Roles of bovine Waddlia chondrophila and Chlamydia trachomatis in human preterm birth

Relationship between Vaginal Bacterial Infections and Pregnancy Outcomes: A Systematic Review and Meta-Analysis

Background

Bacterial infections are among the most serious infections worldwide. They can cause miscarriage, premature birth, stillbirth, and ectopic pregnancy in pregnant women. The aim of this study was to investigate the relationship between bacterial infections and pregnancy outcomes through a systematic review and meta-analysis.

Materials and Methods

PubMed, Scopus, Web of Science, and Embase databases were searched from January 2000 to December 2018 using appropriate keywords to identify related articles. The final related studies were selected and evaluated using the Newcastle-Ottawa Scale (NOS).

Results

Results of this meta-analysis based on combining case-control studies showed that the presence of bacterial infections could lead increase in the odds of all pregnancy outcomes like premature infant birth (odd ratio [OR]: 1.50; 95% Confidence Interval [CI], 1.39-1.61), preterm delivery (OR: 1.54; 95% CI, 1.39-1.70), abortion (OR: 1.16; 95% CI, 1.04-1.29), stillbirth (OR, 1.29; 95% CI, 1.12-1.49), and ectopic pregnancy (OR: 1.12; 95% CI, 1.05--1.19). The results showed that the Risk Ratio (RR) of preterm delivery in pregnant women with vaginal infections was 1.57 (95% CI, 1.46-1.67), whereas the RR of abortion was 2.02 (95% CI, 1.72-2.38).

Conclusions

Based on the results of this meta-analysis, the presence of bacterial infections in pregnant women can lead increase in the risk of pregnancy outcomes especially, preterm delivery, abortion, stillbirth, and ectopic pregnancy. Therefore, it is necessary for obstetricians and gynecologists to pay attention to the diagnosis of these infections in women before pregnancy and during pregnancy in order to prevent the consequences of these infections.

The role of chlamydiales in adverse pregnancy outcome: a community-based nested case-control study

OBJECTIVES

Over the last decades, the Chlamydiales order has expanded and a new group of Chlamydia-related bacteria has emerged, covering species like Waddlia (W.) chondrophila associated with bovine abortion. However, it is unknown whether they compromise human reproduction like Chlamydia (C.) trachomatis. We therefore aimed to investigate the association between vaginal colonisation of selected species of the Chlamydiales order with spontaneous abortion, preterm birth, and, animal exposure.

METHODS

Pregnant women were enrolled at the nuchal translucency scan or when admitted for suspected miscarriage at Aarhus University Hospital, Denmark. Cases were defined as spontaneous abortion <22 weeks and preterm birth <37 weeks. Controls were defined as term birth ≥37 weeks. Vaginal samples from 1203 women were assessed using C.trachomatis, W.chondrophila and pan-Chlamydiales specific real-time PCRs targeting the 16S rRNA gene.

RESULTS

A total of 1120 women of primarily Caucasian ancestry were enrolled, including 193 spontaneous abortions, 88 preterm births, and 839 term births. After sequencing for verification, the prevalence of Chlamydiales was 3/193 (1.6%, 95%CI 0.5-4.8) in women experiencing spontaneous abortion, 2/88 (2.3%, 95%CI 0.6-8.9) in women with preterm birth, and 20/839 (2.4%, 95%CI 1.6-3.7) in women giving birth at term. Thus, Chlamydiales infection was neither significantly associated with spontaneous abortion (OR 0.68, 95%CI 0.15-2.01) nor preterm birth (OR 1.02, 95%CI 0.15-3.60) compared to women giving birth at term. Amplicons from the pan-Chlamydiales assay revealed close sequence homology and were primarily identified as uncultured Chlamydiales bacteria.

CONCLUSIONS

Among Danish pregnant women, the prevalence of Chlamydiales was low and not associated with adverse pregnancy outcomes.

