Rapid detection of Chlamydia trachomatis and typing of the Lymphogranuloma venereum associated L-Serovars by TaqMan PCR

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.

Mycoplasma genitalium and Chlamydia trachomatis infection among women in Southwest China: a retrospective study

Mycoplasma genitalium (MG) and Chlamydia trachomatis (CT) are the most common sexually transmitted pathogens, which can cause cervicitis, pelvic inflammation and infertility in female. In the present study, we collected the basic information, clinical results of leucorrhoea and human papillomavirus (HPV) infection of patients, who were involved in both MG and CT RNA detection in West China Second Hospital of Sichuan University from January 2019 to April 2021, ranging from 18 to 50 years old. The results showed that the infection frequencies of MG and CT were 2.6% and 6.5%, respectively. The infection rate of CT in gynaecological patients was significantly higher than that of MG (P < 0.001). Moreover, patients with CT infection often had symptoms of gynaecological diseases, while patients with MG infection remain often asymptomatic. By exploring the connection between MG or CT infection and vaginal secretions, we found that the infection of MG or CT promoted to the increase of vaginal leukocytes, and CT infection exacerbated the decrease of the number of Lactobacillus in the vagina. Further analysis suggested that independent infection and co-infection of MG or CT resulted in abnormal vaginal secretion, affecting the stability of vaginal environment, which may induce vaginal diseases. Unexpectedly, our study found no association between MG or CT infection and high-risk HPV infection. In conclusion, our study explored the infection of MG and CT among women in Southwest China for the first time, and revealed that the infection of MG or CT would affect the homeostasis of vaginal environment, which laid a foundation for the clinical diagnosis and treatment of MG and CT infection.

The silent epidemic of lymphogranuloma venereum inside the COVID-19 pandemic in Madrid, Spain, March 2020 to February 2021

Despite social distancing measures implemented in Madrid to prevent the propagation of SARS-CoV-2, a significant increase (57.1%; 28.5 to 38.5 cases/month) in cases of lymphogranuloma venereum was detected during the COVID-19 pandemic. This unusual scenario might have accelerated a shift in Chlamydia trachomatis (CT) epidemiology towards a higher proportion of L genotypes compared with non-L genotypes in CT-positive samples. Our data underscore the importance of surveillance of sexually transmitted infections during the pandemic, in particular among vulnerable populations.

Evaluation of four commercial real-time PCR assays for the detection of lymphogranuloma venereum in Chlamydia trachomatis-positive anorectal samples

OBJECTIVES

Lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) caused by Chlamydia trachomatis (CT) genovars L. The identification of LGV is of therapeutic interest because treatment requires 3 weeks of doxycycline compared with 1 week for infection with a non-L strain. The aim of this study was to evaluate the performance of four commercial real-time PCR kits in comparison with the reference methods used for LGV diagnosis by the French National Reference Centre (NRC) for bacterial STIs.

METHODS

A total of 215 French CT-positive anorectal specimens collected consecutively in 2017 were used (66 LGV and 149 non-LGV). Among these, 92 were collected from symptomatic men who have sex with men (MSM) and 123 from asymptomatic MSM using pre-exposure prophylaxis. Four commercial assays were evaluated; a single-plex assay RealCycler CHSL kit (Progenie Molecular), tested on all the specimens, and three multiplex kits, the RealCycler Universal ULCGEN (Progenie Molecular), the Allplex Genital Ulcer Assay (Seegene) and the VIASURE Haemophilus ducreyi + CT LGV Real Time PCR Detection kit (CerTest Biotec), tested on the 92 samples from symptomatic MSM. Clinical performance was determined in comparison to the in-house real time PCR targeting the pmpH and the ompA gene sequencing.

RESULTS

Overall agreement ranged between 91.3% and 100% (95% CI 83.7-100%) with very good Kappa index values (>0.8). The clinical sensitivities and specificities varied between 91% and 100% (95% CI 80.8-100%), and 97% and 100% (95% CI 87.1-100%), respectively, with some kits performing better than others.

