Chlamydial eye infections: Current perspectives

Addressing Challenges in Chlamydia trachomatis Detection: A Comparative Review of Diagnostic Methods

Chlamydial infections are one of the most common sexually transmitted bacterial infections worldwide, which is related to serious consequences for the mental, sexual, and reproductive health of women and men. The infection is commonly asymptomatic; consequently, screening programs for infection control have been introduced in some countries. The detection methods of Chlamydia trachomatis infections have evolved since the establishment of the first gold-standard detection method in the 1970s, the culture assay. Over the decades, many efforts were made to find methods with a higher sensitivity, until the 1990s, when, as a result of advances in molecular biology, nucleic acid amplification tests came into use with more sensitivity, and, currently, there are several available with which to detect infection. Therefore, herein, we will review the main methods used for CT detection and the differences between them, in terms of targets, infections that can be detected, sensitivity, and specificity. We will focus on some of the FDA-approved CT detection tests and highlight the major advantages and superiority of using molecular biology techniques. In addition, we will examine the larger challenges and limitations of the methods currently in use and discuss how they might be surpassed. Moreover, in this review, we will describe the next step to carry out after testing positive for CT infection.

Epidemiology of Keratoconjunctivitis Across India from 2017 to 2019: A Multicentric Hospital-Based Study

PURPOSE

Conjunctivitis is one of the most common ocular conditions in clinical practice. Human adenoviruses have been the common causative agents known to cause epidemic kerato-conjunctivitis (EKC) in India from 1996 to 2019 with a positivity range of 13.8%-65.2%. The current study was initiated to throw light on the distribution of keratoconjunctivitis causing agents across India covering a span of 3 years.

METHODS

A total of 709 swabs were collected from patients in viral transport medium (VTM), and real-time PCR was done to identify agents including Adenovirus (HAdV), Enterovirus, HSV, and Chlamydia.

RESULTS

47.8% of the samples were positive for HAdV followed by HSV (3.4%), Enterovirus (2.7%), and Chlamydia (0.6%). Overall, 386 people (54.4%) tested positive for one of these infections, with Chandigarh (88.4%) and Port Blair (71.7%) showing higher positivity rate. Pre-auricular lymphadenopathy and follicles were significantly associated with increased risk of conjunctivitis.

CONCLUSION

Epidemiology of keratoconjunctivitis in the current study revealed HAdV to be predominant causative agent. Knowledge gained in such epidemiological studies guide us in outbreak expectations, limit antibiotic over-prescription, and enhance disease prevention.

Teleost Eye Is the Portal of IHNV Entry and Contributes to a Robust Mucosal Immune Response

The ocular mucosa (OM) is an important and unique part of the vertebrate mucosal immune system. The OM plays an important role in maintaining visual function and defending against foreign antigens or microorganisms, while maintaining a balance between the two through complex regulatory mechanisms. However, the function of ocular mucosal defense against foreign pathogens and mucosal immune response in bony fish are still less studied. To acquire deeper understanding into the mucosal immunity of the OM in teleost fish, we established a study of the immune response of rainbow trout (Oncorhynchus mykiss) infected with the infectious hematopoietic necrosis virus (IHNV). Our findings revealed that IHNV could successfully infiltrate the trout's OM, indicating that the OM could be an important portal for the IHNV. Furthermore, qPCR and RNA-Seq analysis results showed that a large number of immune-related genes were significantly upregulated in the OM of trout with IHNV infection. Critically, the results of our RNA-Seq analysis demonstrated that viral infection triggered a robust immune response, as evidenced by the substantial induction of antiviral, innate, and adaptive immune-related genes in the OM of infected fish, which underscored the essential role of the OM in viral infection. Overall, our findings revealed a previously unknown function of teleost OM in antiviral defense, and provided a theoretical basis for the study of the mucosal immunity of fish.

