An investigation into swab and urine samples for the detection of chlamydia trachomatis genital infections

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An online study combining the constructs from the theory of planned behaviour and protection motivation theory in predicting intention to test for chlamydia in two testing contexts

Chlamydia is a common sexually transmitted infection that has potentially serious consequences unless detected and treated early. The health service in the UK offers clinic-based testing for chlamydia but uptake is low. Identifying the predictors of testing behaviours may inform interventions to increase uptake. Self-tests for chlamydia may facilitate testing and treatment in people who avoid clinic-based testing. Self-testing and being tested by a health care professional (HCP) involve two contrasting contexts that may influence testing behaviour. However, little is known about how predictors of behaviour differ as a function of context. In this study, theoretical models of behaviour were used to assess factors that may predict intention to test in two different contexts: self-testing and being tested by a HCP. Individuals searching for or reading about chlamydia testing online were recruited using Google Adwords. Participants completed an online questionnaire that addressed previous testing behaviour and measured constructs of the Theory of Planned Behaviour and Protection Motivation Theory, which propose a total of eight possible predictors of intention. The questionnaire was completed by 310 participants. Sufficient data for multiple regression were provided by 102 and 118 respondents for self-testing and testing by a HCP respectively. Intention to self-test was predicted by vulnerability and self-efficacy, with a trend-level effect for response efficacy. Intention to be tested by a HCP was predicted by vulnerability, attitude and subjective norm. Thus, intentions to carry out two testing behaviours with very similar goals can have different predictors depending on test context. We conclude that interventions to increase self-testing should be based on evidence specifically related to test context.

Perceptions of self-testing for chlamydia:understanding and predicting self-test use

Background: Self-testing technology allows people to test themselves for chlamydia without professional support. This may result in reassurance and wider access to chlamydia testing, but anxiety could occur on receipt of positive results. This study aimed to identify factors important in understanding self-testing for chlamydia outside formal screening contexts, to explore the potential impacts of self-testing on individuals, and to identify theoretical constructs to form a Framework for future research and intervention development. Methods: Eighteen university students participated in semi-structured interviews; eleven had self-tested for chlamydia. Data were analysed thematically using a Framework approach. Results: Perceived benefits of self-testing included its being convenient, anonymous and not requiring physical examination. There was concern about test accuracy and some participants lacked confidence in using vulvo-vaginal swabs. While some participants expressed concern about the absence of professional support, all said they would seek help on receiving a positive result. Factors identified in Protection Motivation Theory and the Theory of Planned Behaviour, such as response efficacy and self-efficacy, were found to be highly salient to participants in thinking about self-testing. Conclusions: These exploratory findings suggest that self-testing independently of formal health care systems may no more negatively impact people than being tested by health care professionals. Participants’ perceptions about self-testing behaviour were consistent with psychological theories. Findings suggest that interventions which increase confidence in using self-tests and that provide reassurance of test accuracy may increase self-test intentions.

Caractérisation des infections à Chlamydia trachomatis persistantes induites par l'action des antibiotiques

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Defining the Role of Host Cell Chromatin Traps in Chlamydia trachomatis Pathogenesis

Chlamydia trachomatis (CT) is the most common bacterial agent of sexually transmitted infection and can cause damaging inflammation of the female reproductive tract. As an obligate intracellular pathogen, CT must exit exhausted host cells in a manner that favors successful dissemination. Epithelial cells infected with CT expel decondensed nuclear chromatin at the conclusion of an infectious cycle, and these ensnare CT particles. Whether these chromatin traps benefit the host or the pathogen is not obvious. The overall goal of this work is to begin discerning between these possibilities by determining how chromatin traps impact CT survival following exit and how traps contribute to CT-induced inflammatory processes.