DISCUSSION

The four assays showed very good performance for the detection of LGV on anorectal specimens.

Identification and Discrimination of Chlamydia trachomatis Ocular and Urogenital Strains and Major Phylogenetic Lineages by CtGEM Typing, A Double-Locus Genotyping Method

CtGEM typing was developed to subdivide the bacterial species Chlamydia trachomatis on the basis of genome phylogeny and anatomical tropism. The rationale was facilitation of surveillance for ocular strains, although the method is applicable to essentially any C. trachomatis surveillance application that does not require high resolution. CtGEM is a double-locus genotyping method. The loci included in the assay were identified by computerized analysis of 65 complete genomes for resolution optimized sets of single nucleotide polymorphisms (SNPs). From this, two PCR amplifiable fragments were defined. One, rg1, is within a hypothetical gene annotated as Jali-1891 within the C. trachomatis B_Jali20 genome. The other, ofr, is within the ompA gene which encodes the major outer membrane protein. Variation in rg1 is conferred by two SNPs defining four haplotypes that exhibit concordance with genome phylogeny. Variation within ofr is more complex and allows for inference of ompA genotype, either to the level of single genotype, or group of closely related genotypes. Two CtGEM formats were developed. One is based on interrogation of the two loci by high resolution melting analysis (HRMA), and the other based on analysis of the loci by Sanger sequencing. The genotypes defined identify known ocular genotypes, discriminate known ocular genotypes from each other, discriminate the major phylogenetic lineages of the species, and discriminate all ompA genotypes with the exception of closely related variants within the genotypes H, I, J cluster. The Sanger sequencing format provides slightly more resolution that the HRMA format with respect to ompA genotype. An unusual aspect of this method is that all possible combinations of rg1 haplotype, and inferred ompA genotype(s) have been given CtGEM typing numbers. This includes types that at this time have not been shown to exist.

CtGEM typing: Discrimination of Chlamydia trachomatis ocular and urogenital strains and major evolutionary lineages by high resolution melting analysis of two amplified DNA fragments

Chlamydia trachomatis infects the urogenital tract (UGT) and eyes. Anatomical tropism is correlated with variation in the major outer membrane protein encoded by ompA. Strains possessing the ocular ompA variants A, B, Ba and C are typically found within the phylogenetically coherent “classical ocular lineage”. However, variants B, Ba and C have also been found within three distinct strains in Australia, all associated with ocular disease in children and outside the classical ocular lineage. CtGEM genotyping is a method for detecting and discriminating ocular strains and also the major phylogenetic lineages. The rationale was facilitation of surveillance to inform responses to C. trachomatis detection in UGT specimens from young children. CtGEM typing is based on high resolution melting analysis (HRMA) of two PCR amplified fragments with high combinatorial resolving power, as defined by computerised comparison of 65 whole genomes. One fragment is from the hypothetical gene defined by Jali-1891 in the C. trachomatis B_Jali20 genome, while the other is from ompA. Twenty combinatorial CtGEM types have been shown to exist, and these encompass unique genotypes for all known ocular strains, and also delineate the TI and T2 major phylogenetic lineages, identify LGV strains and provide additional resolution beyond this. CtGEM typing and Sanger sequencing were compared with 42 C. trachomatis positive clinical specimens, and there were no disjunctions. CtGEM typing is a highly efficient method designed and tested using large scale comparative genomics. It divides C. trachomatis into clinically and biologically meaningful groups, and may have broad application in surveillance.

