High Prevalence of Co-Infections by Invasive and Non-Invasive Chlamydia trachomatis Genotypes during the Lymphogranuloma Venereum Outbreak in Spain

Chlamydia trachomatis genomes from rectal samples: description of a new clade comprising ompA-genotype L4 from Argentina

Whole-genome analysis has provided insights into the evolution of Chlamydia trachomatis and, recently, into circulating strains that cause lymphogranuloma venereum (LGV). A large LGV outbreak of a new ompA-genotype, L2b, was first reported in Europe in the early 2000s, primarily affecting men who have sex with men (MSM), and then expanded globally. More recent work shows that this outbreak is diversifying into variants of described ompA-genotypes, with the same L2b genomic backbone. This study extends the investigation of LGV cases to Argentina and Finland. In 2017, an LGV outbreak was described in Argentina characterized by distinct genomic features shown by both ompA-genotyping and Multi-Locus Sequence Typing (MLST) analysis. We have obtained whole-genome sequences from cultured isolates and clinical samples via SureSelect (Agilent) target enrichment. Based on ompA and phylogenetic analyses, we describe further diversity within the ompA-genotype L2b clade, illustrating the transmission dynamics in Argentina and Finland. A key finding is that of a novel clade of Argentinian samples, characterized by a proposed new ompA-genotype L4. Additionally, we present the genome sequence of a non-LGV strain associated with anorectal proctitis. These findings contribute to the investigation of LGV evolution, particularly with the presence of the novel L4 lineage, and provide insights into genomic diversity and transmission dynamics of C. trachomatis.

Rapid expansion of lymphogranuloma venereum infections with fast diversification and spread of Chlamydia trachomatis L genovariants

IMPORTANCE

Numerous international organizations, including the World Health Organization, have been drawing attention to the global increase in sexually transmitted infections. Twenty years ago, lymphogranuloma venereum (LGV) was mainly considered a tropical disease; in recent decades, however, LGV has been increasingly present in high-income countries. This increase has been linked to men who have sex with men who participate in highly interconnected sexual networks, leading to a rapid spread of LGV. This study focuses on the spread of LGV, presenting the largest time series of LGV prevalence in Spain, which includes more than a thousand diagnosed cases in one large city. The number of LGV cases diagnosed was analyzed over time, and a selection of strains was subjected to molecular genotyping. The results indicate that the LGV epidemic is gradually evolving toward an increasingly complex diversification due to the selection of successful genovariants that have emerged by mutation and recombination events, suggesting that we are moving toward an unpredictable scenario.

Genetic Characterization of Non-Lymphogranuloma venereum Chlamydia trachomatis Indicates Distinct Infection Transmission Networks in Spain

Chlamydia trachomatis infection is an important public health problem. Our objective was to assess the dynamics of the transmission of this infection, analysing the distribution of circulating ompA genotypes and multilocus sequence types of C. trachomatis in Spain as a function of clinical and epidemiological variables. During 2018 and 2019, we genetically characterized C. trachomatis in tertiary hospitals in six areas in Spain (Asturias, Barcelona, Gipuzkoa, Mallorca, Seville and Zaragoza), with a catchment population of 3.050 million people. Genotypes and sequence types were obtained using polymerase chain reaction techniques that amplify a fragment of the ompA gene, and five highly variable genes (hctB, CT058, CT144, CT172 and pbpB), respectively. Amplicons were sequenced and phylogenetic analysis was conducted. We obtained genotypes in 636/698 cases (91.1%). Overall and by area, genotype E was the most common (35%). Stratifying by sex, genotypes D and G were more common among men, and genotypes F and I among women (p < 0.05). Genotypes D, G and J were more common in men who have sex with men (MSM) than in men who have sex with women (MSW), in whom the most common genotypes were E and F. The diversity index was higher in sequence typing (0.981) than in genotyping (0.791), and the most common sequence types were ST52 and ST108 in MSM, and ST30, ST148, ST276 and ST327 in MSW. Differences in genotype distribution between geographical areas were attributable to differences in population characteristics. The transmission dynamics varied with sexual behaviour: the predominant genotypes and most frequent sequence types found in MSM were different to those detected in MSW and women.