Dynamics of the Gut Bacteriome During a Laboratory Adaptation Process of the Mediterranean Fruit Fly, Ceratitis capitata

Laboratory adaptation process used in sterile insect technique (SIT) programs can exert a significant impact on the insect-gut microbiome relationship, which may negatively impact the quality and performance of the fly. In the present study, changes in the gut microbiota that occur through laboratory adaptation of two Ceratitis capitata populations were investigated: Vienna 8 genetic sexing strain (GSS), a long-established control line, and a wild population recently introduced to laboratory conditions. The bacterial profiles were studied for both strains using amplicon sequencing of the 16S rRNA V3-V4 hypervariable region in larvae and in the gastrointestinal tract of teneral (1 day) and adults (5 and 15 days) reared under laboratory conditions for 14 generations (F0-F13). Findings demonstrated the development of distinct bacterial communities across the generations with differences in the bacterial composition, suggesting a strong impact of laboratory adaptation on the fly bacteriome. Moreover, different bacterial profiles were observed between wild and Vienna 8 FD-GSS displaying different patterns between the developmental stages. Proteobacteria, mainly members of the Enterobacteriaceae family, represented the major component of the bacterial community followed by Firmicutes (mainly in Vienna 8 FD-GSS adults) and Chlamydiae. The distribution of these communities is dynamic across the generations and seems to be strain- and age-specific. In the Vienna 8 FD-GSS population, Providencia exhibited high relative abundance in the first three generations and decreased significantly later, while Klebsiella was relatively stable. In the wild population, Klebsiella was dominant across most of the generations, indicating that the wild population was more resistant to artificial rearing conditions compared with the Vienna 8 FD-GSS colony. Analysis of the core bacteriome revealed the presence of nine shared taxa between most of the examined medfly samples including Klebsiella, Providencia, Pantoea, and Pseudomonas. In addition, the operational taxonomic unit co-occurrence and mutual exclusion networks of the wild population indicated that most of the interactions were classified as co-presence, while in the Vienna 8 FD-GSS population, the number of mutual exclusions and co-presence interactions was equally distributed. Obtained results provided a thorough study of the dynamics of gut-associated bacteria during the laboratory adaptation of different Ceratitis capitata populations, serving as guidance for the design of colonization protocols, improving the effectiveness of artificial rearing and the SIT application.

Evaluation of a Multiplex Real-Time PCR Assay for Detecting Chlamydia trachomatis in Vaginal Samples

Chlamydia trachomatis is an important cause of sexually transmitted infections (STI) in Western countries. It is often asymptomatic, and thus, left untreated, and can have severe negative consequences, such as tubal infertility or adverse pregnancy outcomes. Other sexually transmitted microorganisms, such as Neisseria gonorrhoeae and Trichomonas vaginalis, as well as normal residents of the vaginal flora, such as genital mycoplasmas, also negatively impact human sexual and reproductive health. We evaluated the reliability of the Seegene Allplex STI Essential Assay for C. trachomatis detection using the real-time qPCR routinely used in our diagnostic laboratories as the gold standard. The Seegene assay displayed a sensitivity of 97.8% and a specificity of 98.9%. As this assay can also detect six other urogenital pathogens, we applied it to 404 samples from women who attended Lausanne University Maternity Hospital and obtained the following prevalence rates: 2.5% for C. trachomatis, 3.5% for Mycoplasma hominis, 6.3% for Ureaplasma urealyticum, and 27.7% for Ureaplasma parvum. Two samples were positive for Trichomonas vaginalis, and one sample was positive for Mycoplasma genitalium. Bacterial vaginosis was present in 4.5% of the cases and was strongly associated with M. hominis. Finally, we confirmed the association between C. trachomatis infection and pre-term birth (p = 0.03) but could not detect any association of this condition with other urogenital pathogens (Mycoplasma/Ureaplasma). In conclusion, given its high sensitivity and specificity for C. trachomatis DNA detection as well as its multiplex format, which simultaneously provides results for six other urogenital pathogens, the Seegene Allplex™ STI Essential Assay represents an appealing diagnostic tool in modern microbiology laboratories.

