Genotyping of Chlamydia trachomatis in rectal and pharyngeal specimens: identification of LGV genotypes in Finland

Abstract

Objectives: Lymphogranuloma venereum (LGV) infections caused by Chlamydia trachomatis L types have recently emerged in Europe among HIV-positive men having sex with men. Our aim was to introduce a genotyping strategy suitable for a diagnostic laboratory using nucleic acid amplification tests (NAATs) for detection of C trachomatis and to investigate the prevalence of LGV types in rectal and pharyngeal specimens in Finland.

Methods: Aptima Combo 2 (Gen-Probe) was used to detect C trachomatis in swabs. Altogether 140 C trachomatis NAAT-positive rectal and pharyngeal samples were genotyped by pmpH and ompA real-time PCR.

Results: Of the 140 NAAT-positive rectal and pharyngeal specimens, 114 (81%) were successfully typed by pmpH PCR. One hundred and four samples contained non-LGV, nine samples LGV and one sample both non-LGV and LGV C trachomatis types. The C trachomatis LGV types were mainly found in rectal samples. Six of the L types were confirmed to be genotype L2b and two were L2 with ompA PCR and sequencing.

Conclusions: Our experience suggests that genotyping C trachomatis by pmpH PCR can be introduced as a function of a diagnostic laboratory already using NAAT for detection of C trachomatis. The data show that LGV infections occur also in Finland. LGV should be taken into account when considering treatment and management of rectal C trachomatis infections.