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

The evolution of Chlamydia trachomatis is mainly driven by recombination events. This fact can be fuelled by the coincidence in several European regions of the high prevalence of non-invasive urogenital genotypes and lymphogranuloma venereum (LGV) outbreaks. This scenario could modify the local epidemiology and favor the selection of new C. trachomatis variants. Quantifying the prevalence of co-infection could help to predict the potential risk in the selection of new variants with unpredictable results in pathogenesis or transmissibility. In the 2009-2013 period, 287 clinical samples with demonstrated presence of C. trachomatis were selected. They were divided in two groups. The first group was constituted by 137 samples with C. trachomatis of the LGV genotypes, and the second by the remaining 150 samples in which the presence of LGV genotypes was previously excluded. They were analyzed to detect the simultaneous presence of non-LGV genotypes based on pmpH and ompA genes. In the first group, co-infections were detected in 10.9% of the cases whereas in the second group the prevalence was 14.6%, which is the highest percentage ever described among European countries. Moreover, bioinformatic analyses suggested the presence among men who have sex with men of a pmpH-recombinant variant, similar to strains described in Seattle in 2002. This variant was the result of genetic exchange between genotypes belonging to LGV and members of G-genotype. Sequencing of other genes, phylogenetically related to pathotype, confirmed that the putative recombinant found in Madrid could have a common origin with the strains described in Seattle. Countries with a high prevalence of co-infections and high migration flows should enhance surveillance programs in at least their vulnerable population.

Performance evaluation of automated urine microscopy as a rapid, non-invasive approach for the diagnosis of non-gonococcal urethritis

OBJECTIVES

Gram-stained urethral smear (GSUS), the standard point-of-care test for non-gonococcal urethritis (NGU) is operator dependent and poorly specific. The performance of rapid automated urine flow cytometry (AUFC) of first void urine (FVU) white cell counts (UWCC) for predicting Mycoplasma genitalium and Chlamydia trachomatis urethral infections was assessed and its application to asymptomatic infection was evaluated.

METHODS

Receiver operating characteristic curve analysis, determining FVU-UWCC threshold for predicting M. genitalium or C. trachomatis infection was performed on 208 'training' samples from symptomatic patients and subsequently validated using 228 additional FVUs obtained from prospective unselected patients.

RESULTS

An optimal diagnostic threshold of >29 UWC/µL gave sensitivities and specificities for either infection of 81.5% (95% CI 65.1% to 91.6%) and 85.8% (79.5% to 90.4%), respectively, compared with 86.8% (71.1% to 95%) and 64.7% (56.9% to 71.7%), respectively, for GSUS, using the training set samples. FVU-UWCC demonstrated sensitivities and specificities of 69.2% (95% CI 48.1% to 84.9%) and 92% (87.2% to 95.2%), respectively, when using validation samples. In asymptomatic patients where GSUS was not used, AUFC would have enabled more infections to be detected compared with clinical considerations only (71.4% vs 28.6%; p=0.03). The correlation between UWCC and bacterial load was stronger for M. genitalium compared with C. trachomatis (τ=0.426, p≤0.001 vs τ=0.295, p=0.022, respectively).

CONCLUSIONS

AUFC offers improved specificity over microscopy for predicting C. trachomatis or M. genitalium infection. Universal AUFC may enable non-invasive diagnosis of asymptomatic NGU at the PoC. The degree of urethral inflammation exhibits a stronger association with pathogen load for M. genitalium compared with C. trachomatis.

