High-resolution genotyping of Lymphogranuloma Venereum (LGV) strains of Chlamydia trachomatis in London using multi-locus VNTR analysis-ompA genotyping (MLVA-ompA).

BACKGROUND: Lymphogranuloma venereum (LGV) is caused by Chlamydia trachomatis strains with ompA genotypes L1 to L3. An LGV epidemic associated with the L2b genotype has emerged in the past few decades amongst men who have sex with men (MSM). C. trachomatis genotypes can be discriminated by outer membrane protein A gene (ompA) sequencing, however this method has limited resolution. This study employed a high-resolution genotyping method, namely, multi-locus tandem repeat (VNTR) analysis with ompA sequencing (MLVA-ompA), to assess the distribution of LGV MLVA-ompA genotypes amongst individuals attending genitourinary medicine (GUM) clinics in London. METHODS: Clinical specimens were collected from individuals attending eight London-based GUM clinics. Specimens that tested positive for C. trachomatis by commercial nucleic acid amplification test (NAAT) were confirmed as LGV by pmpH real-time PCR. LGV-positive DNA extracts were subsequently genotyped using MLVA-ompA. RESULTS: Two hundred and thirty DNA extracts were confirmed as LGV, and 162 (70%) yielded complete MLVA-ompA genotypes. Six LGV MLVA-ompA genotypes were identified: 1.9.2b-L2, 1.9.3b-L2b, 1.9.2b-L2b, 1.9.2b-L2b/D, 1.4a.2b-L2b, and 5.9.2b-L1. The following LGV ompA genotypes were identified (in descending order of abundance): L2, L2b, L2b/D, and L1. Eight ompA sequences with the hybrid L2b/D profile were detected. The hybrid sequence was identical to the ompA of a recombinant L2b/D strain detected in Portugal in 2017. CONCLUSIONS: The L2 ompA genotype was found to predominate in the London study population. The study detected an unusual hybrid L2b/D ompA profile that was previously reported in Portugal. We recommend further monitoring and surveillance of LGV strains within the UK population.

Reducing suspicion of sexual abuse in paediatric chlamydial conjunctivitis using ompA genotyping.

Chlamydia trachomatis is a Gram-negative bacterium that causes urogenital tract infections, and ocular infections including trachoma, neonatal conjunctivitis and adult chlamydial inclusion conjunctivitis. A positive C. trachomatis diagnosis in children often raises suspicions of sexual abuse. While outer membrane protein A (ompA) genotypes A-C are non-invasive and are associated with trachoma; ompA genotypes D-K are often associated with sexually transmitted urogenital infections or sexually acquired chlamydial conjunctivitis. A 10-year-old female presented with a 7-month history of unilateral conjunctivitis with itching, watering and hyperaemia. She had recently moved from an urban centre in Afghanistan to the UK. A conjunctival swab taken from the child tested positive for C. trachomatis Application of ompA genotyping to conjunctival swab chlamydial DNA demonstrated that the C. trachomatis had an ompA genotype C. Chlamydial strains with this ompA genotype cause trachoma and have never previously been associated with urogenital infection. This result supported cessation of child protection investigations.