First reported lymphogranuloma venereum cases in Russia discovered in men who have sex with men attending proctologists

BACKGROUND

Several lymphogranuloma venereum (LGV) outbreaks among men who have sex with men (MSM) have been reported throughout the world since 2003. Nevertheless, no LGV cases have been internationally reported from Russia. We evaluated the prevalence of LGV among MSM attending proctologists in Moscow, Russia, and compared the LGV and non-LGV rectal Chlamydia trachomatis (CT) infections.

METHODS

MSM (n = 534) attending for proctologic care were included. Rectal specimens were sampled for CT and Neisseria gonorrhoeae (NG) by nucleic acid amplification tests (NAATs). All CT-positive patients were tested with an LGV-specific NAAT.

RESULTS

In total, 37.3% (95% CI 33.3-41.5; 199/534) of MSM were CT positive. Of these, 68.8% (95% CI 62.1-74.9; 137/199) had LGV and 31.2% (95% CI 25.1-37.9; 62/199) a non-LGV rectal CT infection. Older age (34 years vs. 31 years, p = 0.035) and group-sex practices (67.2% (92/137) vs. 33.9% (21/62), p < 0.0001) were associated with LGV. The LGV-positive MSM were also more likely to be HIV-positive (67.2% (92/137) vs. 41.9% (26/62), p = 0.001). Proctoscopy revealed ulcerative proctitis/proctocolitis in 99.3% (136/137) of LGV-positive MSM. No ulcerative or erosive proctitis was found in the MSM with non-LGV CT infection, but 58.1% (36/62) of them had anorectal disorders. Finally, mild catarrhal or hemorrhagic proctitis was diagnosed in only 21.6% (8/37) of MSM with non-LGV CT infection lacking concomitant NG or syphilis (p < 0.0001).

CONCLUSIONS

LGV is widely spread among MSM attending proctologists in Moscow. Clinically, acute LGV proctitis/proctocolitis can be difficult to distinguish from inflammatory bowel disease that leads to mismanaged LGV infections. LGV diagnostic laboratory testing is essential, however, currently mainly lacking for MSM in Russia. All MSM with CT-positive rectal specimens should be subsequently tested for LGV.

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.

Genome sequencing of Chlamydia trachomatis serovars E and F reveals substantial genetic variation

Chlamydia trachomatis (Ctr) is a bacterial pathogen that causes ocular, urogenital and lymph system infections in humans. It is highly abundant and among its serovars, E, F and D are most prevalent in sexually transmitted disease. However, the number of publicly available genome sequences of the serovars E and F, and thereby our knowledge about the molecular architecture of these serovars, is low. Here we sequenced the genomes of six E and F clinical isolates and one E lab strain, in order to study the genetic variance in these serovars. As observed before, the genomic variation inside the Ctr genomes is very low and the phylogenetic placement in comparison to publicly available genomes is as expected by ompA gene serotyping. However, we observed a large InDel carrying four to five open reading frames in one clinical E sample and in the E lab strain. We have also observed substantial variation on nucleotide and amino acid levels, especially in membrane proteins and secreted proteins. Furthermore, these two groups of proteins are also target for recombination events. One clinical F isolate was genetically heterogeneous and revealed the highest differences on nucleotide level in the pmpE gene.

Chlamydia trachomatis Strain Types Have Diversified Regionally and Globally with Evidence for Recombination across Geographic Divides