Chlamydia trachomatis Serovar Distribution in Patients with Follicular Conjunctivitis in Iran

Objectives

Chlamydia trachomatis infects the urogenital tract and eyes. Anatomical tropism is correlated with serovars which are characterized according to the variation in the major outer membrane proteins encoded by the ompA gene. The aim of the present study was to determine the distribution of C. trachomatis serovars among patients with follicular conjunctivitis in Iran.

Materials and Methods

A total of 68 conjunctival specimens from symptomatic adults were studied for the presence of C. trachomatis using polymerase chain reaction (PCR) analysis. Serovars were determined by Omp1 PCR-RFLP analysis.

Results

C. trachomatis was detected in 38 (55.9%) of patients with follicular conjunctivitis, with higher C. trachomatis prevalence in the younger age groups. Twenty-six (38.2%) of these patients had a history of urinary tract infection. Four distinct serovars were identified in the conjunctiva samples using molecular genotyping. The most prevalent was serovar E, followed by G, I, and F.

Conclusion

Our serovar distribution indicated that chlamydial follicular conjunctivitis usually has a genital source. Genital serovars may cause eye diseases, especially in sexually active adults. On the other hand, conjunctivitis might be the only sign of sexually transmitted infection. Therefore, genotyping C. trachomatis in ocular and genital specimens could be beneficial for acquiring more detailed epidemiological information about the etiology of the disease and monitoring treatment success.

Design, Biological Evaluation, and Computer-Aided Analysis of Dihydrothiazepines as Selective Antichlamydial Agents

Chlamydia trachomatis (CT) causes the most prevalent sexually transmitted bacterial disease in the United States. The lack of drug selectivity is one of the main challenges of the current antichlamydial pharmacotherapy. The metabolic needs of CT are controlled, among others, by cylindrical proteases and their chaperones (e.g., ClpX). It has been shown that dihydrothiazepines can disrupt CT-ClpXP. Based on this precedent, we synthesized a dihydrothiazepine library and characterized its antichlamydial activity using a modified semi-high-throughput screening assay. Then, we demonstrated their ability to inhibit ClpX ATPase activity in vitro, supporting ClpX as a target. Further, our lead compound displayed a promising selectivity profile against CT, acceptable cytotoxicity, no mutagenic potential, and good in vitro stability. A two-dimensional quantitative structure-activity relationship (2D QSAR) model was generated as a support tool in the identification of more potent antichlamydial molecules. This study suggests dihydrothiazepines are a promising starting point for the development of new and selective antichlamydial drugs.

Viral Infection and Antiviral Treatments in Ocular Pathologies

Ocular viral infections are common and widespread globally. These infectious diseases are a major cause of acute red eyes and vision loss. The eye and its nearby tissues can be infected by several viral agents, causing infections with a short course and limited ocular implications or a long clinical progression and serious consequences for the function and structure of the ocular region. Several surveillance studies underline the increased emergence of drug resistance among pathogenic viral strains, limiting treatment options for these infections. Currently, in the event of resistant infections, topical or systemic corticosteroids are useful in the management of associated immune reactions in the eye, which contribute to ocular dysfunction. Many cases of viral eye infections are misdiagnosed as being of bacterial origin. In these cases, therapy begins late and is not targeted at the actual cause of the infection, often leading to severe ocular compromises, such as corneal infiltrates, conjunctival scarring, and reduced visual acuity. The present study aims at a better understanding of the viral pathogens that cause eye infections, along with the treatment options available.

