Genotype-Specific Concordance of Chlamydia trachomatis Genital Infection Within Heterosexual Partnerships

Sexual transmission of urogenital bacteria: whole metagenome sequencing evidence from a sexual network study

Sexual transmission of the urogenital microbiota may contribute to adverse sexual and reproductive health outcomes. The extent of sexual transmission of the urogenital microbiota is unclear as prior studies largely investigated specific pathogens. We used epidemiologic data and whole metagenome sequencing to characterize urogenital microbiota strain concordance between participants of a sexual network study. Individuals who screened positive for genital Chlamydia trachomatis were enrolled and referred their sexual contacts from the prior 60-180 days. Snowball recruitment of sexual contacts continued for up to four waves. Vaginal swabs and penile urethral swabs were collected for whole metagenome sequencing. We evaluated bacterial strain concordance using inStrain and network analysis. We defined concordance as ≥99.99% average nucleotide identity over ≥50% shared coverage; we defined putative sexual transmission as concordance between sexual contacts with <5 single-nucleotide polymorphisms per megabase. Of 138 participants, 74 (54%) were female; 120 (87%) had genital chlamydia; and 43 (31%) were recruited contacts. We identified 115 strain-concordance events among 54 participants representing 25 bacterial species. Seven events (6%) were between sexual contacts including putative heterosexual transmission of Fannyhessea vaginae, Gardnerella leopoldii, Prevotella amnii, Sneathia sanguinegens, and Sneathia vaginalis (one strain each), and putative sexual transmission of Lactobacillus iners between female contacts. Most concordance events (108, 94%) were between non-contacts, including eight female participants connected through 18 Lactobacillus crispatus and 3 Lactobacillus jensenii concordant strains, and 14 female and 2 male participants densely interconnected through 52 Gardnerella swidsinskii concordance events.IMPORTANCEEpidemiologic evidence consistently indicates bacterial vaginosis (BV) is sexually associated and may be sexually transmitted, though sexual transmission remains subject to debate. This study is not capable of demonstrating BV sexual transmission; however, we do provide strain-level metagenomic evidence that strongly supports heterosexual transmission of BV-associated species. These findings strengthen the evidence base that supports ongoing investigations of concurrent male partner treatment for reducing BV recurrence. Our data suggest that measuring the impact of male partner treatment on F. vaginae, G. leopoldii, P. amnii, S. sanguinegens, and S. vaginalis may provide insight into why a regimen does or does not perform well. We also observed a high degree of strain concordance between non-sexual-contact female participants. We posit that this may reflect limited dispersal capacity of vaginal bacteria coupled with individuals' comembership in regional transmission networks where transmission may occur between parent and child at birth, cohabiting individuals, or sexual contacts.

Association of Chlamydia trachomatis burden with the vaginal microbiota, bacterial vaginosis, and metronidazole treatment

Bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is a common coinfection with Chlamydia trachomatis (Ct), and BV-associated bacteria (BVAB) and their products have been implicated in aiding Ct evade natural immunity. Here, we determined if a non-optimal vaginal microbiota was associated with a higher genital Ct burden and if metronidazole, a standard treatment for BV, would reduce Ct burden or aid in natural clearance of Ct infection. Cervicovaginal samples were collected from women at enrollment and, if testing positive for Ct infection, at a follow-up visit approximately one week later. Cervical Ct burden was assessed by inclusion forming units (IFU) and Ct genome copy number (GCN), and 16S rRNA gene sequencing was used to determine the composition of the vaginal microbiota. We observed a six-log spectrum of IFU and an eight-log spectrum of GCN in our study participants at their enrollment visit, but BV, as indicated by Amsel's criteria, Nugent scoring, or VALENCIA community state typing, did not predict infectious and total Ct burden, although IFU : GCN increased with Amsel and Nugent scores and in BV-like community state types. Ct burden was, however, associated with the abundance of bacterial species in the vaginal microbiota, negatively with Lactobacillus crispatus and positively with Prevotella bivia. Women diagnosed with BV were treated with metronidazole, and Ct burden was significantly reduced in those who resolved BV with treatment. A subset of women naturally cleared Ct infection in the interim, typified by low Ct burden at enrollment and resolution of BV. Abundance of many BVAB decreased, and Lactobacillus increased, in response to metronidazole treatment, but no changes in abundances of specific vaginal bacteria were unique to women who spontaneously cleared Ct infection.

