[Diagnosis of urogenital infection by Chlamydia trachomatis. Contribution of genetic amplification techniques]

The majority of patients with Chlamydia trachomatis infection are not aware of ther infection because they do not have symptoms. Therefore, infected individuals may not be identifiable, and chlamydial infection in men may persis for long periods, and can lead to complications such as epididymitis and prostatis. The large group of asymptomatically infected patients is not only at risk of long-term sequelate but also sustains transmission within communities. In asymptomatic and in chronic or persistent chlamydial infections, the level of Chlamydia is very low, and consequently chlamydial infections have never been easy to diagnose. The diagnosis may be based on cell culture, direct detection bacterial antigens, the nucleic acid amplification tests (NAATs) which have become the method of choice, and on the evaluation of antibody titers against various antigenic constituents. Both systemic and local antibodies in secretions can be detected in C. trachomatis infection. The introduction of assays based on amplification of genetic material has subsequently increased the sensitivity of detecting chlamydial infections and offer the opportunity to use non invasive specimens such as first void urine and semen to screen infections either in asymptomatic subjects or male partners of infertile couples. Cell culture or direct detection of bacterial antigens cannot be used for semen and urine samples and are not sensitive enough to rule out infections. Advantages of NAATs are the ability to detect even a small amount of organisms. This enables a high detection rate for C. trachomatis in symptomatic patients, in asymptomatic individuals with a low number of elementary bodies, and diagnosis of persistent infections.