Refinement of water-filtered infrared A (wIRA) irradiations of in vitro acute and persistent chlamydial infections

Water-filtered infrared A (wIRA) alone or in combination with visible light (VIS) exerts anti-chlamydial effects in vitro and in vivo in acute infection models. However, it has remained unclear whether reduced irradiation duration and irradiance would still maintain anti-chlamydial efficacy. Furthermore, efficacy of this non-chemical treatment option against persistent (chronic) chlamydial infections has not been investigated to date. To address this knowledge gap, we evaluated 1) irradiation durations of 5, 15 or 30 min in genital and ocular Chlamydia trachomatis acute infection models, 2) irradiances of 100, 150 or 200 mW/cm² in the acute genital infection model and 3) anti-chlamydial activity of wIRA and VIS against C. trachomatis serovar B and E with amoxicillin (AMX)- or interferon γ (IFN-γ)-induced persistence. Reduction of irradiation duration reduced anti-chlamydial efficacy. Irradiances of 150 to 200 mW/cm², but not 100 mW/cm², induced anti-chlamydial effects. For persistent infections, wIRA and VIS irradiation showed robust anti-chlamydial activity independent of the infection status (persistent or recovering), persistence inducer (AMX or IFN-γ) or chlamydial strain (serovar B or E). This study clarifies the requirement of 30 min irradiation duration and 150 mW/cm² irradiance to induce significant anti-chlamydial effects in vitro, supports the use of irradiation in the wIRA and VIS spectrum as a promising non-chemical treatment for chlamydial infections and provides important information for follow-up in vivo studies. Notably, wIRA and VIS exert anti-chlamydial effects on persistent chlamydiae which are known to be refractory to antibiotic treatment.

Emerging antimicrobial resistance and need for antimicrobial stewardship for ocular infections in India: A narrative review

Patients with ocular infections are at increased risk of vision impairment and may require immediate medical care to preserve their vision. Management of ocular bacterial infections has evolved in recent years and includes a pragmatic selection of broad-spectrum antibiotics based on the causative bacteria. Nevertheless, the treatment of bacterial ocular infections is increasingly becoming a challenge, as the causative bacterium acquires resistance to antibiotics through intrinsic and acquired methods. From an Indian perspective, along with the challenges of antibiotic resistance, there are other factors such as lack of knowledge on epidemiology, and lack of data on local susceptibility patterns of ocular pathogens that have significant impact on the management of ocular infections. This narrative review summarizes the available knowledge on prescribing antibiotics for five common ocular infections in India. It further highlights the significance of the understanding of antimicrobial susceptibility patterns across India as a cornerstone to promote rational use of ocular antibiotics. This review indicates that large-scale antimicrobial resistance surveillance studies can facilitate the synchronization of ophthalmic antimicrobial prescription policies with local antibiotic resistance patterns. Further, establishment of an antimicrobial stewardship program in ophthalmology can potentially increase the efficacy of diagnostic tools, and implement earlier adoption of effective antibiotics. Overall, this review provides consolidated information and key considerations for treatment decision-making of common ocular infections in India.

Ocular Surface Infection Mediated Molecular Stress Responses: A Review

Infection mediated ocular surface stress responses are activated as early defense mechanisms in response to host cell damage. Integrated stress responses initiate the host response to different types of infections and modulate the transcription of key genes and translation of proteins. The crosstalk between host and pathogen results in profound alterations in cellular and molecular homeostasis triggering specific stress responses in the infected tissues. The amplitude and variations of such responses are partly responsible for the disease severity and clinical sequelae. Understanding the etiology and pathogenesis of ocular infections is important for early diagnosis and effective treatment. This review considers the molecular status of infection mediated ocular surface stress responses which may shed light on the importance of the host stress-signaling pathways. In this review, we collated literature on the molecular studies of all ocular surface infections and summarize the results from such studies systematically. Identification of important mediators involved in the crosstalk between the stress response and activation of diverse signaling molecules in host ocular surface infection may provide novel molecular targets for maintaining the cellular homeostasis during infection. These targets can be then explored and validated for diagnostic and therapeutic purposes.