When Bacteria and Viruses Collide: A Tale of Chlamydia trachomatis and Sexually Transmitted Viruses

The global incidence of sexually transmitted infections (STIs) remains high, with the World Health Organization (WHO) estimating that over 1 million people acquire STIs daily. STIs can lead to infertility, pregnancy complications, and cancers. Co-infections with multiple pathogens are prevalent among individuals with an STI and can lead to heightened infectivity and more severe clinical manifestations. Chlamydia trachomatis (CT) is the most reported bacterial STI worldwide in both men and women, and several studies have demonstrated co-infection of CT with viral and other bacterial STIs. CT is a gram-negative bacterium with a unique biphasic developmental cycle including infectious extracellular elementary bodies (EBs) and metabolically active intracellular reticulate bodies (RBs). The intracellular form of this organism, RBs, has evolved mechanisms to persist for long periods within host epithelial cells in a viable but non-cultivable state. The co-infections of CT with the most frequently reported sexually transmitted viruses: human immunodeficiency virus (HIV), human papillomavirus (HPV), and herpes simplex virus (HSV) have been investigated through in vitro and in vivo studies. These research studies have made significant strides in unraveling the intricate interactions between CT, these viral STIs, and their eukaryotic host. In this review, we present an overview of the epidemiology of these co-infections, while specifically delineating the underlying mechanisms by which CT influences the transmission and infection dynamics of HIV and HSV. Furthermore, we explore the intricate relationship between CT and HPV infection, with a particular emphasis on the heightened risk of cervical cancer. By consolidating the current body of knowledge, we provide valuable insights into the complex dynamics and implications of co-infection involving CT and sexually transmitted viruses.

Neisseria gonorrhoeae Infection in Women Increases With Rising Gonococcal Burdens in Partners: Chlamydia Coinfection in Women Increases Gonococcal Burden

BACKGROUND

Likelihood of Neisseria gonorrhoeae infection in women exposed to male sex partners with increasing N. gonorrhoeae burdens and enhancement by Chlamydia trachomatis is not defined.

METHODS

We identified men with urethritis and their regular female sex partners. Exposure to N. gonorrhoeae burdens in men was compared in N. gonorrhoeae-infected versus -uninfected partners. Association of N. gonorrhoeae infection in women with burdens in male partners was estimated using logistic regression. Association of C. trachomatis coinfection and N. gonorrhoeae burdens in women adjusted for burdens in male partners was estimated by linear regression.

RESULTS

In total, 1816 men were enrolled; 202 had ≥2 partners, 91 who confirmed monogamy and were enrolled; 77% were married. Seventy were partners of N. gonorrhoeae-infected men; 58 (83%) were N. gonorrhoeae infected, 26 (45%) C. trachomatis coinfected. Infected women had partners with 9.3-fold higher N. gonorrhoeae burdens than partners of uninfected women (P = .0041). Association of N. gonorrhoeae infection in women with upper quartiles of N. gonorrhoeae burdens in partners increased (odds ratios ≥ 2.97)compared to the first quartile (P = .032). N. gonorrhoeae burdens in C. trachomatis-coinfected women were 2.82-fold higher than in C. trachomatis-uninfected women (P = .036).

CONCLUSIONS

N. gonorrhoeae infections increased in women whose partners were infected with higher N. gonorrhoeae burdens. C. trachomatis coinfection was associated with increased N. gonorrhoeae burdens in women.

The association between adverse pregnancy outcomes with genital Chlamydia Trachomatis infection among pre-pregnancy couples in Shenzhen, China: A cross-sectional study

Objectives

To investigate the prevalence of adverse pregnancy outcomes (APOs) in women and the impact of pre-pregnancy couples' genital Chlamydia Trachomatis (GCT) infection and other infections on APOs.

Study design

Data on genital infections were collected from the Free Pre-pregnancy Health Check (FPHC) in Shenzhen, China. Data on APOs were collected from a 1-year telephone follow-up of pregnancy status and subsequent pregnancy outcomes.

Methods

APO data were used to count adverse outcomes, and logistic regression was conducted to determine the association between APOs and GCT infection.

