New Chlamydia trachomatis L2 strains identified in a recent outbreak of lymphogranuloma venereum in Vienna, Austria.

Background: Since 2003, an ongoing outbreak of lymphogranuloma venereum (LGV), caused by Chlamydia trachomatis biovar L2b, has been reported among men who have sex with men.

Methods: Twenty-four samples positive for C. trachomatis were analyzed for specific biovars and genovariants by genotyping of the variable segment (VS) 4, VS2 and VS1 regions of the outer membrane protein (omp) A. In addition we assessed the patients' sociodemographic background and clinical signs and symptoms.

Results: Twenty-four men who have sex with men presented with either anorectal or inguinal symptoms and tested positive for C. trachomatis DNA. Of these, the L2 genotype accounted for 15 patients, with a high coinfection rate with HIV (73.3%) and other sexually transmitted infections (53.4%). Analysis of the VS1, VS2, and VS4 regions of the ompA gene revealed the variant L2b in 8 patients. In 4 patients, 3 new L2 sequences were identified with nucleotide changes in the VS1, VS2, and VS4 region, respectively, defining new strains designated L2c, d, e.

Conclusions: This outbreak of LGV represents the further spread of C. trachomatis L2 infection. Sequence analysis of ompA regions shows heterogeneity of L2 variants, suggesting more than 1 source of the LGV infections diagnosed in Vienna.