Adult inclusion conjunctivitis diagnosed by polymerase chain reaction and Giemsa stain

Adult inclusion conjunctivitis, caused by Chlamydia trachomatis, is easily underdiagnosed with nonspecific ocular manifestation. Combined scrape cytology and molecular testing may be a useful strategy for its early diagnosis. A 24-year-old healthy male complained of blurred vision, foreign body sensation, and watery discharge in his right eye for four weeks. His visual acuity was 20/20 bilaterally at his first visit. Allergic conjunctivitis was the first impression, and topical treatment with corticosteroid and anti-histamine was prescribed. However, he returned five days later without symptom improvement, and his right eye vision declined to 20/40. Subepithelial corneal infiltration of his right eye was observed. According to his personal history, his girlfriend was diagnosed with sexually transmitted chlamydial infection and genital gonorrhea. Under the suspicion of sexually transmitted adult inclusion conjunctivitis, we collected his conjunctival lavage to both real-time polymerase chain reaction, which proved chlamydial infection, and Giemsa stain, which demonstrated typical basophilic intracytoplasmic inclusions. To diagnose adult inclusion conjunctivitis, we can use real-time polymerase chain reaction or Giemsa stain to help us obtain a quick and correct diagnosis.

Bacterial eye infections associated with sexual transmission infections: A review

The objective of this work was to collect updated information on Treponema pallidum, Chlamydia trachomatis and Neisseria gonorrhoeae, causing sexually transmitted infections (STIs) and etiological agents of eye infections, to provide relevant information on this public health problem. For this, a bibliographic review was carried out using different electronic databases such as: PubMed central, google academic, Lilacs, Scopus, Science Direct and Scielo, between March 2009 and August 2019. According to the WHO, more than a million people a day contract a sexually transmitted infection. For T. pallidum, a global prevalence of 0.5% is estimated for both men and women. It is a causative agent of syphilis and ocular syphilis, which manifests as uveitis. Overall, a prevalence of 2.8% in men and 3.8% in women for C. trachomatis is estimated. It is associated with oculo-genital disease, which includes STIs, inclusion conjunctivitis in adults and neonatal ophthalmia. Among its complications is trachoma, which is the leading cause of infectious blindness worldwide. Regarding N. gonorrhoeae, it has a global selection of 0.9% and 0.7% in women and men, respectively. It manifests with gonococcal conjunctivitis and neonatal ophthalmia. We can conclude that the information that relates T. pallidum, C. trachomatis and N. gonorrhoeae with their ocular compromise problems is insufficient, and even more so if we seek to find them related to each other, which makes it difficult to access data of clinical utility for visual health.

Effects of water-filtered infrared A and visible light (wIRA/VIS) radiation on heat- and stress-responsive proteins in the retina and cornea of guinea pigs

Water-filtered infrared A and visible light (wIRA/VIS), shown to reduce chlamydial infections in vitro and in vivo, might represent an innovative therapeutic approach against trachoma, a neglected tropical disease caused by ocular infection with the bacterium C. trachomatis. In this in vivo study, we assessed the impact of wIRA radiation in combination with VIS (wavelength range 595-1400 nm, intensity 2100 W/m²) on the retina and cornea in a guinea pig animal model of inclusion conjunctivitis. We investigated the effects 19 days after wIRA/VIS irradiation by comparing a single and double wIRA/VIS treatment with a sham control. By immunolabeling and western blot analyses of critical heat- and stress-responsive proteins, we could not detect wIRA/VIS-induced changes in their expression pattern. Also, immunolabeling of specific retinal marker proteins revealed no changes in their expression pattern caused by the treatment. Our preclinical study suggests wIRA/VIS as a promising and safe therapeutic tool to treat ocular chlamydial infections.