Genital Chlamydia Trachomatis Infection: Prevalence, Risk Factors and Adverse Pregnancy and Birth Outcomes in Children and Women in sub-Saharan Africa

Genital Chlamydia trachomatis (CT) has adverse health outcomes for women and children. In pregnant women, the infection causes adverse obstetric outcomes including pelvic inflammation, ectopic pregnancy, and miscarriage. In children, it causes adverse birth outcomes such as skin rash, lesions, limb abnormalities, conjunctivitis, neurological damage, and even death. This article discusses genital CT prevalence, risk factors, and adverse pregnancy and birth outcomes among women and children in sub-Saharan Africa as well as challenges associated with the mitigation of the disease. A comprehensive search of databases including PubMed, ResearchGate, and Google Scholar was conducted using keywords such as genital chlamydia trachomatis, adverse pregnancy outcomes, adverse birth outcomes, and sub-Saharan African. We found that genital CT prevalence rates in some sub-Saharan Africa countries were higher than others and that risk factors such as the lack of condom use, having multiple sexual partners, and low educational levels contribute to the transmission of the infection. We also found that negative cultural practices, illiteracy among women, and the lack of access to screening services during pregnancy are some of the challenges associated with CT mitigation in sub-Saharan Africa. To reduce genital CT transmission in sub-Saharan Africa, efforts must be made by country governments to eliminate negative cultural practices, promote female literacy, and provide access to screening services for pregnant women.

Screening of Chlamydia trachomatis and Waddlia chondrophila Antibodies in Women with Tubal Factor Infertility

Waddlia chondrophila is an emerging intracellular pathogen belonging to the order of Chlamydiales, and was previously associated with adverse pregnancy outcomes, as well as tubal factor infertility (TFI). In this study, we investigate the link between both W. chondrophila and Chlamydia trachomatis IgG seropositivity and TFI. Antibodies against both bacteria were measured in 890 serum samples of women visiting a fertility clinic. After a hysterosalpingography and/or laparoscopy, they were classified as either TFI-negative (TFI−) or TFI-positive (TFI+). The total seroprevalence was 13.4% for C. trachomatis and 38.8% for W. chondrophila. C. trachomatis antibodies were present significantly more often in the TFI+ group than in the TFI− group, while for W. chondrophila no difference could be observed. In conclusion, our study confirms the association between C. trachomatis seropositivity and TFI, but no association was found between W. chondrophila seropositivity and TFI. The high percentage of W. chondrophila seropositivity in all women attending a fertility clinic does, however, demonstrate the need for further research on this Chlamydia-like bacterium and its possible role in infertility.

Detection of urinary Chlamydia trachomatis, Mycoplasma genitalium and human papilloma virus in the first trimester of pregnancy by PCR method

BACKGROUND

Miscarriage and preterm delivery are the most important challenges of pregnancy. Different bacterial and viral infection may cause miscarriage and preterm delivery. Among bacterial factors, Mycoplasma genitalium and Chlamydia trachomatis have the most important role and human papilloma virus (HPV) is the leading viral factor in this regard.

METHODS

First void urine samples were collected from 119 pregnant women who visited health centers for routine first-trimester screening (12-14 weeks gestation). About 10 ml of the sample was centrifuged at 3000×g for 20 min and 1-2 ml of the sediment was transferred to sterile microfuges and stored at - 20 °C until analysis. DNA extraction was conducted using A101211 kits imported by Pars Tous Biotechnology Company. The following commercial kits, imported by Pars Tous Biotechnology, were used for PCR.

RESULTS

There is no significant association between urinary isolation of C. trachomatis and miscarriage (P = 0.93) and there is no significant association between urinary isolation of M. genitalium and miscarriage (P = 0.80). Regarding HPV, since all urine samples were PCR-negative, comparison was not possible. C. trachomatis was isolated from the urine samples of 6.72% of the pregnant women who underwent first-trimester screening in health centers using PCR. Previous studies reported a mean chlamydia isolation rate of 3% from urine specimens collected from pregnant women in general. T test showed no significant difference between the two groups (P = 0.10). Based on present study the mycoplasma isolation rate was 17.65% using PCR. Previous studies reported a mean mycoplasma isolation rate of 10% from urine specimens collected from pregnant women in general. T-test showed a significant difference between the two groups (P = 0.03).

DISCUSSION

First void urine samples in pregnant women may be an appropriate sample for detection of C. trachomatis and M. genitalium; however, it is not a good method for HPV isolation therefore vaginal or cervical discharge specimens should be used instead for detection of HPV.

