Lymphogranuloma venereum prevalence in Sweden among men who have sex with men and characterization of Chlamydia trachomatis ompA genotypes

Clustering of Polymorphic Membrane Protein E Clade in Chlamydia trachomatis Lineages from Men Who Have Sex with Men

Several Chlamydia trachomatis lineages identified through outer membrane protein A genotyping or multilocus sequence typing have been circulating worldwide among men who have sex with men. In a study in Tokyo, Japan, we demonstrate that such lineages commonly belong to a specific polymorphic membrane protein E clade across genotypes.

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.

Update on the Epidemiology, Screening, and Management of Chlamydia trachomatis Infection

Chlamydia trachomatis infection ("chlamydia") is the most commonly diagnosed bacterial sexually transmitted infection globally, occurring in the genitals (urethra or vagina/cervix), rectum, or pharynx. If left untreated in women, genital chlamydia can ascend into the upper genital tract causing pelvic inflammatory disease, increasing their risk for ectopic pregnancy, infertility, and chronic pelvic pain. In men, chlamydia can cause epididymitis and proctitis. However, chlamydia is asymptomatic in over 80% of cases. This article provides an update on the epidemiology, natural history, and clinical manifestations of chlamydia in adults and discusses the current approaches to its management and control policy.

Fluorescent Biosensor Based on Hairpin DNA Stabilized Copper Nanoclusters for Chlamydia trachomatis Detection

Chlamydia trachomatis (C. trachomatis) is a kind of intracellular parasitic microorganism, which can causes many diseases such as trachoma. In this strategy, a specific hairpin DNA with the probe loop as specific regions to recognize C. trachomatis DNA with strong affinity was designed, and its stem consisted of 24 AT base pairs as an effective template for hairpin DNA-CuNCs formation. In the absence of C. trachomatis DNA, the detection system showed strong orange fluorescence emission peaks at 606 nm. In the presence of C. trachomatis DNA, the conformation of DNA probe changed after hybridizing with C. trachomatis DNA. Then, the amount of hairpin DNA-CuNCs was reduced and resulted in low fluorescence emission. C. trachomatis DNA displayed a significant inhibitory effect on the synthesis of fluorescent hairpin DNA-CuNCs due to the competition between C. trachomatis DNA and the specific hairpin DNA. Under the optimal experimental conditions, different concentrations of C. trachomatis were tested and the results showed a good linear relationship in the range of 50 nM to 950 nM. Moreover, the detection limit was 18.5 nM and this detection method possessed good selectivity. Finally, the fluorescent biosensor had been successfully applied to the detection of C. trachomatis target sequence in HeLa cell lysate, providing a new strategy for the detection of C. trachomatis.

Whole-Genome Enrichment and Sequencing of Chlamydia trachomatis Directly from Patient Clinical Vaginal and Rectal Swabs

Chlamydia trachomatis, an obligately intracellular bacterium, is the most prevalent cause of bacterial sexually transmitted infections (STIs) worldwide. Numbers of U.S. infections of the urogenital tract and rectum have increased annually. Because C. trachomatis is not easily cultured, comparative genomic studies are limited, restricting our understanding of strain diversity and emergence among populations globally. While Agilent SureSelect^XT target enrichment RNA bait libraries have been developed for whole-genome enrichment and sequencing of C. trachomatis directly from clinical urine, vaginal, conjunctival, and rectal samples, public access to these libraries is not available. We therefore designed an RNA bait library (34,795 120-mer probes based on 85 genomes, versus 33,619 probes using 74 genomes in a previous one) to augment organism sequencing from clinical samples that can be shared with the scientific community, enabling comparison studies. We describe the library and limit of detection for genome copy input, and we present results of 100% efficiency and high-resolution determination of recombination and identical genomes within vaginal-rectal specimen pairs in women. This workflow provides a robust approach for discerning genomic diversity and advancing our understanding of the molecular epidemiology of contemporary C. trachomatis STIs across sample types, geographic populations, sexual networks, and outbreaks associated with proctitis/proctocolitis among women and men who have sex with men.IMPORTANCE Chlamydia trachomatis is an obligate intracellular bacterium that is not easily cultured, which limits our understanding of urogenital and rectal C. trachomatis transmission and impact on morbidity. To provide a publicly available workflow for whole-genome target enrichment and sequencing of C. trachomatis directly from clinical urine, vaginal, conjunctival, and rectal specimens, we developed and report on an RNA bait library to enrich the organism from clinical samples for sequencing. We demonstrate an increased efficiency in the percentage of reads mapping to C. trachomatis and identified recombinant and identical C. trachomatis genomes in paired vaginal-rectal samples from women. Our workflow provides a robust genomic epidemiologic approach to advance our understanding of C. trachomatis strains causing ocular, urogenital, and rectal infections and to explore geo-sexual networks, outbreaks of colorectal infections among women and men who have sex with men, and the role of these strains in morbidity.

Identification of a new variant of Chlamydia trachomatis in Mexico

INTRODUCTION

Chlamydia trachomatis is one of the main etiological agents of sexually transmitted infections worldwide. In 2006, a Swedish variant of C. trachomatis (Swedish-nvCT), which has a deletion of 377bp in the plasmid, was reported. In Latin America, Swedish-nvCT infections have not been reported. We investigated the presence of Swedish-nvCT in women with infertility in Mexico.

METHODS

Swedish-nvCT was searched in 69C. trachomatis positive samples from 2339 endocervical specimens. We designed PCR primers to identify the deletion in the plasmid in the ORF1, and the presence of a repeated 44bp in the ORF3. The sample with the deletion was genotyped with the genes of the major outer membrane protein A (ompA) and the polymorphic membrane protein (pmpH).

RESULTS

The deletion was detected in one of the 69 samples positive C. trachomatis of 2339 endocervical exudates. The nucleotide sequence analysis of the ompA shows a high degree of similarity with the Swedish nvCT (98%), however the variant found belongs to serovar D. The nucleotide sequence of the pmpH gene associates to the variant found in the genitourinary pathotype of the Swedish-nvCT but in different clusters.

CONCLUSIONS

Our results revealed the presence of a new variant of C. trachomatis in Mexican patients. This variant found in Mexico belongs to serovar D based on the in silico analysis of the ompA and pmpH genes and differs to the Swedish-nvCT (serovars E). For these variants of C. trachomatis that have been found it is necessary to carry out a more detailed analysis, although the role of this mutation has not been demonstrated in the pathogenesis.