Evolution, phylogeny, and molecular epidemiology of Chlamydia

The Chlamydiaceae are a family of obligate intracellular bacteria characterized by a unique biphasic developmental cycle. It encompasses the single genus Chlamydia, which involves nine species that affect a wide range of vertebral hosts, causing infections with serious impact on human health (mainly due to Chlamydia trachomatis infections) and on farming and veterinary industries. It is believed that Chlamydiales originated ∼700mya, whereas C. trachomatis likely split from the other Chlamydiaceae during the last 6mya. This corresponds to the emergence of modern human lineages, with the first descriptions of chlamydial infections as ancient as four millennia. Chlamydiaceae have undergone a massive genome reduction, on behalf of the deletional bias "use it or lose it", stabilizing at 1-1.2Mb and keeping a striking genome synteny. Their phylogeny reveals species segregation according to biological properties, with huge differences in terms of host range, tissue tropism, and disease outcomes. Genome differences rely on the occurrence of mutations in the >700 orthologous genes, as well as on events of recombination, gene loss, inversion, and paralogous expansion, affecting both a hypervariable region named the plasticity zone, and genes essentially encoding polymorphic and transmembrane head membrane proteins, type III secretion effectors and some metabolic pathways. Procedures for molecular typing are still not consensual but have allowed the knowledge of molecular epidemiology patterns for some species as well as the identification of outbreaks and emergence of successful clones for C. trachomatis. This manuscript intends to provide a comprehensive review on the evolution, phylogeny, and molecular epidemiology of Chlamydia.

Lymphogranuloma venereum in men screened for pharyngeal and rectal infection, Germany

To determine prevalence of lymphogranuloma venereum among men who have sex with men in Germany, we conducted a multicenter study during 2009–2010 and found high rates of rectal and pharyngeal infection in men positive for the causative agent, Chlamydia trachomatis. Many infections were asymptomatic. An adjusted C. trachomatis screening policy is justified in Germany.

Clinical and epidemiological characterization of a lymphogranuloma venereum outbreak in Madrid, Spain: co-circulation of two variants

The lymphogranuloma venereum (LGV) outbreak described in the Netherlands in 2003, increased the interest in the genotyping of Chlamydia trachomatis. Although international surveillance programmes were implemented, these studies slowly decreased in the following years. Now data have revealed a new accumulation of LGV cases in those European countries with extended surveillance programmes. Between March 2009 and November 2011, a study was carried out to detect LGV cases in Madrid. The study was based on screening of C. trachomatis using commercial kits, followed by real-time pmpH-PCR discriminating LGV strains, and finally ompA gene was sequenced for phylogenetic reconstruction. Ninety-four LGV infections were identified. The number of cases increased from 10 to 30 and then to 54 during 2009-2011. Incidence of LGV was strongly associated with men who have sex with men; but in 2011, LGV cases were described in women and heterosexual men. Sixty-nine patients were also human immunodeficiency virus (HIV) positive, with detectable viral loads at the moment of LGV diagnosis, suggesting a high-risk of co-transmission. In fact, in four patients the diagnosis of HIV was simultaneous with LGV infection. The conventional treatment with doxycycline was prescribed in 75 patients, although in three patients the treatment failed. The sequencing of the ompA gene permitted identification of two independent transmission nodes. One constituted by 25 sequences identical to the L2b variant, and a second node including 37 sequences identical to L2. This epidemiological situation characterized by the co-circulation of two LGV variants has not been previously described, reinforcing the need for screening and genotyping of LGV strains.

Protocol for the rapid detection of the urogenital tract mollicutes and Chlamydia with concomitant LGV-(sub)typing

Urogenital tract infections can be caused by a number of pathogens, some of which, like the obligate intracellular Chlamydia trachomatis, are difficult to culture, or the cell wall-less mollicutes, like M. hominis or Ureaplasma spp. Real-time PCR (qPCR) has become an important diagnostic tool as it enables not only the species-specific detection of the organism but also the quantification essential to define the etiological relevance of a facultative pathogenic bacterium. We developed a set of TaqMan qPCRs for the detection of the species M. genitalium and M. hominis (Mh/Mg-duplex qPCR), U. parvum and U. urealyticum (Uu/Up duplex-PCR), and C. trachomatis (CT-qPCR), and for typing of lymphogranuloma venereum-associated L-serovars of C. trachomatis (LGV-qPCR) as well as a sub-typing of L1, L2, and L3. In addition, the human gap-gene was amplified as quality control of the specimen, and a cryptic plasmid co-amplified in CT-qPCR as an inhibition control. The present protocol focuses on the step-by-step description for the establishment of these TaqMan multiplex qPCRs.