Caractérisation des infections à Chlamydia trachomatis persistantes induites par l'action des antibiotiques

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Association of human papillomavirus and Chlamydia trachomatis with intraepithelial alterations in cervix samples

The influence of different infectious agents and their association with human papillomavirus (HPV) in cervical carcinogenesis have not been completely elucidated. This study describes the association between cytological changes in cervical epithelium and the detection of the most relevant aetiological agents of sexually transmitted diseases. Samples collected from 169 patients were evaluated by conventional cytology followed by molecular analysis to detect HPV DNA, Chlamydia trachomatis , herpes simplex virus 1 and 2, Neisseria gonorrhoeae , Mycoplasma genitalium , Trichomonas vaginalis, and Treponema pallidum , besides genotyping for most common high-risk HPV. An association between cytological lesions and different behavioural habits such as smoking and sedentariness was observed. Intraepithelial lesions were also associated with HPV and C. trachomatis detection. An association was also found between both simple and multiple genotype infection and cytological changes. The investigation of HPV and C. trachomatis proved its importance and may be considered in the future for including in screening programs, since these factors are linked to the early diagnosis of patients with precursor lesions of cervical cancer.

Identification, characterisation and expression analysis of natural killer receptor genes in chlamydia pecorum infected koalas (phascolarctos cinereus)

BACKGROUND: Koalas (Phascolarctos cinereus), an iconic Australian marsupial, are being heavily impacted by the spread of Chlamydia pecorum, an obligate intracellular bacterial pathogen. Koalas vary in their response to this pathogen, with some showing no symptoms, while others suffer severe symptoms leading to infertility, blindness or death. Little is known about the pathology of this disease and the immune response against it in this host. Studies have demonstrated that natural killer (NK) cells, key components of the innate immune system, are involved in the immune response to chlamydial infections in humans. These cells can directly lyse cells infected by intracellular pathogens and their ability to recognise these infected cells is mediated through NK receptors on their surface. These are encoded in two regions of the genome, the leukocyte receptor complex (LRC) and the natural killer complex (NKC). These two families evolve rapidly and different repertoires of genes, which have evolved by gene duplication, are seen in different species. METHODS: In this study we aimed to characterise genes belonging to the NK receptor clusters in the koala by searching available koala transcriptomes using a combination of search methods. We developed a qPCR assay to quantify relative expression of four genes, two encoded within the NK receptor cluster (CLEC1B, CLEC4E) and two known to play a role in NK response to Chalmydia in humans (NCR3, PRF1). RESULTS: We found that the NK receptor repertoire of the koala closely resembles that of the Tasmanian devil, with minimal genes in the NKC, but with lineage specific expansions in the LRC. Additional genes important for NK cell activity, NCR3 and PRF1, were also identified and characterised. In a preliminary study to investigate whether these genes are involved in the koala immune response to infection by its chlamydial pathogen, C. pecorum, we investigated the expression of four genes in koalas with active chlamydia infection, those with past infection and those without infection using qPCR. This analysis revealed that one of these four, CLEC4E, may be upregulated in response to chlamydia infection. CONCLUSION: We have characterised genes of the NKC and LRC in koalas and have discovered evidence that one of these genes may be upregulated in koalas with chlamydia, suggesting that these receptors may play a role in the immune response of koalas to chlamydia infection.

Effect of Preventive Chlamydia abortus Vaccination in Offspring Development in Sheep Challenged Experimentally

Ovine enzootic abortion, caused by Chlamydia abortus, leads to important economic losses worldwide. In addition to reproductive failures, infection may impact lamb growth during the first weeks after birth, yet this effect has not been well characterized. Vaccination can help to control the disease but variable efficacy values have been described, possibly related with factors associated with the host, the vaccine, the parameter used for efficacy determination and the challenge conditions. In this context, we evaluated the efficacy of an inactivated standard commercial vaccine and a 1/2 diluted dose in pregnant sheep challenged with C. abortus by examining multiple indicators ofvaccine effect (including incidence of reproductive failures, bacterial excretion, and evolution of weight gain of viable lambs during the first month of life). Three groups of ewes [control non-vaccinated, C (n = 18); vaccinated with standard dose, SV (n = 16) and vaccinated with 1/2 dose, DV (n = 17)], were challenged approximately 90 days post-mating and tested using direct PCR (tissue samples and vaginal swabs) and ELISA (serum) until 31 days post-reproductive outcome. There were not significant differences in the proportions of reproductive failures or bacterial shedding after birth/abortion regardless the vaccination protocol. However, a beneficial effect of vaccination on offspring growth was detected in both vaccinated groups compared with the controls, with a mean increase in weight measured at 30 days of life of 1.5 and 2.5 Kg (p = 0.056) and an increase in the geometric mean of the daily gain of 8.4 and 9.7% in lambs born from DV and SV ewes compared to controls, respectively. Our results demonstrate the effect of an inactivated vaccine in the development of the offspring of C. abortus-infected ewes at a standard and a diluted dose, an interesting finding given the difficulty in achieving sufficient antigen concentration in the production of EAE-commercial vaccines.

