Epidemiology and natural history of ligase chain reaction detected chlamydial and gonococcal infections.

OBJECTIVES Ligase chain reaction (LCR) technology has dramatically increased the sensitivity of tests for sexually transmitted infections (STIs). It is unknown whether low copy infections (LCR positive, culture negative) have any clinical consequences. We assessed the clinical significance of untreated low copy Chlamydia trachomatis and Neisseria gonorrhoeae infections in a cohort of sexually active women. METHODS We studied a cohort of sexually active women followed at 6 month intervals for up to 3 years. Frozen urine specimens from 181 women with negative cultures for C. trachomatis and N. gonorrhoeae who were 'high risk' (defined as being less than 40 years old at baseline, and having either Trichomonas vaginalis at baseline or a history of more than one sexual partner during the 12 months before baseline) were tested for C. trachomatis and N. gonorrhoeae by LCR (Abbott Laboratories, Abbott Park, IL, USA). The specimens from all visits for each person were pooled and LCR was performed on the pool. Laboratory results were linked to clinical information. We also tested all urine samples obtained from patients with a positive culture. RESULTS 10 additional infections (nine C. trachomatis and one N. gonorrhoeae) were detected with LCR technique. None of the women with low copy infection had evidence of subsequent pelvic inflammatory disease or ectopic pregnancy. Pooling of urine samples resulted in a 47% decline in the number of tests performed. CONCLUSIONS Additional STIs can be identified when using LCR. Pooling of urine specimens is a cost saving technique for C. trachomatis and N. gonorrhoeae testing.