The L2b real-time PCR targeting the pmpH gene of Chlamydia trachomatis used for the diagnosis of lymphogranuloma venereum is not specific to L2b strains

Abstract

The French Reference Centre for chlamydiae uses two real-time PCRs targeting the pmpH gene of Chlamydia trachomatis to differentiate between L strains and variant L2b, responsible for a lymphogranuloma venereum outbreak in Europe. We compared the results obtained for 122 L2b C. trachomatis-positive specimens, using the two real-time PCRs, with the sequencing of the ompA gene. Only 91 specimens were confirmed as L2b. Our results demonstrate that the lymphogranuloma venereum outbreak is no longer dominated by the variant L2b, and that many L-positive specimens were misidentified as L2b with the method used, which raises the question of its specificity.

Keywords: Chlamydia trachomatis; L2b; lymphogranuloma venereum; ompA gene; pmpH gene.