Results

From December 2018 to December 2019, among 4,429 couples who underwent FPHC; 1,925 were pregnant, and 1,816 couples were tracked for pregnancy outcomes, including 1,471 normal pregnancies and 345 (19.00%) APOs. The rest of 109 pregnant couples did not answer the phone or refused to answer the pregnancy outcome during the follow-up. Among APOs, the number of spontaneous abortions was 122 (35.36%), the number of macrosomia was 85 (24.64%), the number of low birth weight (LBW) & preterm births (PTB) was 39 (11.30%), the number of LBW was 34 (9.86%), and the number of PTB was 31 (8.99%). The prevalence of GCT infection in females and males was 4.24% [95% Confidence Interval, (CI): 3.41-5.27%] and 3.58% (95% CI: 2.79-4.57%), respectively. More than half (52.69%, 49/93) of the couples were GCT-concordant. The prevalence of APOs in couples without GCT infection was 18.74% (332/1,772). The prevalence of APOs in female GCT-discordant was 32.14% (9/28), and the prevalence of APOs in male GCT-discordant was 25% (4/16). The prevalence of APOs in GCT-concordant was 12.24% (6/49). Multivariable analysis indicated that females 30-35 years old [adjusted Odds Ratio (aOR) = 1.08, 95% CI: 1.01-1.17] and over 35 years old (aOR = 1.16, 95% CI: 1.03-1.32) were more likely to experiencing APOs.

Conclusion

Although only women's age was found to be associated with APOs, the prevalence of APOs with GCT-discordant in couples, especially female GCT-discordant, was higher than in those without infection or who were GCT-concordant, suggesting that these groups, especially in older women, should be paid more attention to in follow-ups to improve reproductive health.

Chlamydia trachomatis Infection and Seropositivity in Women Reporting Sexual Contact to a Chlamydia-Infected Partner

ABSTRACT

Among 73 women presenting to a sexually transmitted infection (STI) clinic in Birmingham, Alabama for reported sexual contact to a chlamydia-infected partner, Chlamydia trachomatis was detected in genital specimens in 24 (32.8%), less often in women reporting prior chlamydial infection ( P = 0.001). Most women (93.2%) were C. trachomatis seropositive.

Chlamydia trachomatis as a Current Health Problem: Challenges and Opportunities

Chlamydia is one of the most common sexually transmitted bacterial infections (STIs) worldwide. It is caused by Chlamydia trachomatis (CT), which is an obligate intracellular bacterium. In some cases, it can occur in coinfection with other parasites, increasing the pathologic potential of the infection. The treatment is based on antibiotic prescription; notwithstanding, the infection is mostly asymptomatic, which increases the risk of transmission. Therefore, some countries have implemented Chlamydia Screening Programs in order to detect undiagnosed infections. However, in Portugal, there is no CT screening plan within the National Health Service. There is no awareness in the general healthcare about the true magnitude of this issue because most of the methods used are not Nucleic Acid Amplification Technology-based and, therefore, lack sensitivity, resulting in underreporting infection cases. CT infections are also associated with possible long-term severe injuries. In detail, persistent infection triggers an inflammatory milieu and can be related to severe sequels, such as infertility. This infection could also trigger gynecologic tumors in women, evidencing the urgent need for cost-effective screening programs worldwide in order to detect and treat these individuals adequately. In this review, we have focused on the success of an implemented screening program that has been reported in the literature, the efforts made concerning the vaccine discovery, and what is known regarding CT infection. This review supports the need for further fundamental studies in this area in order to eradicate this infection and we also suggest the implementation of a Chlamydia Screening Program in Portugal.

Controversies and evidence on Chlamydia testing and treatment in asymptomatic women and men who have sex with men: a narrative review

Background

Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection (STI) worldwide. CT is mainly asymptomatic. Test-and-treat strategies are widely implemented to prevent transmission and complications. Strategies are not without controversy in asymptomatic women and men who have sex with men (MSM). Concerns are emerging to test and treat asymptomatic persons for urogenital CT (‘Controversy 1’) and pharyngeal or rectal CT (‘Controversy 2’), whereby testing symptomatic persons is not under debate. Opposed views in CT treatment involve using azithromycin versus doxycycline (‘Controversy 3’). The objective of this review is to provide coverage of these public health and clinical controversies by reviewing the current scientific evidence.

Methods

A literature search was performed using PubMed for relevant publications between 2018 and September 2021, and iterative retrieval of additional relevant publications.

Results

Controversy 1. In women, the majority of asymptomatic CT are at the urogenital site, and detections mostly include viable CT. CT easily transmits to a partner and potentially also between the vaginal and rectal areas; the clinical impact of urogenital CT is established, although risks for adverse outcomes are uncertain. Wide-scale testing in asymptomatic women has not resulted in reduced prevalence. In MSM, evidence for the clinical impact of asymptomatic urogenital CT is lacking. Controversy 2. Rectal CT is common in women diagnosed with urogenital CT, but the clinical impact of asymptomatic rectal CT is uncertain. In MSM, rectal CT is common, and most CT infections are at the rectal site, yet the risk of longer term complications is unknown. In both sexes, pharyngeal CT is uncommon and has no documented clinical impact. Controversy 3. In the treatment of rectal CT, doxycycline has superior effectiveness to azithromycin. Evidence has also accumulated on the harms of test-and-treat strategies.