Reducing suspicion of sexual abuse in paediatric chlamydial conjunctivitis using ompA genotyping

Chlamydia trachomatis is a Gram-negative bacterium that causes urogenital tract infections, and ocular infections including trachoma, neonatal conjunctivitis and adult chlamydial inclusion conjunctivitis. A positive C. trachomatis diagnosis in children often raises suspicions of sexual abuse. While outer membrane protein A (ompA) genotypes A-C are non-invasive and are associated with trachoma; ompA genotypes D-K are often associated with sexually transmitted urogenital infections or sexually acquired chlamydial conjunctivitis. A 10-year-old female presented with a 7-month history of unilateral conjunctivitis with itching, watering and hyperaemia. She had recently moved from an urban centre in Afghanistan to the UK. A conjunctival swab taken from the child tested positive for C. trachomatis Application of ompA genotyping to conjunctival swab chlamydial DNA demonstrated that the C. trachomatis had an ompA genotype C. Chlamydial strains with this ompA genotype cause trachoma and have never previously been associated with urogenital infection. This result supported cessation of child protection investigations.

Complement and Chlamydia psittaci: Early Complement-Dependent Events Are Important for DC Migration and Protection During Mouse Lung Infection

The zoonotic intracellular bacterium Chlamydia psittaci causes life-threatening pneumonia in humans. During mouse lung infection, complement factor C3 and the anaphylatoxin C3a augment protection against C. psittaci by a so far unknown mechanism. To clarify how complement contributes to the early, innate and the late, specific immune response and resulting protection, this study addresses the amount of C3, the timing when its presence is required as well as the anaphylatoxin receptor(s) mediating its effects and the complement-dependent migration of dendritic cells. Challenge experiments with C. psittaci on various complement KO mice were combined with transient decomplementation by pharmacological treatment, as well as the analysis of in vivo dendritic cells migration. Our findings reveal that a plasma concentration of C3 close to wildtype levels was required to achieve full protection. The diminished levels of C3 of heterozygote C3+/- mice permitted already relative effective protection and improved survival as compared to C3-/- mice, but overall recovery of these animals was delayed. Complement was in particular required during the first days of infection. However, additionally, it seems to support protection at later stages. Migration of CD103+ dendritic cells from the infected lung to the draining lymph node-as prerequisite of antigen presentation-depended on C3 and C3aR and/or C5aR. Our results provide unique mechanistic insight in various aspects of complement-dependent immune responses under almost identical, rather physiological experimental conditions. Our study contributes to an improved understanding of the role of complement, and C3a in particular, in infections by intracellular bacteria.

Complement and Chlamydia psittaci: Non-Myeloid-Derived C3 Predominantly Induces Protective Adaptive Immune Responses in Mouse Lung Infection

Recent advances in complement research have revolutionized our understanding of its role in immune responses. The immunomodulatory features of complement in infections by intracellular pathogens, e.g., viruses, are attracting increasing attention. Thereby, local production and activation of complement by myeloid-derived cells seem to be crucial. We could recently show that C3, a key player of the complement cascade, is required for effective defense against the intracellular bacterium Chlamydia psittaci. Avian zoonotic strains of this pathogen cause life-threatening pneumonia with systemic spread in humans; closely related non-avian strains are responsible for less severe diseases of domestic animals with economic loss. To clarify how far myeloid- and non-myeloid cell-derived complement contributes to immune response and resulting protection against C. psittaci, adoptive bone marrow transfer experiments focusing on C3 were combined with challenge experiments using a non-avian (BSL 2) strain of this intracellular bacterium. Surprisingly, our data prove that for C. psittaci-induced pneumonia in mice, non-myeloid-derived, circulating/systemic C3 has a leading role in protection, in particular on the development of pathogen-specific T- and B- cell responses. In contrast, myeloid-derived and most likely locally produced C3 plays only a minor, mainly fine-tuning role. The work we present here describes authentic, although less pronounced, antigen directed immune responses.