Anatomical site distribution and genotypes of Chlamydia trachomatis infecting asymptomatic men who have sex with men in northeast Thailand

Chlamydia trachomatis is a common agent of sexually transmitted infection, especially in asymptomatic extra-genital sites among men who have sex with men (MSM). This study aims to investigate anatomical site distribution and genotypes of C. trachomatis from asymptomatic MSM in northeast Thailand. Specimens were collected using swabs from anorectal, oropharyngeal, and urethral sites in 346 asymptomatic MSM. C. trachomatis infection was determined by real-time polymerase chain reaction and genotyping was based on sequences of the ompA gene. The results showed that infection by C. trachomatis was most common at the urethral site (29.1%, 101/346) followed by oropharyngeal (17.6%, 61/346) and anorectal site (17.0%, 59/346). In addition, C. trachomatis infection was significantly associated with absence of condom use (odds ratio = 1.909, 95%CI = 1.054-3.457, P = 0.033) at the urethral site. Overall 49.4% (171/346) of individuals were infected in at least one site. Infection at only the anorectum, oropharynx, or urethra was seen in 9.0, 9.3, and 18.5% of participants, respectively. Concurrent infections at anorectum/oropharynx, anorectum/urethra, oropharynx/urethra, and all three sites were 2.0, 4.3, 4.6, and 1.7%, respectively. Genotype D predominated at the anorectal and urethral sites among asymptomatic MSM in northeast Thailand. Concurrent infection in two or three anatomical sites occurred. C. trachomatis screening at all three sites in asymptomatic MSM is important and should be considered for proper treatment and prevention of transmission.

Lymphogranuloma venereum rates increased and Chlamydia trachomatis genotypes changed among men who have sex with men in Sweden 2004-2016

This study aimed to determine the incidence of lymphogranuloma venereum (LGV) in Sweden since 2004 and to study in detail a consecutive number of Chlamydia trachomatis cases in men who have sex with men (MSM) during a 10 month period (September 2014 to July 2015). LGV increased from sporadic import cases in 2004 to comprise a spread within Sweden in 2016. Initially, only the L2b ompA genotype was detected, but in 2015 half of the genotyped LGV cases were L2 genotype. The changing genotype distribution in Sweden is linked to increased LGV spread in Europe. High-resolution multilocus sequence typing of 168 C. trachomatis cases from MSM in 2015 resulted in 29 sequence types, of which 3 accounted for 49 % of cases. The increased rates and different genotypes of LGV indicate that more concern for high-risk taking MSM is needed to avoid further spread of this invasive infection.

Molecular typing of Chlamydia trachomatis: An overview

Urogenital infection due to Chlamydia trachomatis (CT) is one of the most common bacterial sexually transmitted infections (STIs) and is a major public health problem worldwide. Molecular characterisation of CT is important for understanding the pathophysiological mechanisms of chlamydial disease and its transmission dynamics in sexual networks. Traditionally, strain typing of CT was based on serotyping methods characterising the major outer membrane protein (MOMP). With the advent of polymerase chain reaction and sequencing the era of molecular typing began. Molecular characterization of CT strains is based on sequence analysis of ompA gene encoding MOMP. However, in due course of time, improvements were made to enhance the discriminatory power of sequencing and quality of epidemiological information. New high-resolution genotyping methods using multiple loci such as multilocus sequence typing (MLST) and multiple loci variable number of tandem repeats (MLVA) were developed but were unable to differentiate mixed infections (MIs). The development of DNA-hybridisation methods emerged as a major breakthrough in detecting MIs. Although MLST and MLVA are more discriminative than other genotyping methods, they are laborious and expensive. DNA microarray technique is an affordable alternative for genotyping. Since recombination is widespread in the CT genome, ompA is not a reliable marker for phylogenetic studies; hence, whole genome sequencing may provide maximum phylogenetic resolution of CT strains. A descriptive review is provided of the various molecular CT typing methods. The vital information gained can be used for formulating screening programmes, targeted prevention and optimising therapeutic measures aiming to reduce disease transmission.

Prevalence of Chlamydia trachomatis Genotypes in Men Who Have Sex with Men and Men Who Have Sex with Women Using Multilocus VNTR Analysis-ompA Typing in Guangzhou, China

Background

Chlamydia trachomatis is one of the most prevalent bacterial sexually transmitted infection in China. Although C. trachomatis genotypes can be discriminated by outer membrane protein gene (ompA) sequencing, currently available methods have limited resolutions. This study used a high-resolution genotyping method, namely, multilocus variable number tandem-repeat analysis with ompA sequencing (MLVA)-ompA, to investigate the local epidemiology of C. trachomatis infections among men who have sex with men (MSM) and men who have sex with women (MSW) attending a sexually transmitted diseases (STD) clinic in Guangzhou, China.

Methods

Rectal specimens from MSM and urethral specimens from MSW were collected between January 2013 and July 2014 at the Guangdong Provincial Center STD clinic. The specimens were sent to the laboratory for analyses. All specimens that were tested positive for C. trachomatis by the commercial nucleic acid amplification tests were genotyped by MLVA-ompA.

Results

Fifty-one rectal specimens from MSM and 96 urethral specimens from MSW were identified with C. trachomatis. One hundred and forty-four of the 147 specimens were fully genotyped by MLVA-ompA. Rectal specimens from MSM were divided into four ompA genotypes and urethral specimens from MSW into nine genotypes. No mixed infections were found among all specimens. The most frequent genotypes were D, G, J, E and F. All specimens were further divided into 46 types after ompA genotyping was combined with MLVA. Genotypes D-8.7.1 and G-3.4a.3 were the most frequent among MSM, whereas genotypes D-3.4a.4, E-8.5.1, F-8.5.1, and J-3.4a.2 were the most frequent subtypes among MSW. The discriminatory index D was 0.90 for MLVA, 0.85 for ompA, and 0.95 for MLVA-ompA.

Conclusions

The most prevalent MLVA-ompA genotypes were significantly different between MSM and MSW from Guangzhou, China. Moreover, MLVA-ompA represented a more favorable degree of discrimination than ompA and could be a reliable complement for ompA for the routine subtypes of C. trachomatis.

