Chlamydia trachomatis genovariant L2b in men who have sex with men in Taiwan, 2020-2023.

OBJECTIVES

Lymphogranuloma venereum (LGV) caused by Chlamydia trachomatis genotypes L1-L3 has been resurging among men who have sex with men (MSM) and people with HIV (PWH) in Western countries. While historically attributed to tropical regions, rectal LGV has been rarely recognised in Asia, with Taiwan recently becoming the second Asian country to report cases.

METHODS

A multicentre, laboratory-based surveillance was conducted from January 2020 to December 2023 in Taiwan. Specimens were collected from MSM through syndromic testing and screening of high-risk populations. C. trachomatis was identified using commercial multiplex PCR assays, with genotyping performed through ompA gene sequencing. LGV-positive samples underwent multilocus sequence typing (MLST) following established protocols.

RESULTS

Among 446 C. trachomatis-positive samples, 391 (87.7%) underwent successful ompA sequencing. Genovariant L2b accounted for 9.7% of cases, predominantly among PWH with rectal chlamydia (18.2%). PWH accounted for 85.7% of all genovariant L2b cases. Of 38 genovariant L2b samples from 35 cases, 34 (84.2%) samples completed MLST, revealing sequence type (ST) 53 as the predominant strain (74%). ST39 and ST63 were identified as unreported STs in Western countries, along with previously reported ST58. The four identified STs formed a cluster.

CONCLUSIONS

Our findings indicate the clonal spread of C. trachomatis L2b-ST53 among MSM in Taiwan, primarily affecting PWH. The predominance of ST53 suggests potential international and domestic spread, indicative of the need for enhanced surveillance.