Chlamydia trachomatis (Ct) is the leading cause of bacterial sexually transmitted diseases worldwide. The Ct Multi Locus Sequence Typing (MLST) scheme is effective in differentiating strain types (ST), deciphering transmission patterns and treatment failure, and identifying recombinant strains. Here, we analyzed 323 reference and clinical samples, including 58 samples from Russia, an area that has not previously been represented in Ct typing schemes, to expand our knowledge of the global diversification of Ct STs. The 323 samples resolved into 84 unique STs, a 3.23 higher typing resolution compared to the gold standard single locus ompA genotyping. Our MLST scheme showed a high discriminatory index, D, of 0.98 (95% CI 0.97-0.99) confirming the validity of this method for typing. Phylogenetic analyses revealed distinct branches for the phenotypic diseases of lymphogranuloma venereum, urethritis and cervicitis, and a sub-branch for ocular trachoma. Consistent with these findings, single nucleotide polymorphisms were identified that significantly correlated with each phenotype. While the overall number of unique STs per region was comparable across geographies, the number of STs was greater for Russia with a significantly higher ST/sample ratio of 0.45 (95% CI: 0.35-0.53) compared to Europe or the Americas (p < 0.009), which may reflect a higher level of sexual mixing with the introduction of STs from other regions and/or reassortment of alleles. Four STs were found to be significantly associated with a particular geographic region. ST23 [p = 0.032 (95% CI: 1-23)], ST34 [p = 0.019 (95% CI: 1.1-25)]; and ST19 [p = 0.001 (95% CI: 1.7-34.7)] were significantly associated with Netherlands compared to Russia or the Americas, while ST 30 [p = 0.031 (95% CI: 1.1-17.8)] was significantly associated with the Americas. ST19 was significantly associated with Netherlands and Russia compared with the Americans [p = 0.001 (95% CI: 1.7-34.7) and p = 0.006 (95% CI: 1.5-34.6), respectively]. Additionally, recombinant strains were ubiquitous in the data set [106 (32.8%)], although Europe had a significantly higher number than Russia or the Americas (p < 0.04), the majority of which were from Amsterdam [43 (87.8%) of 49)]. The higher number of recombinants in Europe indicates selective pressure and/or adaptive diversification that will require additional studies to elucidate.

Spread of a new Chlamydia trachomatis variant from men who have sex with men to the heterosexual population after replacement and recombination in ompA and pmpH genes

OBJECTIVES

Sexually transmitted infections are frequently related to outbreaks in high-risk populations due to the dense sexual networks. We wanted to determine the dissemination of a Chlamydia trachomatis variant characterized by the pmpH-recombinant gene between L and G genotypes, which was previously described in a high-risk population.

METHODS

A total of 449 samples were analysed in two periods ranging from 2009 to 2015 for detection of the pmpH-recombinant gene. For those samples yielding positive amplification, a sampling was selected for phylogenetic reconstructions based on sequencing of five chromosomal genes.

RESULTS

Globally this variant was found in 113 of the 449 samples (25%). During the first years (2009-13), this variant was found almost exclusively in rectal samples (30/112 samples) of men who have sex with men and in only one non-rectal sample (1/63). In 2014, this variant was also found in urethral and pharyngeal samples (1/24 and 1/7, respectively). However, in 2015, an epidemiological change was observed as the proportion of this variant had increased in rectal samples (20/51; 39%) and non-rectal samples, including cervical samples (51/142; 36.4%). The molecular characterization revealed the replacement of the ompA gene belonging to subtype G in samples recovered from 2009 to 2013 by the ompA gene belonging to subtype J after 2013.

CONCLUSIONS

Our data would support the evidence that subtype J could be a 'subtype bridge' between different sexual networks, as subtype J has been found in men who have sex with men and heterosexual populations in similar proportions. This work reveals the necessity of implementing molecular surveillance in extra-rectal samples to help us understand the gaps in transmission.

The challenges of preexposure prophylaxis for bacterial sexually transmitted infections

Preexposure prophylaxis (PrEP) against HIV is currently the subject of great interest, as clinical trials have shown high efficacy in terms of decreasing transmission among men who have sex with men. Because the prevalence of bacterial sexual transmitted infections (STIs) is increasing within this community, a recent pilot study demonstrated the efficacy of reducing transmission of bacterial STIs by administering PrEP with daily doxycycline to men who have sex with men. This creative initiative raises several questions which are discussed in this review. Relevant information should be drawn from the huge amount of available epidemiologic data to identify those who could benefit from such prophylactic treatment. The choice of antimicrobial agents is crucial, as antimicrobial susceptibility of STI agents is heterogeneous. Finally, we discuss challenges to improve the control of STIs through the use of PrEP.

The L2b real-time PCR targeting the pmpH gene of Chlamydia trachomatis used for the diagnosis of lymphogranuloma venereum is not specific to L2b strains

The French Reference Centre for chlamydiae uses two real-time PCRs targeting the pmpH gene of Chlamydia trachomatis to differentiate between L strains and variant L2b, responsible for a lymphogranuloma venereum outbreak in Europe. We compared the results obtained for 122 L2b C. trachomatis-positive specimens, using the two real-time PCRs, with the sequencing of the ompA gene. Only 91 specimens were confirmed as L2b. Our results demonstrate that the lymphogranuloma venereum outbreak is no longer dominated by the variant L2b, and that many L-positive specimens were misidentified as L2b with the method used, which raises the question of its specificity.