High Frequency of Chlamydia trachomatis Mixed Infections Detected by Microarray Assay in South American Samples

Chlamydia trachomatis is one of the most common sexually transmitted infections worldwide. Based on sequence variation in the ompA gene encoding the major outer membrane protein, the genotyping scheme distinguishes 17 recognized genotypes, i.e. A, B, Ba, C, D, Da, E, F, G, H, I, Ia, J, K, L1, L2, and L3. Genotyping is an important tool for epidemiological tracking of C. trachomatis infections, including the revelation of transmission pathways and association with tissue tropism and pathogenicity. Moreover, genotyping can be useful for clinicians to establish the correct treatment when LGV strains are detected. Recently a microarray assay was described that offers several advantages, such as rapidity, ease of standardization and detection of mixed infections. The aim of this study was to evaluate the performance of the DNA microarray-based assay for C. trachomatis genotyping of clinical samples already typed by PCR-RFLP from South America. The agreement between both typing techniques was 90.05% and the overall genotype distribution obtained with both techniques was similar. Detection of mixed-genotype infections was significantly higher using the microarray assay (8.4% of cases) compared to PCR-RFLP (0.5%). Among 178 samples, the microarray assay identified 10 ompA genotypes, i.e. D, Da, E, F, G, H, I, J, K and L2. The most predominant type was genotype E, followed by D and F.

Chlamydia trachomatis infection prevalence and serovar distribution in a high-density urban area in the north of Italy

The aim of this study was to assess Chlamydia trachomatis (CT) infection prevalence and serovar distribution in a high-density urban area in the north of Italy, by comparing different groups of subjects divided on the basis of the type of care provider they referred to (STI Clinic, gynaecologists or general practitioners). From January 2011 to May 2014, all the specimens submitted to the Microbiology Laboratory of St Orsola Hospital in Bologna for CT detection were tested by PCR assay. For positive specimens, molecular genotyping based on RFLP analysis was performed. Total prevalence of CT infection was 8.1 %, with significant differences between subgroups (P<0.01) but stable during the study period. The STI Clinic was mainly responsible for CT diagnosis, whereas the lowest infection prevalence was detected in gynaecological clinics, despite the high number of tests performed. Extra-genital samples were almost exclusively collected from males at the STI Clinic. Interestingly, 13.3 % of patients providing extra-genital specimens were positive for CT on rectal and/or pharyngeal swabs, and 4.4 % of cases would have been missed if extra-genital sites had not been tested. The most common serovar was E, and serovar distribution was influenced by gender (P<0.01), age (P<0.01), care provider (P=0.01) and anatomical site (P<0.01). The L2 serovar was detected only in extra-genital samples from males at the STI Clinic. Knowledge about care providers' contributions in CT testing and diagnosis is essential for infection control. CT typing is crucial for appropriate management of specific infections, such as lymphogranuloma venereum in extra-genital samples of high-risk populations.

Emancipating Chlamydia: Advances in the Genetic Manipulation of a Recalcitrant Intracellular Pathogen

Chlamydia species infect millions of individuals worldwide and are important etiological agents of sexually transmitted disease, infertility, and blinding trachoma. Historically, the genetic intractability of this intracellular pathogen has hindered the molecular dissection of virulence factors contributing to its pathogenesis. The obligate intracellular life cycle of Chlamydia and restrictions on the use of antibiotics as selectable markers have impeded the development of molecular tools to genetically manipulate these pathogens. However, recent developments in the field have resulted in significant gains in our ability to alter the genome of Chlamydia, which will expedite the elucidation of virulence mechanisms. In this review, we discuss the challenges affecting the development of molecular genetic tools for Chlamydia and the work that laid the foundation for recent advancements in the genetic analysis of this recalcitrant pathogen.

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.

Global Multilocus Sequence Type Analysis of Chlamydia trachomatis Strains from 16 Countries

The Uppsala University Chlamydia trachomatis multilocus sequence type (MLST) database (http://mlstdb.bmc.uu.se) is based on five target regions (non-housekeeping genes) and the ompA gene. Each target has various numbers of alleles-hctB, 89; CT058, 51; CT144, 30; CT172, 38; and pbpB, 35-derived from 13 studies. Our aims were to perform an overall analysis of all C. trachomatis MLST sequence types (STs) in the database, examine STs with global spread, and evaluate the phylogenetic capability by using the five targets. A total of 415 STs were recognized from 2,089 specimens. The addition of 49 ompA gene variants created 459 profiles. ST variation and their geographical distribution were characterized using eBURST and minimum spanning tree analyses. There were 609 samples from men having sex with men (MSM), with 4 predominating STs detected in this group, comprising 63% of MSM cases. Four other STs predominated among 1,383 heterosexual cases comprising, 31% of this group. The diversity index in ocular trachoma cases was significantly lower than in sexually transmitted chlamydia infections. Predominating STs were identified in 12 available C. trachomatis whole genomes which were compared to 22 C. trachomatis full genomes without predominating STs. No specific gene in the 12 genomes with predominating STs could be linked to successful spread of certain STs. Phylogenetic analysis showed that MLST targets provide a tree similar to trees based on whole-genome analysis. The presented MLST scheme identified C. trachomatis strains with global spread. It provides a tool for epidemiological investigations and is useful for phylogenetic analyses.

No indication for tissue tropism in urogenital and anorectal Chlamydia trachomatis infections using high-resolution multilocus sequence typing

Background

Previous studies showed that C. trachomatis strains found in MSM are different from those in heterosexuals. This study investigates whether the differences in strain distribution between MSM and heterosexuals are due to tissue tropism.

Methods

C. trachomatis positive samples were collected from MSM (anorectal) and women (anorectal, cervical, vaginal, pharyngeal) visiting the STI outpatient clinic of Amsterdam between 2008 and 2013. All samples were typed using multilocus sequence typing (MLST). Epidemiological data were derived from electronic patient records.

Results

We obtained full MLST data for C. trachomatis from 207 MSM and 185 women, all with anorectal infections. Six large clusters were identified of which 3 consisted predominantly of samples from women (89%-100%), whereas the other 3 consisted predominantly of samples from MSM (97%-100%). Furthermore, we obtained full MLST data from 434 samples of 206 women with concurrent infections at multiple anatomical locations. No association was observed between C. trachomatis cluster and the anatomical location of infection.

