Evaluation of four commercial real-time PCR assays for the detection of lymphogranuloma venereum in Chlamydia trachomatis-positive anorectal samples.

OBJECTIVES

Lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) caused by Chlamydia trachomatis (CT) genovars L. The identification of LGV is of therapeutic interest because treatment requires 3 weeks of doxycycline compared with 1 week for infection with a non-L strain. The aim of this study was to evaluate the performance of four commercial real-time PCR kits in comparison with the reference methods used for LGV diagnosis by the French National Reference Centre (NRC) for bacterial STIs.

METHODS

A total of 215 French CT-positive anorectal specimens collected consecutively in 2017 were used (66 LGV and 149 non-LGV). Among these, 92 were collected from symptomatic men who have sex with men (MSM) and 123 from asymptomatic MSM using pre-exposure prophylaxis. Four commercial assays were evaluated; a single-plex assay RealCycler CHSL kit (Progenie Molecular), tested on all the specimens, and three multiplex kits, the RealCycler Universal ULCGEN (Progenie Molecular), the Allplex Genital Ulcer Assay (Seegene) and the VIASURE Haemophilus ducreyi + CT LGV Real Time PCR Detection kit (CerTest Biotec), tested on the 92 samples from symptomatic MSM. Clinical performance was determined in comparison to the in-house real time PCR targeting the pmpH and the ompA gene sequencing.

RESULTS

Overall agreement ranged between 91.3% and 100% (95% CI 83.7-100%) with very good Kappa index values (>0.8). The clinical sensitivities and specificities varied between 91% and 100% (95% CI 80.8-100%), and 97% and 100% (95% CI 87.1-100%), respectively, with some kits performing better than others.

DISCUSSION: The four assays showed very good performance for the detection of LGV on anorectal specimens.