Use of Chlamydial Elementary Bodies as Probes to Isolate Pathogen-Specific Human Monoclonal Antibodies

Chlamydia trachomatis is one of the most prevalent sexually transmitted infectious agents in the world and the leading cause of infectious blindness. The role of antibodies in the prevention and clearance of infection is still not fully understood, but the analysis of the immunoglobulin response to novel vaccine candidates is an important part of many of these studies. In this chapter, we describe a novel method to identify and isolate Chlamydia-specific memory B cells by fluorescence-activated cell sorting (FACS) using fluorescently labeled whole bacteria from cryopreserved human PBMC samples. This method allows for live single cells to be sorted for cell culture, in vitro assays, single-cell RNA sequencing, and cloning of paired heavy and light chains for recombinant monoclonal antibody production.

Chlamydia trachomatis CT229 Subverts Rab GTPase-Dependent CCV Trafficking Pathways to Promote Chlamydial Infection

Chlamydial infection requires the formation of a membrane-bound vacuole, termed the inclusion, that undergoes extensive interactions with select host organelles. The importance of the Inc protein CT229 in the formation and maintenance of the chlamydial inclusion was recently highlighted by studies demonstrating that its absence during infection results in reduced bacterial replication, premature inclusion lysis, and host cell death. Previous reports have indicated that CT229 binds Rab GTPases; however, the physiological implications of this interaction are unknown. Here, we show that CT229 regulates host multivesicular trafficking by recruiting multiple Rab GTPases and their cognate effectors to the inclusion. We demonstrate that CT229 specifically modulates clathrin-coated vesicle trafficking and regulates the trafficking of transferrin and the mannose-6-phosphate receptor, both of which are crucial for proper chlamydial development. This study highlights CT229 as a master regulator of multiple host vesicular trafficking pathways essential for chlamydial infection.

In vivo effect of bevacizumab-loaded albumin nanoparticles in the treatment of corneal neovascularization

Corneal neovascularization (CNV) is associated with different ocular pathologies, including infectious keratitis, trachoma or corneal trauma. Pharmacological treatments based on the topical application of anti-VEGF therapies have been shown to be effective in the treatment and prevention of CNV. The aim of this work was to evaluate the effect of bevacizumab-loaded albumin nanoparticles in a rat model of CNV. Bevacizumab-loaded nanoparticles, either "naked" (B-NP) or coated with PEG 35,000 (B-NP-PEG), were administered once a day in the eyes of animals (10 μL, 4 mg/mL every 24 h) during 7 days. Bevacizumab and dexamethasone were employed as controls and administered at the same dose every 12 h. At the end of the study, the area of the eye affected by neovascularization was about 2-times lower for animals treated with B-NP than with free bevacizumab. In the study, dexamethasone did not demonstrate an inhibitory effect on CNV at the employed dose. All of these results were confirmed by histopathological analysis, which clearly showed that eyes treated with nanoparticles displayed lower levels of fibrosis, inflammation and edema. In summary, the encapsulation of bevacizumab in human serum albumin nanoparticles improved its efficacy in an animal model of CNV.

Antibiotics for treating urogenital Chlamydia trachomatis infection in men and non-pregnant women

BACKGROUND

The genital infection caused by Chlamydia trachomatis (CT) is a common sexually transmitted infection (STI) globally. The infection is mainly asymptomatic in women, thus it can produce infertility and chronic pelvic pain. In men infection is mainly symptomatic, but can evolve to prostatitis. Clinical practice guidelines for CT urogenital infections do not give any specific recommendation about which antibiotic use as first option OBJECTIVES: To assess the efficacy and safety of antibiotic treatment for CT genital infection in men and non-pregnant women.

SEARCH METHODS

The Cochrane Sexually Transmitted Infections' (STI) Information Specialist developed the electronic searches in electronic databases (CENTRAL, MEDLINE, Embase and LILACS), and trials registers. We searched studies published from inception to June 2018.

SELECTION CRITERIA

We included parallel, randomised controlled trials (RCTs) of men, and sexually-active, non-pregnant women with CT infection (urethritis or uterine cervicitis or asymptomatic), diagnosed by cell culture for CT, nucleic acid amplification tests (NAAT) or antigen-based detection methods, who had been treated with any of the antibiotic regimens recommended by any of the updated to 2013 CT Guidelines.