Conclusion

We found no indication for tissue tropism in urogenital, pharyngeal and anorectal C. trachomatis infections. Combined with results from previously conducted studies, we hypothesize that MSM and heterosexuals have different distributions of C. trachomatis strains due to their separate sexual networks.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-464) contains supplementary material, which is available to authorized users.

Minimum spread of the new Swedish variant of Chlamydia trachomatis and distribution of C. trachomatis ompA genotypes in three geographically distant areas of Spain, 2011-2012

PURPOSE

The aim of this study was to determine the presence of the new Swedish Chlamydia trachomatis (C. trachomatis) variant (nvCT) and the distribution of C. trachomatis ompA genotypes in three geographically distant regions of Spain.

METHODS

The genotypes of strains causing 624 episodes of infection (January 2011-September 2012) were studied using a nested PCR that amplifies a fragment of the ompA gene, followed by sequencing. To detect nvCT, a real-time PCR was used that amplifies a fragment of the cryptic plasmid with a 377 base pair deletion, which identifies the nvCT.

RESULTS AND CONCLUSION

The ompA genotype was identified in 565 (90.5%) episodes. Eleven genotypes were detected, of which nine were found in all three regions. Only one nvCT strain was detected (0.4%), despite the predominance of genotype E (41%). Other frequent genotypes were genotypes D (19%), F (13%), G (11 %), and J (7%). Genotype L2b, causing lymphogranuloma venereum, was detected in men who have sex with men (MSM) in all three regions. Genotypes E and F were more frequent in women and heterosexual men, and genotypes D, G, J and L2b in MSM. In men, the main factor causing differences in the distribution of C. trachomatis was sexual behavior (MSM versus heterosexual men), while the distribution of C. trachomatis genotypes was similar in women and heterosexual men.

The gull (Chroicocephalus brunnicephalus) as an environmental bioindicator and reservoir for antibiotic resistance on the coastlines of the Bay of Bengal

The presence and frequency of multiresistant bacteria in wild birds act as indicators of the environmental contamination of antibiotic resistance. To explore the rate of contamination mediated by Escherichia coli, 150 fecal samples from the brown-headed gull (Chroicocephalus brunnicephalus) and 8 water samples from the Bay of Bengal area were collected, cultured, and tested for antibiotic susceptibility. Special attention was paid to extended-spectrum beta-lactamase (ESBL)-producing isolates, which were further characterized genetically. Antibiotic resistance was found in 42.3% (36/85) of the E. coli isolates and multidrug resistance in 11.8%. Isolates from the area with a higher human activity were more resistant than those from an area with a lower level of activity. Most frequent was resistance to ampicillin (29.4%), followed by trimethoprim-sulfamethoxazole (24.7%) and quinolones (22.4%). Carriage of ESBL-producing E. coli was relatively high (17.3%) in the gulls, whereas no ESBL producers were found in the water. All ESBL-producing E. coli isolates, but one, carried bla(CTX-M-15) or bla(CTX-M-15)-like genes. A bla(CTX-M-14)-like enzyme was found as an exception. Gulls from two different colonies shared E. coli clones and harbored the clinically relevant sequence types ST10, ST48, and ST131. The high frequency of antibiotic resistance and ESBL production among E. coli isolates from gulls indicates that the environmental contamination of antibiotic resistance has already gone far on the coastlines of the Bay of Bengal. Considering the limited control over the antibiotic consumption and waste from human activities in Bangladesh, there is no easy solution in sight.

Associated factors with and genotypes of Chlamydia trachomatis infection among clients seeking voluntary counseling and testing for HIV infection in Taiwan

BACKGROUND/PURPOSE

This study aimed to investigate the factors associated with Chlamydia trachomatis infection and the genotype distribution of the strains among the clients seeking voluntary counseling and testing (VCT) for human immunodeficiency virus (HIV) in Taiwan.

METHODS

The VCT clients completed an anonymous self-administered questionnaire interview to inquire into the risks for sexually transmitted diseases, followed by providing a 10-mL first-catch urine specimen to detect C. trachomatis with the use of polymerase-chain-reaction assays. The genotyping of C. trachomatis strains was performed by sequencing of omp1 gene. A case-control study was performed to identify factors associated with chlamydial infection.

RESULTS

From 2008 to 2011, 140 (4.2%) of the 3323 VCT clients tested positive for C. trachomatis by polymerase chain reaction assays of urine specimens. Compared with 280 control individuals without C. trachomatis infection, cases were more likely to be female (adjusted odds ratio, 3.28; 95% confidence interval, 1.56-6.90) and to report dysuria or urethral discharge (adjusted odds ratio, 2.57; 95% confidence interval, 1.44-4.61). Infections with genotypes Da and G were significantly more common in male than female individuals (genotype Da, 22.2% vs. 0%; and genotype G, 24.4% vs. 3.3%) and in men who have sex with men than heterosexuals (genotype Da, 22.2% vs. 0%; and genotype G, 24.4% vs. 3.3%).

CONCLUSION

Among the VCT clients in Taiwan, female sex and presence of urethral symptoms were associated with C. trachomatis infection of the genitourinary tract. Homosexual male clients were more likely to be infected with genotypes Da and G than heterosexual clients were.

Multilocus sequence typing of Chlamydia trachomatis among men who have sex with men reveals cocirculating strains not associated with specific subpopulations

BACKGROUND

Previous studies identified specific Chlamydia trachomatis strains circulating among men who have sex with men (MSM). This study investigates whether distinct C. trachomatis strains circulate among subpopulations within the MSM community.

METHODS

Participants were recruited at the sexually transmitted infection clinic of the Public Health Service of Amsterdam from 2008 to 2009. C. trachomatis samples were typed using multilocus sequence typing. Epidemiological and clinical data were derived from questionnaires and patient records.

RESULTS

Typing of 277 samples from 260 MSM identified distinct C. trachomatis strains circulating concurrently over time. Men with lymphogranuloma venereum (LGV)-inducing strains were more likely to be infected with human immunodeficiency virus, more often had a history of STI, and had a higher frequency of risky sexual behavior. No such associations were found for non-LGV-inducing strains. MSM infected with heterosexual-associated strains were often younger (P = .04) and more often reported sex with women (P = .03), compared with men infected with MSM-associated strains.

