NAAT and traditional methods, e.g. culture and direct fluorescent antibody, and treated. Partners were offered identical evaluation and treatment. Overall, 90 Ct-positive participants had one or more sexual partners enrolled.

Results: Evidence of transmission, as defined by infection concordance between partnerships, was observed among 75% of partners of index cases testing positive by both NAAT and traditional assay (N+T+) but only 45% of partners of index cases testing positive by NAAT only (N+T-) (prevalence ratio 1.7, 95% CI 1.1, 2.5). Among index participants returning for follow-up, 17% had no evidence of Ct infection by NAAT or traditional assay (median follow-up = 3 weeks).

Conclusions: A substantial proportion of positive NAAT results for chlamydial infection may be of lower transmissibility and may not persist after a short follow-up. The long-term health effects of some positive NAATs are uncertain.