Conclusions

Current practices vary widely, from widescale test-and-treat approaches to more individual patient- and partner-level case management. Choosing which asymptomatic people to test at what anatomic site, and whether to test or not, requires an urgent (re-)definition of the goals of testing and treating asymptomatic persons. Treatment guidelines are shifting toward universal doxycycline use, and clinical practice now faces the challenge of implementation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07171-2.

Test-and-treat is a key strategy in the control of Chlamydia trachomatis (CT). We discuss recent controversies and present scientific evidence regarding urogenital, rectal, and pharyngeal CT test-and-treat strategies in women and in men who have sex with men (MSM). This should inform best practices for the prevention and management of the most common bacterial sexually transmitted infection (STI) worldwide.

Reduced Endometrial Ascension and Enhanced Reinfection Associated with IgG Antibodies to Specific Chlamydia trachomatis Proteins in Women at Risk for Chlamydia

BACKGROUND

Previous research revealed antibodies targeting Chlamydia trachomatis (CT) elementary bodies was not associated with reduced endometrial or incident infection in CT-exposed women. However, data on the role of CT protein-specific antibodies in protection are limited.

METHODS

A whole-proteome CT array screening serum pools from CT-exposed women identified 121 immunoprevalent proteins. Individual sera were probed using a focused array. IgG antibody frequencies and endometrial or incident infection relationships were examined using Wilcoxon Rank sum test. The impact of breadth and magnitude of protein-specific IgGs on ascension and incident infection were examined using multivariable stepwise logistic regression. Complementary RNA-sequencing quantified CT gene transcripts in cervical swabs from infected women.

RESULTS

IgG to Pgp3 and CT005 were associated with reduced endometrial infection; anti-CT443, -CT486 and -CT123 were associated with increased incident infection. Increased breadth of protein recognition did not however predict protection from endometrial or incident infection. mRNAs for immunoprevalent CT proteins were highly abundant in the cervix.

CONCLUSIONS

Protein-specific CT antibodies are not sufficient to protect against ascending or incident infection but broad recognition of CT proteins by IgG correlates with cervical CT gene transcript abundance, suggesting CT protein abundance correlates with immunogenicity and signifies their potential as vaccine candidates.

Prevalence, concordance and reproductive sequelae after Chlamydia trachomatis infection in Mexican infertile couples

There are few concordance studies on the Chlamydia trachomatis (infection among infertile couples. The objective of this research was to know the prevalence, concordance and reproductive sequelae that couples may develop when both partners show a C. trachomatis infection. A cross-sectional study among 688 infertile couples using the C. trachomatis detection by real-time PCR was performed. The infertility causes were obtained from their medical records. The prevalence of infection was 8.68%. The percentage of concordance was 22.4% (13 couples). A presence of tubal occlusion was only associated with infected-discordant women [RR = 3.46, 95% CI (1.54-7.74), p < .003]. Seminal values were not associated with discordant men. The concordant couples showed association with the infection and tubal occlusion [RR = 3.19, 95% CI (1.09-9.34), p < .05], and oligozoospermia [RR = 12.17, 95% CI (4.29-34.54), p < .001], hypospermia [RR = 14.13, 95% CI (4.78-41.84), p < .001]. An alteration in semen quality was shown particularly in men whose sexual partners show a tubal pathology. This could occur due to a C. trachomatis infection in the testis, which underlines the need to carry out effective and efficient strategies to identify and treat all sexual partners exposed to C. trachomatis.

Characterization of the Horizontal and Vertical Sexual Transmission of Chlamydia Genital Infections in a New Mouse Model

Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen worldwide, and there is a need to control this epidemic. So far there is no established animal model in which both the horizontal and the vertical transmission of Chlamydia can be studied. To implement a horizontal sexual transmission model, male mice were inoculated in the meatus urethra with Chlamydia muridarum and they were caged with naive female mice. Urine and vaginal swab specimens were collected for culture. To study vertical transmission, newborns were euthanized and specimens were cultured. As controls, females were mated with sham-infected male mice. All C. muridarum-inoculated male mice had positive urine cultures. As determined by serology, all females caged with C. muridarum-inoculated males became infected, and 93% of them had positive vaginal swab specimen cultures. More females mated with C. muridarum-infected male mice (35%) than females mated with sham-infected male mice (0%) were infertile (P < 0.05). Also, C. muridarum-infected females delivered significantly fewer pups (3.8 ± 3.2/mouse) than control females (6.3 ± 1.6/mouse) (P < 0.05). Of the newborn mice, 32% were C. muridarum positive either in the lungs or in the intestines. Female mice housed with sham-infected males had no positive vaginal swab specimen cultures or C. muridarum-positive pups. This new mouse model of horizontal and vertical sexual transmission of Chlamydia closely parallels C. trachomatis sexual transmission in humans and may be a good model system to better understand the pathogenesis of these infections.