CONCLUSIONS

With the exception of LGV-inducing strains, no evidence was found that different C. trachomatis strains circulated in distinct subpopulations of MSM. This indicates that no separate transmission networks for C. trachomatis among MSM existed. However, younger MSM and bisexuals were more often infected with heterosexual-associated C. trachomatis strains.

Chlamydia trachomatis genotypes among men who have sex with men in Australia

BACKGROUND

Chlamydia trachomatis is a common bacterial sexually transmitted infection in men who have sex with men (MSM), although little is known about its distribution in Australian MSM communities.

METHODS

From 2004 to 2008, 612 consecutive C. trachomatis positive anal swab and urine samples were collected for genotyping and quantification from MSM attending 2 sexual health centers (Melbourne and Sydney).

RESULTS

The most common serovars detected were D (35.2%), G (32.7%), and J (17.7%), although these distributions changed significantly by year and city. C. trachomatis infections (2.8%) involved more than 1 serovar and only 1 lymphogranuloma venereum isolate was detected. The majority of serovar strains showed an identical omp1 genotype, with only 7.5% showing genotypic variability. Serovar G infections were not associated with overseas sexual activity; whilst individuals with serovar J were less likely to have had a prior C. trachomatis infection, and with serovar E were those who had prior C. trachomatis infection. Symptoms were present in 68% of urethral infections and 28% anal infections, and were associated with gonorrheal coinfection (13.8%), prior C. trachomatis infection (20.6%) and increasing age. A higher C. trachomatis load was identified in anal samples versus urine (1.48 × 10(4) genome copies/anal swab; 3.72 × 10(3) copies/mL urine) and no association was made to concentration including the presence of symptoms and prior C. trachomatis infection.

CONCLUSIONS

This is the largest study of C. trachomatis serovars in MSM: it is the first to report C. trachomatis rectal loads, and provides an overview on C. trachomatis serovars and genotypic variants that circulate in Australian MSM communities.

Antimicrobial drug-resistant Escherichia coli in wild birds and free-range poultry, Bangladesh

Multidrug resistance was found in 22.7% of Escherichia coli isolates from bird samples in Bangladesh; 30% produced extended-spectrum β-lactamases, including clones of CTX-M genes among wild and domestic birds. Unrestricted use of antimicrobial drugs in feed for domestic birds and the spread of resistance genes to the large bird reservoir in Bangladesh are growing problems.

Chlamydia trachomatis strains show specific clustering for men who have sex with men compared to heterosexual populations in Sweden, the Netherlands, and the United States

High-resolution genotyping of Chlamydia trachomatis improves the characterization of strains infecting different patient groups and sexual networks. In this study, multilocus sequence typing (MLST) and ompA sequence determination were used for an analysis of C. trachomatis strains from 203 men who have sex with men (MSM) from Sweden, the Netherlands, and the United States. The results obtained were compared with data from 153 heterosexual women from Sweden and the Netherlands. The overlap in MLST/ompA profiles between MSM from Sweden and the Netherlands was 68%, while the overlap between heterosexual populations from these countries was only 18%. The distribution of genotypes in MSM from the United States was less similar to that in MSM from the European countries, with 45% and 46% overlaps for MSM in Sweden and the Netherlands, respectively. Minimum-spanning-tree analysis of MLST/ompA sequence types identified two large clusters that contained almost exclusively samples from MSM and comprised 74% of all MSM samples. Three other clusters were predominated by samples from women but also contained MSM specimens. Of 19 detected variants of the MLST target CT144, three variants were highly associated with MSM. Our study supports the hypotheses of both tissue tropism as well as epidemiological network structures as explanations for the linkage between specific genetic variants and sexual orientation.

Population genomics of Chlamydia trachomatis: insights on drift, selection, recombination, and population structure

The large number of sexually transmitted diseases and ocular trachoma cases that are caused globally each year by Chlamydia trachomatis has made this organism a World Health Organization priority for vaccine development. However, there is no gene transfer system for Chlamydia to help identify potential vaccine targets. To accelerate discoveries toward this goal, here we analyzed the broadest diversity of C. trachomatis genomes to date, including 25 geographically dispersed clinical and seven reference strains representing 14 of the 19 known serotypes. Strikingly, all 32 genomes were found to have evidence of DNA acquisition by homologous recombination in their history. Four distinct clades were identified, which correspond to all C. trachomatis disease phenotypes: lymphogranuloma venereum (LGV; Clade 1); noninvasive urogenital infections (Clade 2); ocular trachoma (Clade 3); and protocolitis (Clade 4; also includes some noninvasive urogenital infections). Although the ancestral relationship between clades varied, most strains acted as donor and recipient of recombination with no evidence for barriers to genetic exchange. The niche-specific LGV and trachoma clades have undergone less recombination, although the opportunity for mixing with strains from other clades that infect the rectal and ocular mucosa, respectively, is evident. Furthermore, there are numerous occasions for gene conversion events through sequential infections at the same anatomic sites. The size of recombinant segments is relatively small (~357 bp) compared with in vitro experiments of various C. trachomatis strains but is consistent with in vitro estimates for other bacterial species including Escherichia coli and Helicobacter pylori. Selection has also played a crucial role during the diversification of the organism. Clade 2 had the lowest nonsynonymous to synonymous ratio (dN/dS) but the highest effect of recombination, which is consistent with the widespread occurrence of synonymous substitutions in recombined genomic segments. The trachoma Clade 3 had the highest dN/dS estimates, which may be caused by an increased effect of genetic drift from niche specialization and a reduced effective population size. The degree of drift, selection, and recombination in C. trachomatis suggests that the challenge will remain to identify genomic regions that are stable and cross protective for the development of an efficacious vaccine.

Distribution of Chlamydia trachomatis serotypes in clinical urogenital samples from north-eastern Croatia

The purpose of this study was to determine prevalence of Chlamydia trachomatis (Ct) urogenital infection and its serotype distribution from clinical samples in north-eastern Croatia. During a 3-year period, 2,379 urogenital samples were analyzed by real-time polymerase chain reaction (A group), while 4,846 genital swabs were analyzed by direct fluorescent antibody test (B group). 132 Ct positive specimens were genotyped by omp1 gene sequencing. The prevalence rate of Ct was 3.2 % in A and 1 % in B group. The most prevalent chlamydial genotype was E (44 %), followed by F (33 %), K (11.5 %), G (8 %), J/UW (5.3 %), D-IC (4.4 %), D-B120 (1.8 %), and B/IU, J/IU, Ia/IU (0.9 % each) serotypes. Single-nucleotide polymorphisms (SNPs) of omp1 gene were detected in E, K, and G serotypes. Some of these SNPs (C/T at position 272 and G/A at position 813 in E strain; C/T at position 884 in D strain) might represent novel omp1 variants.

