(P23) Increasing prevalence and clinical presentation of the new L2b/D-Da recombinant Chlamydia trachomatis lymphogranuloma venereum (LGV) strain in British Columbia, Canada

Background: Recent identification of the transcontinental dissemination of a novel variant of lymphogranuloma venereum (LGV) has prompted broad surveillance in British Columbia (BC), Canada. Caused by a recombinant strain of Chlamydia trachomatis possessing a non-LGV ompA genotype, this strain (L2b/D-Da) has demonstrated the emergence of antimicrobial resistance and increased virulence. While the molecular profile of this strain is evolving, the clinical significance of this variant remains unknown. We aimed to compare the epidemiology and clinical presentation of L2b/D-Da LGV to non-recombinant L2b LGV.

Methods: A retrospective chart review of all LGV cases in BC from 01/2019—10/2022 was performed, the years when this variant was first identified in BC. All chlamydia-positive rectal specimens are routinely tested for LGV in BC, where positive cases additionally undergo DNA sequencing. We collected information on LGV serovar, symptoms, pre-exposure prophylaxis use, HIV status and sexual behaviours. Chi-square and Mann-Whitney tests were used to compare L2b/D-Da LGV to non-recombinant L2b LGV.

Results: Among 298 cases of LGV identified during this period, 29 (9.7%) cases were caused by the L2b/D-Da recombinant strain and 217 (72.8%) were the non-recombinant L2b serovar. Most cases were among men who have sex with men (n=288/292 [98.6%]) with a mean age of 38.5. The proportion of recombinant cases increased from 2019 to 2022 (n=4/95 [4.2%] vs. n=19/92 [19.6%]; p < 0.001). Compared to non-recombinant LGV, an elevated proportion of recombinant cases occurred among transgender women (n=3/29 [10.3%] vs. n=1/217 [0.0%]; p=0.002). A higher proportion of recombinant cases were among individuals who have sex with women, including bisexual men and transgender women (n=3/28 [10.7%] vs. n=3/212 [1.4%]; p=0.054). There was no difference in the proportion of individuals living with HIV or using PrEP. There was no difference in experiences of proctitis (n=13/25 [52.0%] vs. 111/199 [55.8%]; p=0.885), inguinal lymphadenopathy (n=0/26 [0.0%] vs. n=9/199 [4.5%]; p=0.566) or asymptomatic infection (n=9/27 [33.3%] vs. n=71/200 [35.5%]; p=0.995) between the two strains.

Conclusion: L2b/D-Da recombinant LGV is increasing, particularly among individuals who have sex with women. Though molecular studies suggest increased virulence of the strain, the clinical presentation appears to be similar to non-recombinant LGV.