Simultaneous profiling of sexually transmitted bacterial pathogens, microbiome, and concordant host response in cervical samples using whole transcriptome sequencing analysis

Pelvic inflammatory disease (PID) is a female upper genital tract inflammatory disorder that arises after sexually transmitted bacterial infections (STI). Factors modulating risk for reproductive sequelae include co-infection, microbiota, host genetics and physiology. In a pilot study of cervical samples obtained from women at high risk for STIs, we examined the potential for unbiased characterization of host, pathogen and microbiome interactions using whole transcriptome sequencing analysis of ribosomal RNA-depleted total RNAs (Total RNA-Seq). Only samples from women with STI infection contained pathogen-specific sequences (3 to 38% transcriptome coverage). Simultaneously, we identified and quantified their active microbial communities. After integration with host-derived reads from the same data, we detected clustering of host transcriptional profiles that reflected microbiome differences and STI infection. Together, our study suggests that total RNA profiling will advance understanding of the interplay of pathogen, host and microbiota during natural infection and may reveal novel, outcome-relevant biomarkers.

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.

Chlamydia Infection Between Men and Women: A Cross-Sectional Study of Heterosexual Partnerships

Background

Studies of sexual partnerships can further our understanding of the sexual transmission of chlamydia, which is important for informing public health interventions and clinical management. The aim of this study was to ascertain among heterosexual dyads the proportion concordantly infected with chlamydia and factors associated with infection between partners.

Methods

This study was conducted at the Melbourne Sexual Health Centre between January 2006 and March 2015. Heterosexual partners attending the clinic on the same day were identified prospectively. Dyads where 1 or both individuals were diagnosed with chlamydia by a test performed on the day of joint attendance or within the prior 30 days were included. Testing was by strand displacement assay. Men and women with genital symptoms underwent clinical examination.

Results

Of 233 females with chlamydia, 76% (n = 178) of their male partners tested positive. Of the chlamydia-positive females with cervicitis, 91% of males were chlamydia positive. Male infection was less likely if their partner had taken azithromycin or doxycycline within 30 days (7% vs 25%; P = .039). Of 235 males with chlamydia, 77% (n = 178) of their female partners tested positive. No associations were found between male symptoms, signs, or recent antibiotic use and a positive chlamydia result in female partners. Sixty-one percent of the dyads were concordantly infected with chlamydia.

Conclusions

These results underscore the high likelihood of heterosexual partners of men and women with chlamydia being infected and the importance that partners are tested and managed appropriately for chlamydia.

Concordance of chlamydia infections of the rectum and urethra in same-sex male partnerships: a cross-sectional analysis

Background

Our study aimed to describe the concordance of chlamydia infections of the rectum and urethra in men who have sex with men (MSM) and their male partners.

Methods

This was a cross-sectional study of chlamydia in MSM and their male sexual partners both attending Melbourne Sexual Health Centre (MSHC), Australia, between February 2011 and March 2015. We excluded partnerships where testing for chlamydia at both the rectum and urethra were not undertaken.

Results

Our study included 473 partnerships (946 men). 30 men had urethral chlamydia, of whom 14 (47%, 95% CI 28 to 66) had a partner with rectal chlamydia. 46 men had rectal chlamydia, of whom 14 (30%, 95% CI 18 to 46) had a partner with urethral chlamydia. The proportion of men with rectal chlamydia when their partner had urethral chlamydia was significantly higher than the proportion of men with urethral chlamydia when their partner had rectal chlamydia (McNemar’s p = 0.02).

Conclusions

This is the first study of chlamydia concordance in male sexual partnerships and suggests that transmission of chlamydia between the urethra and rectum may be less efficient than has been reported for transmission between the urethra and cervix in heterosexual couples. It also suggests that transmission from the urethra to the rectum may be more efficient than in the opposite direction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2141-7) contains supplementary material, which is available to authorized users.