Phenotypic and genetic characterisation of bacterial sexually transmitted infections in Bissau, Guinea-Bissau, West Africa: a prospective cohort study

BACKGROUND

Knowledge regarding characteristics and transmission of Neisseria gonorrhoeae, Chlamydia trachomatis and Mycoplasma genitalium and antibiotic resistance in N gonorrhoeae in Guinea-Bissau, West Africa, is entirely lacking.

OBJECTIVES

To characterise N gonorrhoeae, C trachomatis and M genitalium samples from Guinea-Bissau and to define bacterial populations, possible transmission chains and for N gonorrhoeae spread of antibiotic-resistant isolates.

DESIGN

Prospective cohort study.

SETTING

Two sexual health and family planning clinics, Bissau, Guinea-Bissau.

PARTICIPANTS

Positive samples from 711 women and 27 men.

MATERIAL AND METHODS

Positive samples for N gonorrhoeae (n=31), C trachomatis (n=60) and M genitalium (n=30) were examined. The gonococcal isolates were characterised with antibiograms, serovar determination and N gonorrhoeae multiantigen sequence typing (NG-MAST). The C trachomatis ompA gene and the M genitalium mgpB gene were sequenced, and phylogenetic analyses were performed.

RESULTS

For N gonorrhoeae, the levels of resistance (intermediate susceptibility) to ciprofloxacin, erythromycin, rifampicin, ampicillin, tetracycline, penicillin G and cefuroxime were 10% (0%), 6% (10%), 13% (10%), 68% (0%), 74% (0%), 68% (16%) and 0% (84%), respectively. All isolates were susceptible to cefixime, ceftriaxone, spectinomycin and azithromycin, and the minimum inhibitory concentrations of kanamycin (range: 8-32 mg/l) and gentamicin (range: 0.75-6 mg/l) were low (no resistance breakpoints exist for these antimicrobials). 19 NG-MAST sequence types (STs) (84% novel STs) were identified. Phylogenetic analysis of the C trachomatis ompA gene revealed genovar G as most prevalent (37%), followed by genovar D (19%). 23 mgpB STs were found among the M genitalium isolates, and 67% of isolates had unique STs.

CONCLUSIONS

The diversity among the sexually transmitted infection (STI) pathogens may be associated with suboptimal diagnostics, contact tracing, case reporting and epidemiological surveillance. In Guinea-Bissau, additional STI studies are vital to estimate the STI burden and form the basis for a national sexual health strategy for prevention, diagnosis and surveillance of STIs.

Development of the molecular typing protocol for C. Trachomatis based on the sequencing of ompa,pbpb, ct046, ct058, ct144, ct172 genes

The article is devoted to the development and validation of a standard operating procedure entitled «Molecular typing of С. trachomatis for assessment of the clonal structure and extent of genetic diversity of С. trachomatis strains circulating in the territory of the Russian Federation.» The studies that involved the typing of C. trachomatis strains obtained from regions of the Russian Federation with the use of six c. trachomatis genes (ompA, СТ046, cT058, cT144, cT172 and pbpB) revealed their significant heterogenicity with the prevalence of the E serotype. However, the typing of c. trachomatis for six genes at one time seems to be too time-consuming and long-lasting and is hard to be interpreted, which explains the need to develop other typing protocols using a smaller number of relevant genes (not more than two or three - by analogy with NG-MAST).

Hypervirulent Chlamydia trachomatis clinical strain is a recombinant between lymphogranuloma venereum (L(2)) and D lineages

Chlamydia trachomatis is an obligate intracellular bacterium that causes a diversity of severe and debilitating diseases worldwide. Sporadic and ongoing outbreaks of lymphogranuloma venereum (LGV) strains among men who have sex with men (MSM) support the need for research on virulence factors associated with these organisms. Previous analyses have been limited to single genes or genomes of laboratory-adapted reference strain L₂/434 and outbreak strain L₂b/UCH-1/proctitis. We characterized an unusual LGV strain, termed L₂c, isolated from an MSM with severe hemorrhagic proctitis. L₂c developed nonfusing, grape-like inclusions and a cytotoxic phenotype in culture, unlike the LGV strains described to date. Deep genome sequencing revealed that L₂c was a recombinant of L₂ and D strains with conserved clustered regions of genetic exchange, including a 78-kb region and a partial, yet functional, toxin gene that was lost with prolonged culture. Indels (insertions/deletions) were discovered in an ftsK gene promoter and in the tarp and hctB genes, which encode key proteins involved in replication, inclusion formation, and histone H1-like protein activity, respectively. Analyses suggest that these indels affect gene and/or protein function, supporting the in vitro and disease phenotypes. While recombination has been known to occur for C. trachomatis based on gene sequence analyses, we provide the first whole-genome evidence for recombination between a virulent, invasive LGV strain and a noninvasive common urogenital strain. Given the lack of a genetic system for producing stable C. trachomatis mutants, identifying naturally occurring recombinants can clarify gene function and provide opportunities for discovering avenues for genomic manipulation.

Lymphogranuloma venereum (LGV) is a prevalent and debilitating sexually transmitted disease in developing countries, although there are significant ongoing outbreaks in Australia, Europe, and the United States among men who have sex with men (MSM). Relatively little is known about LGV virulence factors, and only two LGV genomes have been sequenced to date. We isolated an LGV strain from an MSM with severe hemorrhagic proctitis that was morphologically unique in tissue culture compared with other LGV strains. Bioinformatic and statistical analyses identified the strain as a recombinant of L₂ and D strains with highly conserved clustered regions of genetic exchange. The unique culture morphology and, more importantly, disease phenotype could be traced to the genes involved in recombination. The findings have implications for bacterial species evolution and, in the case of ongoing LGV outbreaks, suggest that recombination is a mechanism for strain emergence that results in significant disease pathology.