DATA COLLECTION AND ANALYSIS

Four review authors screened evidence according to selection criteria and independently extracted data and assessed risk of bias. Two authors developed the 'Summary of findings' tables. We used a fixed-effect meta-analysis model for combining data where it was reasonable to assume that studies were estimating the same underlying treatment effect. We estimated the pooled risk ratio in order to establish the effects of the comparisons. Our primary outcomes were microbiological failure and adverse events, and our secondary outcomes were clinical failure, antimicrobial resistance and reinfection.

MAIN RESULTS

We selected 14 studies ( 2715 participants: 2147 (79.08%) men and 568 (20.92%) women). The studies were conducted mainly at STD clinics. Sample sizes ranged from 71 to 606 participants; follow-up was 29.7 days on average.For the comparison: azithromycin single dose versus doxycycline once or twice daily for 7 days, in men treated for CT, the risk of microbiological failure was higher in the azithromycin group (RR 2.45, 95% CI 1.36 to 4.41; participants = 821; studies = 9; moderate-quality evidence), but regarding clinical failure, the results showed that the effect is uncertain (RR 0.94, 95% CI 0.43 to 2,05; I² = 55%; participants = 525; studies = 3; low-quality evidence). Regarding adverse events (AE) in men there could be little or no difference between the antibiotics (RR 0.83, 95% CI 0.67 to 1.02; participants = 1424; studies = 6; low-quality evidence). About women treated for CT, the effect on microbiological failure was uncertain (RR = 1.71, 95% CI 0.48 to 6.16; participants = 338; studies = 5; very low-quality evidence). There were no studies assessing clinical failure or adverse events in women, however, we found that azithromycin probably has fewer adverse events in both genders (RR 0.83, 95% CI 0.71 to 0.98; I² = 0%; participants = 2261; studies = 9; moderate-quality evidence).For the second comparison: doxycycline compared to ofloxacin, for men treated for CT the effect on microbiological failure was uncertain (RR 8.53, 95% CI 0.43 to 167.38, I² not applicable; participants = 80; studies = 2; very low-quality evidence), as also it was on clinical failure (RR 0.85, 95% CI 0.28 to 2.62; participants = 36; studies = 1; very low-quality evidence). The effect of in women on clinical failure was uncertain (RR 0.94, 95% CI 0.39 to 2.25; I² = 39%; participants = 127; studies = 2; very low-quality evidence).Regarding adverse events, the effect in both men and women was uncertain (RR 1.02 95% CI 0.66 to 1.55; participants = 339 studies = 3; very low-quality evidence). The effect on microbiological failure in women and in men and women together, the effect on microbiological failure was not estimable. The most frequently AE reported were not serious and of gastrointestinal origin.No studies assessed antimicrobial resistance or reinfection in either comparison.

AUTHORS' CONCLUSIONS

In men, regimens with azithromycin are probably less effective than doxycycline for microbiological failure, however, there might be little or no difference for clinical failure. For women, we are uncertain whether azithromycin compared to doxycycline increases the risk of microbiological failure. Azithromycin probably slightly reduces adverse events compared to doxycycline in men and women together but may have little difference in men alone. We are uncertain whether doxycycline compared to ofloxacin reduces microbiological failure in men or women alone, or men and women together, nor if it reduces clinical failure or adverse events in men or women.Based on the fact that women suffer mainly asymptomatic infections, and in order to test the effectiveness and safety of the current recommendations (azithromycin, doxycycline and ofloxacin), for CT infection, especially in low and middle income countries, future RCTs should be designed and conducted to include a large enough sample size of women, and with low risk of bias. It is also important that future RCTs include adherence, CT resistance to antibiotic regimens, and risk of reinfection as outcomes to be measured. In addition, it is important to conduct a network meta-analysis in order to evaluate all those studies that included in one arm only the current antibiotic treatments for CT infection that are recommended by the updated clinical practice guidelines.