A nested multiplex polymerase chain reaction assay for the differential identification of three zooanthroponotic chlamydial strains in porcine swab samples

Porcine chlamydial infection is an enzootic infectious disease caused by multiple members of the family Chlamydiaceae (e.g. Chlamydophila abortus, Chlamydia suis, and Chlamydophila pneumoniae). Rapid and accurate differentiation of these pathogens is critical in the control and prevention of disease. The aim of the current study was to develop a nested multiplex polymerase chain reaction (nmPCR) assay to simultaneously detect the 3 chlamydial pathogens in clinical samples. In the first round of the nmPCR, 1 pair of family-specific primers were used to amplify the 1,100 base pair (bp) fragment of chlamydial ompA gene. In the second round of the nmPCR, 4 inner primers were designed for Ch. abortus, C. suis, and Ch. pneumoniae. Each pathogen produced a specific amplicon with a size of 340 bp, 526 bp, and 267 bp respectively. The assay was sensitive and specific for detecting target pathogens in both cell cultures and clinical specimens. The results, incorporated with the improved rapid DNA extraction protocol, suggest that the nmPCR could be a promising assay for differential identification of different chlamydial strains in pigs.

Mycoplasma salivarium detected in a microbial community with Candida glabrata in the biofilm of an occluded biliary stent

Mycoplasma salivarium, preferentially an inhabitant of the human oral cavity, has rarely been found in other locations associated with disease. We describe here, for what is believed to be the first time, the detection of M. salivarium, together with Candida glabrata, in an occluded biliary stent of an icteric, cholestatic patient.

Manifestations and management of lymphogranuloma venereum

PURPOSE OF REVIEW

This review was prompted by a sustained outbreak of lymphogranuloma venereum that has been observed among men who have sex with men (MSM) worldwide since 2004. Recent developments in the epidemiology, diagnosis and management of the infection are summarized.

RECENT FINDINGS

Between the early 1980s and 2003, lymphogranuloma venereum was rarely seen in the developed world. In 2003, a cluster of cases was seen in the Netherlands occurring mostly in HIV-positive MSM with high levels of sexual risk. With the assistance of novel molecular diagnostic techniques, more than a thousand cases of Chlamydia trachomatis L2 serovar disease have now been reported in MSM worldwide. Almost all have presented with rectal infection, usually manifesting as severe proctitis, with ulcer adenopathy syndrome seldom seen. Oral doxycycline remains the recommended treatment and has proven effective in the recent outbreak. Conflicting data exist regarding the prevalence of asymptomatic infection, and our understanding of the exact modes of transmission remains incomplete.

SUMMARY

Lymphogranuloma venereum appears to have reestablished endemicity among MSM populations in many industrialized nations. In the relative absence of recent publications from its traditional endemic regions it can be assumed that these populations remain afflicted by the infection as well.

Typing Chlamydia trachomatis: from egg yolk to nanotechnology

A historical review is provided of the various methods used for half a century to differentiate and type Chlamydia trachomatis strains. Typing of C. trachomatis is an important tool for revealing transmission patterns in sexual networks, and enabling association with clinical manifestations and pathogenicity. Serotyping using the major outer membrane protein (MOMP) has been the mainstay of epidemiological work for several decades. However, the development of nucleic acid amplification techniques (NAAT) and easy access to sequencing have shifted the focus from MOMP serotypes to omp1 genotypes. However, insufficient epidemiological resolution is achieved by characterization of both MOMP and omp1. This calls for new high-resolution genotyping methods applying for example a multilocus variable number tandem repeat assay (MLVA) or multilocus sequence typing (MLST). The futuristic nanotechnology already seems at hand to further simplify and automate the high-resolution genotyping method based on NAAT and sequencing of various targets in the C. trachomatis genome. Thereby, a high throughput can be achieved and more epidemiological information can be obtained. However, it is important to realize that culture of C. trachomatis may still be needed to detect and characterize new variants of C. trachomatis.