Anal infections with concomitant Chlamydia trachomatis genotypes among men who have sex with men in Amsterdam, the Netherlands

Background

Lymphogranuloma venereum (LGV) proctitis is caused by Chlamydia trachomatis (Ct) genotype L and is endemic among men who have sex with men (MSM) in western society. Genotype L infections need to be distinguished from non-LGV (genotypes A-K) Ct infections since they require prolonged antibiotic treatment. For this purpose, an in-house developed pmpH based LGV polymerase chain reaction (PCR) test is used at the Amsterdam STI outpatient clinic. We investigated retrospectively the anal Ct genotype distribution, and the frequency of concomitant genotype infections in MSM infected with LGV and non-LGV Ct infections. To detect concomitant Ct genotype infections, the pmpH LGV PCR and genoTyping Reverse Hybridization Assay (Ct-DT RHA) were used.

Methods

A total of 201 Ct positive rectal swabs from MSM were selected, which were previously diagnosed as either LGV (n = 99) or non-LGV Ct infection (n = 102) according to the algorithm of Ct detection by the commercially available Aptima Combo 2 assay followed by an in-house pmpH LGV PCR. The samples were retested with the commercially available Ct-DT RHA, which differentiates between 14 major genotypes and is able to detect concomitant Ct genotypes.

Results

Excellent genotyping agreement was observed between the Ct-DT RHA and the pmpH LGV PCR (Kappa = 0.900, 95%CI = 0.845-0.955, McNemar's p = 1.000). A concomitant non-LGV genotype was detected in 6/99 (6.1%) LGV samples. No additional LGV infections were observed with the Ct-DT RHA among the non-LGV Ct group. In the non-LGV group genotype G/Ga (34.3%) was seen most frequent, followed by genotype D/Da (22.5%) and genotype J (13.7%). All LGV infections were caused by genotype L2.

Conclusions

Concomitant non-LGV genotypes do not lead to missed LGV proctitis diagnosis. The pmpH LGV PCR displayed excellent agreement with the commercially available Ct-DT genotyping RHA test. The genotypes G/Ga, D/Da and J were the most frequent non-LGV Ct strains in MSM.

Typing of lymphogranuloma venereum Chlamydia trachomatis strains

We analyzed by multilocus sequence typing 77 lymphogranuloma venereum Chlamydia trachomatis strains from men who have sex with men in Europe and the United States. Specimens from an outbreak in 2003 in Europe were monoclonal. In contrast, several strains were in the United States in the 1980s, including a variant from Europe.

Genotyping of Chlamydia trachomatis strains from culture and clinical samples using an ompA-based DNA microarray assay

Current typing methods of Chlamydia (C.) trachomatis are mainly based on the diversity of the ompA gene, which is coding for the major outer membrane protein A. The present study aimed at facilitating genotyping of strains of this obligate intracellular human pathogen by developing a DNA microarray assay using the ArrayTube™ format for individual samples and the ArrayStrip™ format for higher throughput. The new test is exploiting multiple discriminatory sites by involving a total of 61 oligonucleotide probes representing genotype-specific polymorphisms in variable domains 1, 2 and 4 of the ompA gene. After multiplex amplification of these domains using biotinylated primers, the sample is hybridized in the microarray vessel under highly stringent conditions. The resulting binding pattern is genotype specific, thus allowing direct identification. We were able to show that DNA from each of the currently accepted genotypes (serovars) yielded a unique, theoretically expected and distinct hybridization pattern. The assay was also shown to be highly sensitive as a dilution containing the equivalent of 1 inclusion-forming unit was still correctly genotyped. In addition, when 62 clinical samples were examined and compared to PCR-RFLP typing results, the genotype was correctly identified by the DNA microarray in all cases. The present test is easy to handle and economically affordable, and it allows genotyping of C. trachomatis to be accomplished within a working day, thus lending itself for epidemiological studies and routine diagnosis.

Methods for typing std pathogens (N. Gonorrhoeae, C. Trachomatis, T. Pallidum)

Phenotypic methods were initially used for bacterial typing yet they have a number of drawbacks limiting their use. Methods of molecular and genetic typing have become wide-spread today. Among these methods, bacterial typing based on multilocus sequence typing (Multilocus Sequence Typing - MLST) has been developing at the fastest rate. However, schemes of molecular and genetic typing of STD pathogens as compared to other bacteria are insufficiently developed, which considerably complicates the planning of measures aimed at the reduction of their spread.

Lymphogranuloma venereum proctocolitis: a silent endemic disease in men who have sex with men in industrialised countries

Lymphogranuloma venereum (LGV) is a sexually transmitted disease (STD) caused by serovars L1-L3 of Chlamydia trachomatis. Rare in the western world prior to 2003, different outbreaks or clusters of LGV have been reported in Europe, North America and Australia among men who have sex with men (MSM) over the past few years. The majority were HIV infected MSM with high-risk sexual behaviour and a high rate of concomitant STD, including hepatitis C. Most of them presented with a proctitis syndrome and only a few with the classical bubonic form. A previously non-described serovar, L2b, has been identified as the main causative agent of the epidemic. A delay in diagnosis has been the rule because of the misleading symptomatology of LGV proctitis, the unfamiliarity of the disease to physicians, and the lack of a routine diagnostic test for LGV serovars. It is crucial to increase the awareness of the disease among physicians for prompt diagnosis and treatment, to avoid complications, and to stop ongoing transmission. It has additional public health implications since LGV may facilitate the transmission and acquisition of HIV and other STD.

Chlamydial infection of monocytes stimulates IL-1beta secretion through activation of the NLRP3 inflammasome

Chlamydia trachomatis infections represent the leading cause of bacterial sexually-transmitted disease in the United States and can cause serious tissue damage leading to infertility and ectopic pregnancies in women. Inflammation and hence the innate immune response to chlamydial infection contributes significantly to tissue damage, particularly by secreting proinflammatory cytokines such as interleukin (IL)-1beta from monocytes, macrophages and dendritic cells. Here we demonstrate that C. trachomatis or Chlamydia muridarum infection of a monocytic cell line leads to caspase-1 activation and IL-1beta secretion through a process requiring the NLRP3 inflammasome. Thus, secretion of IL-1beta decreased significantly when cells were depleted of NLRP3 or treated with the anti-inflammatory inhibitors parthenolide or Bay 11-7082, which inhibit inflammasomes and the transcription factor NF-kappaB. As for other infections causing NRLP3 inflammasome assembly, caspase-1 activation in monocytes is triggered by potassium efflux and reactive oxygen species production. However, anti-oxidants inhibited IL-1beta secretion only partially. Atypically for a bacterial infection, caspase-1 activation during chlamydial infection also involves partially the spleen tyrosine kinase (Syk), which is usually associated with a pathogen recognition receptor for fungal pathogens. Secretion of IL-1beta during infection by many bacteria requires both microbial products from the pathogen and an exogenous danger signal, but chlamydial infection provides both the pathogen-associated molecular patterns and danger signals necessary for IL-1beta synthesis and its secretion from human monocytes. Use of inhibitors that target the inflammasome in animals should therefore dampen inflammation during chlamydial infection.

