Objectives Lymphogranuloma venereum (LGV) is an STI caused by Chlamydia trachomatis serovars L1-L3. In Europe, the current epidemic is caused mainly by L2b genovariant, although increasing cases associated with other L2 variants have been reported. Here, we assessed the distribution of rectal LGV genovariants among men having sex with men (MSM) in Italy.

Methods From 2016 to 2020, all the anorectal swabs collected from MSM attending the STI Clinic of St. Orsola-Malpighi Hospital in Bologna and positive for C. trachomatis were stored. LGV infection was confirmed by a pmpH PCR, and, subsequently, a fragment of the ompA gene was amplified and sequenced. Sequences were aligned to reference strains representing different LGV variants.

Results LGV cases accounted for one-third of all chlamydial rectal infections with a total prevalence of 4.1% (76/1852). Total number of LGV cases per year remained constant. LGV was mainly found in symptomatic patients (>65%), older than 30 years, with a high burden of other STIs (63.7% HIV-positive, 35.5% with concurrent rectal gonorrhoea, 19.7% with early syphilis). A decreasing trend in HIV-LGV co-infection was noticed over time. Three main LGV genovariants were detected (L2f, 46.1%; L2b, 23.0%; L2-L2b/D-Da, 16.9%), together with other known L2b variants (mainly L2bV2 and L2bV4). Two novel L2b ompA variants with non-synonymous single-nucleotide polymorphisms were found. Over time, the percentage of L2f cases dropped gradually, with a significant increase in L2-L2b/D-Da cases (p=0.04).

Conclusions In our area, LGV is endemic among MSM with different circulating genovariants. Active surveillance and genotyping programmes are needed to reduce re-establishing of LGV infection.