Prenatal inflammation exposure-programmed cardiovascular diseases and potential prevention

In recent years, the rapid development of medical and pharmacological interventions has led to a steady decline in certain noncommunicable chronic diseases (NCDs), such as cancer. However, the overall incidence of cardiovascular diseases (CVDs) has not seemed to decline. CVDs have become even more prevalent in many countries and represent a global health threat and financial burden. An increasing number of epidemiological and experimental studies have demonstrated that maternal insults not only can result in birth defects but also can cause developmental functional defects that contribute to adult NCDs. In the current review, we provide an overview of evidence from both epidemiological investigations and experimental animal studies supporting the concept of developmental reprogramming of adult CVDs in offspring that have experienced prenatal inflammation exposure (PIE) during fetal development (PIE-programmed CVDs), a disease-causing event that has not been effectively controlled. This review describes the epidemiological observations, data from animal models, and related mechanisms for the pathogenesis of PIE-programmed CVDs. In addition, the potential therapeutic interventions of PIE-programmed CVDs are discussed. Finally, we also deliberate the need for future mechanistic studies and biomarker screenings in this important field, which creates a great opportunity to combat the global increase in CVDs by managing the adverse effects of inflammation for prepregnant and pregnant individuals who are at risk for PIE-programmed CVDs.

Chlamydia trachomatis and chlamydia-like bacteria: new enemies of human pregnancies

PURPOSE OF REVIEW

This review provides an update on the roles of Chlamydia trachomatis and the related Waddlia chondrophila and Parachlamydia acanthamoebae in miscarriage, stillbirths and preterm labour in humans. A broad audience, including microbiologist, infectiologists, obstetricians and gynaecologists, should be aware of the potential threat of these Chlamydiales for human reproduction.

RECENT FINDINGS

Despite increasing laboratory techniques and possibilities to perform diagnostic tests, the cause of miscarriage is only identified in 50% of the cases. Intracellular bacteria, such as C. trachomatis and Chlamydia-related bacteria, are difficult to detect in routine clinical samples and could represent possible agents of miscarriages. C. trachomatis is considered the world largest sexual transmitted bacterial agent and is associated with adverse pregnancy outcome in human. In the last decade Chlamydia-like organisms, such as W. chondrophila and P. acanthamoebae, have also been associated with adverse pregnancy outcomes in human and/or animals.

SUMMARY

We review here the current evidences for a pathogenic role in humans, the diagnostic approaches and possible treatment options of C. trachomatis, W. chondrophila and P. acanthamoebae.

Insight in the biology of Chlamydia-related bacteria

The Chlamydiales order is composed of obligate intracellular bacteria and includes the Chlamydiaceae family and several family-level lineages called Chlamydia-related bacteria. In this review we will highlight the conserved and distinct biological features between these two groups. We will show how a better characterization of Chlamydia-related bacteria may increase our understanding on the Chlamydiales order evolution, and may help identifying new therapeutic targets to treat chlamydial infections.

Chlamydia related bacteria (Chlamydiales) in early pregnancy: community-based cohort study

Objectives

Serological case–control studies suggest that certain chlamydia-related bacteria (Chlamydiales) which cause cows to abort may do the same in humans. Chlamydiales include Waddlia chondrophila, Chlamydia abortus and Chlamydia trachomatis. Data on prevalence of Chlamydiales in pregnancy are sparse. Using stored urine samples from a carefully characterised cohort of 847 newly pregnant women recruited from 37 general practices in London, UK, we aimed to investigate the prevalence and types of Chlamydiales infections. We also explored possible associations with miscarriage or spontaneous preterm birth.

Methods

Samples were tested using W. chondrophila and pan-Chlamydiales specific real-time PCRs targeting the 16S rRNA gene. Samples positive on either PCR were subjected to DNA sequencing and C. trachomatis PCR.

Results

The overall prevalence of Chlamydiales was 4.3% (36/847, 95% CI 3.0% to 5.8%). The prevalence of W. chondrophila was 0.6% (n = 5), C. trachomatis 1.7% (n = 14), and other Chlamydiales species 2.0% (n = 17). Infection with C. trachomatis was more common in women aged <25, of black ethnicity or with bacterial vaginosis, but this did not apply to W. chondrophila or other Chlamydiales.

Follow up was 99.9% at 16 weeks gestation and 90% at term. No infection was significantly associated with miscarriage at ≤12 weeks (prevalence 10%, 81/827) or preterm birth <37 weeks (prevalence 4%, 23/628). Of 25 samples sequenced, seven (28%) were positive for Chlamydiales bacterium sequences associated with respiratory tract infections in children.