Therapeutic effect of a Chlamydia pecorum recombinant major outer membrane protein vaccine on ocular disease in koalas (Phascolarctos cinereus)

Chlamydia pecorum is responsible for causing ocular infection and disease which can lead to blindness in koalas (Phascolarctos cinereus). Antibiotics are the current treatment for chlamydial infection and disease in koalas, however, they can be detrimental for the koala’s gastrointestinal tract microbiota and in severe cases, can lead to dysbiosis and death. In this study, we evaluated the therapeutic effects provided by a recombinant chlamydial major outer membrane protein (MOMP) vaccine on ocular disease in koalas. Koalas with ocular disease (unilateral or bilateral) were vaccinated and assessed for six weeks, evaluating any changes to the conjunctival tissue and discharge. Samples were collected pre- and post-vaccination to evaluate both humoral and cell-mediated immune responses. We further assessed the infecting C. pecorum genotype, host MHC class II alleles and presence of koala retrovirus type (KoRV-B). Our results clearly showed an improvement in the clinical ocular disease state of all seven koalas, post-vaccination. We observed increases in ocular mucosal IgA antibodies to whole C. pecorum elementary bodies, post-vaccination. We found that systemic cell-mediated immune responses to interferon-γ, interleukin-6 and interleukin-17A were not significantly predictive of ocular disease in koalas. Interestingly, one koala did not have as positive a clinical response (in one eye primarily) and this koala was infected with a C. pecorum genotype (E’) that was not used as part of the vaccine formula (MOMP genotypes A, F and G). The predominant MHC class II alleles identified were DAb*19, DAb*21 and DBb*05, with no two koalas identified with the same genetic sequence. Additionally, KoRV-B, which is associated with chlamydial disease outcome, was identified in two (29%) ocular diseased koalas, which still produced vaccine-induced immune responses and clinical ocular improvements post-vaccination. Our findings show promise for the use of a recombinant chlamydial MOMP vaccine for the therapeutic treatment of ocular disease in koalas.

Resveratrol Inhibits Propagation of Chlamydia trachomatis in McCoy Cells

Resveratrol (RESV), an antifungal compound from grapes and other plants, has a distinct ability to inhibit the Chlamydia (C.) trachomatis developmental cycle in McCoy cells, a classic cell line used for chlamydial research. Inoculation of C. trachomatis with increasing amounts of RESV (from 12.5 to 100 μM) gave a dose-dependent reduction in the number of infected McCoy cells visualized by using monoclonal antibodies against chlamydial lipopolysaccharide. A similar trend has been observed with immunoassay for major outer membrane protein (MOMP). Furthermore, there was a step-wise reduction in the number of C. trachomatis infective progenies caused by the increasing concentrations of RESV. The ability of RESV to arrest C. trachomatis growth in McCoy cells was confirmed by a nucleic acid amplification protocol which revealed dose-dependent changes in mRNAs for different genes of chlamydial developmental cycle (euo, incA, and omcB). Although the precise nature of the antichlamydial activity of RESV is yet to be determined and evaluated in future studies, the observed effect of RESV on C. trachomatis infection was not related to its potential effect on attachment/entry of the pathogen into eukaryotic cells or RESV toxicity to McCoy cells. Similar inhibitory effect was shown for C. pneumoniae and C. muridarum.

Chlamydia trachomatis and its interaction with the cellular retromer

Chlamydia trachomatis is an important human pathogen. This obligate intracellular bacterium grows inside the eukaryotic cell in a membrane-bound compartment, the inclusion. Recent global approaches describe the interactions of C. trachomatis with its host cell and indicate the inclusion is an intracellular trafficking hub embedded into the cellular vesicular trafficking pathways recruiting subunits of the retromer protein complex of the host cell. Here we review these recent developments in deciphering Chlamydia-host cell interactions with emphasis on the role of the retromer complex.