Objectives We evaluated the prevalence of lymphogranuloma venereum (LGV) in anorectal Chlamydia trachomatis-positive French men who have sex with men (MSM) using pre-exposure prophylaxis (PrEP) for HIV. Here, we describe the clinical, biological and behavioural characteristics of these patients.

Methods Laboratories throughout French metropolitan areas performing routine testing for C. trachomatis sent positive anorectal specimens to the National Reference Centre for bacterial STIs for LGV real-time PCR targeting the pmpH gene. Identification of the C. trachomatis genovar was performed by ompA gene sequencing. For each patient, clinical, biological and sexual behaviour data were collected after obtaining written informed consent.

Results In 2017, 486 anorectal C. trachomatis-positive specimens from MSM PrEP users were analysed. A strain of genovar L was detected in 91 cases (18.7%). Patients with LGV were significantly more symptomatic, had more sexual partners and more concurrent syphilis compared with their non-LGV counterparts. OmpA gene sequencing, successful in two-thirds of anorectal C. trachomatis-positive specimens, showed that the LGV cases were mainly of variant L2b (n=33), followed by genovar L2 (n=27) and genetic L2b ompA variants (n=16). In 11 cases, the results indicated the occurrence of genetic exchange between L and non-L genovars.

Conclusions LGV was diagnosed in 18.7% of anorectal C. trachomatis-positive specimens from French MSM using PrEP. LGV testing should be carried out for MSM diagnosed with chlamydia and with a large number of sexual partners, high-risk practices and anorectal symptoms. These patients should be presumptively treated as having LGV. This is the first surveillance study of LGV among MSM PrEP users and monitoring should continue.