A German Chlamydia trachomatis screening program employing semi-automated real-time PCR: results and perspectives

Genital Chlamydia trachomatis infection is a worldwide public health burden. A screening program for C. trachomatis was therefore initiated by the public health insurers in Germany ("Gemeinsamer Bundesausschuss", GBA) in April 2008.

To estimate C. trachomatis prevalence from screening 115,766 asymptomatic females and 20,033 female patients with unspecific abdominal pain.

Urine samples (pooled by five for the asymptomatic screening subjects) and cervical swabs were analyzed using semi-automated real-time PCR. Infection prevalence was determined separately in four categories of women, defined by health status (asymptomatic screening vs. non-screening with unspecified symptoms) and test material used. Comparative analyses were stratified by age and pregnancy status.

Experimental evaluation of the assay used revealed a detection limit of 379 genome copies/ml urine. For pooled urine samples, the positive predictive value was 100% whereas the negative predictive value equaled 98.1%. The observed infection prevalence was higher for cervical swabs than for urine samples. Prevalence estimates also differed significantly between pregnant and non-pregnant adolescents (< or = 20 years), irrespective of the test material used (10.2% vs. 7.3% for cervical swabs, 10.9% vs. 6.1% for pooled urine samples).

Our retrospective study, based upon a very large number of females from all parts of Germany, revealed a high infection prevalence in adolescents, particularly in pregnant adolescents, thereby justifying the screening directive of the German GBA.