Persistent chlamydial infections : role in inflammation and challenges for vaccine development.

The development of chlamydial vaccines continues to be a major challenge for researchers. While acute infections are the main target of vaccine development groups, Chlamydia is well known for its ability to establish chronic or persistent infections in its host. To date, little effort has focussed specifically on the challenges of vaccines to successfully combat the chronic or persistent phase of the disease and yet this will be a necessary aspect of any fully successful chlamydial vaccine. This short review specifically examines the phenomenon of chlamydial persistence and the unique challenges that this brings to vaccine development.

CTA1-DD is an effective adjuvant for targeting anti-chlamydial immunity to the murine genital mucosa

Chlamydia trachomatis is a significant human pathogen with potentially severe disease sequelae in the genital tract, including infertility. A successful vaccine will need to effectively target immunity to the genital mucosa. Intranasal immunisation with cholera toxin (CT) can target immunity to the genital tract, but has the potential to cause neurological side effects. CTA1-DD is a non-toxic potent mucosal adjuvant which combines the enzymatic properties of CT, with a B cell targeting moiety. Here, we demonstrate that intranasal immunisation with CTA1-DD and chlamydial Major Outer Membrane Protein (MOMP) results in the induction of neutralising systemic and mucosal antibodies, and reduces the level of chlamydial shedding following intravaginal challenge with Chlamydia muridarum. Thus, CTA1-DD is an effective adjuvant for vaccine development against Chlamydia trachomatis, and possibly also a range of other genital pathogens.

Kinematics of intracellular chlamydiae provide evidence for contact-dependent development

A crucial process of chlamydial development involves differentiation of the replicative reticulate body (RB) into the infectious elementary body (EB). We present experimental evidence to provide support for a contact-dependent hypothesis for explaining the trigger involved in differentiation. We recorded live-imaging of Chlamydia trachomatis-infected McCoy cells at key times during development and tracked the temporospatial trajectories of individual chlamydial particles. We found that movement of the particles is related to development. Early to mid-developmental stages involved slight wobbling of RBs. The average speed of particles increased sharply at 24 h postinfection (after the estimated onset of RB to EB differentiation). We also investigated a penicillin-supplemented culture containing EBs, RBs, and aberrantly enlarged, stressed chlamydiae. Near-immobile enlarged particles are consistent with their continued tethering to the chlamydial inclusion membrane (CIM). We found a significantly negative, nonlinear association between speed and size/type of particles, providing further support for the hypothesis that particles become untethered near the onset of RB to EB differentiation. This study establishes the relationship between the motion properties of the chlamydiae and developmental stages, whereby wobbling RBs gradually lose contact with the CIM, and RB detachment from the CIM is coincidental with the onset of late differentiation.

Bacterial proteases from the intracellular vacuole niche ; protease conservation and adaptation for pathogenic advantage

Proteases with important roles for bacterial pathogens which specifically reside within intracellular vacuoles are frequently homologous to those which have important virulence functions for other bacteria. Research has identified that some of these conserved proteases have evolved specialised functions for intracellular vacuole residing bacteria. Unique proteases with pathogenic functions have also been described from Chlamydia, Mycobacteria, and Legionella. These findings suggest that there are further novel functions for proteases from these bacteria which remain to be described. This review summarises recent findings of novel protease functions from the intracellular human pathogenic bacteria which reside exclusively in vacuoles.