Conclusion

In the first study to use the pan-Chlamydiales assay on female urine samples, 4% of pregnant women tested positive for Chlamydiales, including species known to be pathogenic in mothers and neonates.

Emerging Role of Zika Virus in Adverse Fetal and Neonatal Outcomes

The rapid spread of the Zika virus (ZIKV) in the Americas and its potential association with thousands of suspected cases of microcephaly in Brazil and higher rates of Guillain-Barré syndrome meet the conditions for a Public Health Emergency of International Concern, as stated by the World Health Organization in February 2016. Two months later, the Centers for Disease Control and Prevention (CDC) announced that the current available evidence supports the existence of a causal relationship between prenatal Zika virus infection and microcephaly and other serious brain anomalies. Microcephaly can be caused by several factors, and its clinical course and prognosis are difficult to predict. Other pathogens with proven teratogenicity have been identified long before the current ZIKV epidemic. Despite the growing number of cases with maternal signs of infection and/or presence of ZIKV in tissues of affected newborns or fetuses, it is currently difficult to assess the magnitude of increase of microcephaly prevalence in Brazil, as well as the role of other factors in the development of congenital neurological conditions. Meanwhile, health agencies and medical organizations have issued cautious guidelines advising health care practitioners and expectant couples traveling to, returning from, or living in affected areas. Analogous to dengue virus (DENV) epidemics, ZIKV has the potential to become endemic in all countries infested by Aedes mosquitoes, while new mutations could impact viral replication in humans, leading to increased virulence and consequently heightened chances of viral transmission to additional naive mosquito vectors. Studies are urgently needed to answer the questions surrounding ZIKV and its role in congenital neurological conditions.

Association of Chlamydia trachomatis with infertility and clinical manifestations: a systematic review and meta-analysis of case-control studies

Background Chlamydia trachomatis is one of the sexually transmitted pathogens causing reproductive health-threatening diseases worldwide. However, its role in infertility, particularly in asymptomatic individuals, is not yet definitely determined. Methods For the study, electronic databases were searched using the following keywords; 'Chlamydia trachomatis', 'prevalence', 'frequency', 'fertile', 'infertile', 'case', 'control', 'symptomatic' and 'asymptomatic'. Finally, after some exclusions, 34 studies (19 fertile-infertile and 15 symptomatic-asymptomatic) from different countries were included in the study and meta-analysis was performed on the data collected. Results Odds ratios (ORs) for urogenital C. trachomatis prevalence in males in the fertile-infertile group, for infertile and fertile individuals, ranged from 1.3-3.7 and in females from 1.04-4.8, and the overall OR for both genders was 2.2 (95% CI). In the symptomatic-asymptomatic group, the overall OR in males and females was 4.9 (95% CI = 1.1-21.7) and 3.3 (95% CI = 1.7-6.3), respectively. In all of the analyses, there were high levels of heterogeneity (I(2) >50%, p-value <0.05) and, except for the females in the symptomatic-asymptomatic group, neither Egger's tests nor Begg's tests were statistically significant for publication bias. Conclusions C. trachomatis can impact on the potential for fertility and cause clinical manifestations and complications in both males and females. Thus, national programmes for adequate diagnosis, screening and treatment of infected individuals, particularly asymptomatic ones, seem to be necessary.

Chlamydia trachomatis Infection in Pregnancy: The Global Challenge of Preventing Adverse Pregnancy and Infant Outcomes in Sub-Saharan Africa and Asia

Screening and treatment of sexually transmitted infections (STIs) in pregnancy represents an overlooked opportunity to improve the health outcomes of women and infants worldwide. Although Chlamydia trachomatis is the most common treatable bacterial STI, few countries have routine pregnancy screening and treatment programs. We reviewed the current literature surrounding Chlamydia trachomatis in pregnancy, particularly focusing on countries in sub-Saharan Africa and Asia. We discuss possible chlamydial adverse pregnancy and infant health outcomes (miscarriage, stillbirth, ectopic pregnancy, preterm birth, neonatal conjunctivitis, neonatal pneumonia, and other potential effects including HIV perinatal transmission) and review studies of chlamydial screening and treatment in pregnancy, while simultaneously highlighting research from resource-limited countries in sub-Saharan Africa and Asia.