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.

Lymphogranuloma venereum in Portugal: unusual events and new variants during 2007

BACKGROUND

Several European countries identified an ongoing LGV outbreak, particularly among men who have sex with men (MSM). In Portugal, no particular surveillance measures were launched. Nonetheless, circulating LGV strains could eventually be detected through the routine Chlamydia trachomatis ompA genotyping procedure held in the Portuguese National Institute of Health (NIH).

METHODS

During 2007, 178 Chlamydia trachomatis specimens were genotyped through amplification and automated-sequencing of ompA. Sequences of 891bp (nt142-nt1032) were aligned with currently available chlamydial sequences from GenBank to identify the corresponding genotype.

RESULTS

Eight Chlamydia trachomatis specimens matched LGV-genotypes (7 "L2" and 1 mixed E+L2 undetermined variant). These specimens were identified in samples collected from 4 women and 4 men. One HIV(+) MSM presented LGV related symptoms, while the other infected persons were either asymptomatic or presented no clear LGV symptoms. All samples revealed ompA sequences different from the L2/434 reference strain and from the L2b/144276, which is the most frequently described genotype during the recent LGV outbreak.

CONCLUSIONS

The detection of 7 LGV specimens during 2007 in contrast with their absence over the previous 5 years. The LGV infected individuals do not seem to be related to any sexual networks of MSM, contrarily to those described in other European countries. Moreover, all Lisbon LGV specimens revealed unusual ompA sequences that differentiate them from the currently reported LGV infections in Europe. The results of the current study further justify an attentive surveillance of LGV strains infecting different populations and the study of their relation with clinical aspects and disease patterns.

Chlamydia trachomatis serovar distribution and other concurrent sexually transmitted infections in heterosexual men with urethritis in Italy

The distribution of Chlamydia trachomatis serovars among 157 heterosexual male patients with urethritis and the presence of coinfections with other sexually transmitted infections were studied. One hundred seventeen (74.5%) patients, with a mean age of 33.7 years, were Italians, whereas 40 (25.5%) were immigrants coming from eastern European countries, Africa, and South America. All the immigrants and 82 (70.0%) Italian patients reported sex with prostitutes. Out of 157 patients, 73 (46.5%) were found positive for C. trachomatis in urethral secretions and eight different C. trachomatis serovars were identified. The most common serovars were E (n = 18; 24.7%), D (n = 15; 20.5%), G (n = 14;19.2%), and F (n = 12; 16.4%). The sequencing data showed a high degree of conservation of the omp1 gene. Thirty-six (46.7%) out of the 73 C. trachomatis-positive patients were coinfected with another sexually transmitted infection. The most common coinfection was gonorrhoea detected in 22 (30.1%) patients, followed by condyloma in eight (8.2%) patients, syphilis in five (6.8%), and HIV in three (4.1%).

Development of real-time PCR assays for genotyping of Chlamydia trachomatis

We have developed and validated a nested real-time PCR (NRT-PCR) for the genotyping of Chlamydia trachomatis and used it specifically for the typing of either eight genovars from D to K or three genovars of lymphogranuloma venereum (LGV). The 11 probes used in the NRT-PCR correctly identified the DNA from D to K and LGV reference strains and did not cross-react with the DNA from 26 strains representing the bacterial pathogens and commensals of the oropharynx, genital tract, and rectum. The NRT-PCR had a 95% probability of detection at four genome copies (confidence interval, three to six copies) of C. trachomatis per reaction. One hundred cervical and urethral swab specimens containing C. trachomatis DNA from 63 women and 37 men were used to validate the method. The results from the NRT-PCR and the DNA sequencing of amplicons generated from the omp1 gene showed 100% correlation for these samples. The assay also identified the LGV-II genotype in 24 of 48 rectal swab specimens containing C. trachomatis DNA that were obtained from men having sex with men. The Sexually Transmitted Bacteria Reference Laboratory, London, independently confirmed these results using group-specific LGV real-time PCR and restriction fragment length polymorphism analysis. Compared with the NRT-PCR, non-NRT-PCR was found to be less sensitive: it typed C. trachomatis DNA in only 80% of the genital samples and 90% of the rectal swab samples. This is the first successful demonstration of the use of real-time PCR for the genotype-specific typing of C. trachomatis strains that cause sexually transmitted diseases.

High-resolution genotyping of Chlamydia trachomatis strains by multilocus sequence analysis

Genotyping of Chlamydia trachomatis is limited by the low sequence variation in the genome, and no adequate method is available for analysis of the spread of chlamydial infections in the community. We have developed a multilocus sequence typing (MLST) system based on five target regions and compared it with analysis of ompA, the single gene most extensively used for genotyping. Sequence determination of 16 reference strains, comprising all major serotypes, serotypes A to L3, showed that the number of genetic variants in the five separate target regions ranged from 8 to 16. The genetic variation in 47 clinical C. trachomatis isolates of representative serotypes (14 serotype D, 12 serotype E, 11 serotype G, and 10 serotype K strains) was analyzed; and the MLST system detected 32 variants, whereas 12 variants were detected by using ompA analysis. Specimens of the predominant serotype, serotype E, were differentiated into seven genotypes by MLST but into only two by ompA analysis. The MLST system was applied to C. trachomatis specimens from a population of men who have sex with men and was able to differentiate 10 specimens of one predominant ompA genotype G variant into four distinct MLST variants. To conclude, our MLST system can be used to discriminate C. trachomatis strains and can be applied to high-resolution molecular epidemiology.