Chlamydial polymorphic membrane proteins: regulation, function and potential vaccine candidates

Pmps (Polymorphic Membrane Proteins) are a group of membrane bound surface exposed chlamydial proteins that have been characterized as autotransporter adhesins and are important in the initial phase of chlamydial infection. These proteins all contain conserved GGA (I, L, V) and FxxN tetrapeptide motifs in the N-terminal portion of each protein. All chlamydial species express Pmps. Even in the chlamydia-related bacteria Waddlia chondrophila, a Pmp-like adhesin has been identified, demonstrating the importance of Pmps in Chlamydiales biology. Chlamydial species vary in the number of pmp genes and their differentially regulated expression during the infectious cycle or in response to stress. Studies have also demonstrated that Pmps are able to induce innate immune functional responses in infected cells, including production of IL-8, IL-6 and MCP-1, by activating the transcription factor NF-κB. Human serum studies have indicated that although anti-Pmp specific antibodies are produced in response to a chlamydial infection, the response is variable depending on the Pmp protein. In C. trachomatis, PmpB, PmpC, PmpD and PmpI were the proteins eliciting the strongest immune response among adolescents with and without pelvic inflammatory disease (PID). In contrast, PmpA and PmpE elicited the weakest antibody response. Interestingly, there seems to be a gender bias for Pmp recognition with a stronger anti-Pmp reactivity in male patients. Furthermore, anti-PmpA antibodies might contribute to adverse pregnancy outcomes, at least among women with PID. In vitro studies indicated that dendritic cells infected with C. muridarum were able to present PmpG and PmpF on their MHC class II receptors and T cells were able to recognize the MHC class-II bound peptides. In addition, vaccination with PmpEFGH and Major Outer Membrane Protein (MOMP) significantly protected mice against a genital tract C. muridarum infection, suggesting that Pmps may be an important component of a multi-subunit chlamydial vaccine. Thus, Pmps might be important not only for the pathogenesis of chlamydial infection, but also as potential candidate vaccine proteins.

Waddlia: An emerging pathogen and a model organism to study the biology of chlamydiae

Waddlia chondrophila is an emerging pathogen associated with abortion in cattle. In humans, a growing body of evidence supports its pathogenic role in miscarriage and in respiratory tract infection. The human pathogenicity of W. chondrophila is further supported by the presence of several virulence factors including a catalase, a functional T3SS and several adhesins. Despite this medical importance, no commercial tests are available and diagnostic of this strict intracellular bacterium mainly relies on serology, PCR and immunohistochemistry. So far, the epidemiology of W. chondrophila remains largely unexplored and zoonotic, waterborne or interhuman transmission has been considered. Apart from its pathogenic role, chlamydiologists are also interested in W. chondrophila in order to better understand biological mechanisms conserved and shared with Chlamydia spp. Indeed, W. chondrophila proved to be a useful model organism to study the pathobiology of chlamydiae thanks to its rapid replication, its large size allowing precise subcellular protein localization, as well as its growth in Dictyostelium amoebae.

Purification and proteomics of pathogen-modified vacuoles and membranes

Certain pathogenic bacteria adopt an intracellular lifestyle and proliferate in eukaryotic host cells. The intracellular niche protects the bacteria from cellular and humoral components of the mammalian immune system, and at the same time, allows the bacteria to gain access to otherwise restricted nutrient sources. Yet, intracellular protection and access to nutrients comes with a price, i.e., the bacteria need to overcome cell-autonomous defense mechanisms, such as the bactericidal endocytic pathway. While a few bacteria rupture the early phagosome and escape into the host cytoplasm, most intracellular pathogens form a distinct, degradation-resistant and replication-permissive membranous compartment. Intracellular bacteria that form unique pathogen vacuoles include Legionella, Mycobacterium, Chlamydia, Simkania, and Salmonella species. In order to understand the formation of these pathogen niches on a global scale and in a comprehensive and quantitative manner, an inventory of compartment-associated host factors is required. To this end, the intact pathogen compartments need to be isolated, purified and biochemically characterized. Here, we review recent progress on the isolation and purification of pathogen-modified vacuoles and membranes, as well as their proteomic characterization by mass spectrometry and different validation approaches. These studies provide the basis for further investigations on the specific mechanisms of pathogen-driven compartment formation.