Treatment challenges for urogenital and anorectal Chlamydia trachomatis

Chlamydia muridarum mutant CM-pGP3S as a novel attenuated live rectal vaccine protects against genital tract infection

Introduction

Chlamydia trachomatis (CT) is a major sexually transmitted pathogen with severe complications. Using Chlamydia muridarum (CM) as a model, this study evaluates the attenuated mutant Chlamydia muridarum (CM-pGP3S) as a novel rectal vaccine to protect against genital tract infection and pathology.

Methods

Female C57BL/6 mice were rectally immunized with low (1×103), middle (1×105), or high (1×107) doses of CM-pGP3S. Mice were challenged intravaginally with wild-type Chlamydia muridarum 63 days post-immunization. Protection was assessed via genital Chlamydia shedding, hydrosalpinx incidence (gross/histopathology), serum IgG, fecal IgA, and T cell responses. Gut microbiota stability was analyzed using qPCR.

Results

CM-pGP3S immunization significantly reduced CM-WT genital shedding duration (3-7 days vs. 21 days in controls, p < 0.01) and hydrosalpinx incidence (0% vs. 80% in controls, p < 0.01). Elevated systemic and mucosal immunity were observed, including higher serum IgG (1:100-1:1600 dilutions, p < 0.05-0.01) and fecal IgA (p < 0.05-0.01). CD4+ and CD8+ T cells exhibited increased IFN-γ (p < 0.01), while CD8+ T cells showed elevated TNF-α and IL-2 (p < 0.05). No colitis or significant gut microbiota disruption occurred post-immunization.

Discussion

Rectal CM-pGP3S vaccination induces robust transmucosal immunity, protecting against genital Chlamydia infection and pathology without gastrointestinal adverse effects. This highlights its potential as a safe and effective mucosal vaccine strategy to combat CT genital tract infections.

2025 European guideline on the management of Chlamydia trachomatis infections

Sexually transmitted Chlamydia trachomatis infections remain common globally and most frequently are asymptomatic. The 2025 European C. trachomatis guideline provides up-to-date guidance regarding indications for testing and treatment of C. trachomatis infections. It includes advice on urogenital and extragenital C. trachomatis testing including the use of self-collected specimens; recommendation to use only validated NAATs for diagnosis; and recommendation to treat all C. trachomatis infections with doxycycline as first line in preference to single-dose azithromycin regimens. The absence of evidence and limited value of broad screening in asymptomatic populations for C. trachomatis infections is also discussed.

Treatment of Chlamydia and Gonorrhea in Primary Care and Its Patient-Level Variation: An American Family Cohort Study

PURPOSE

Chlamydia and gonorrhea are the 2 most common bacterial sexually transmitted infections in the United States. Nonadherence to the Centers for Disease Control and Prevention treatment guidelines remains a concern. We examined how well chlamydia and gonorrhea treatment in primary care settings adhered to guidelines.

METHODS

We used electronic health records from the PRIME registry to identify patients with diagnosis codes or positive test results for chlamydia and/or gonorrhea from 2018 to 2022. Outcomes were the first dates of antibiotic administered within 30 days after a positive test result for the infection. Descriptive statistics were calculated for patient sociodemographic characteristics. We used a multivariate parametric accelerated failure time analysis with shared frailty modeling to assess associations between these characteristics and time to treatment.

RESULTS

We identified 6,678 cases of chlamydia confirmed by a positive test and 2,206 cases of gonorrhea confirmed by a positive test; 75.3% and 69.6% of these cases, respectively, were treated. Females, individuals aged 10-29 years, suburban dwellers, and patients with chlamydia-gonorrhea coinfection had higher treatment rates than comparator groups. Chlamydia was infrequently treated with the recommended antibiotic, doxycycline (14.0% of cases), and gonorrhea was infrequently treated with the recommended antibiotic, ceftriaxone (38.7% of cases). Time to treatment of chlamydia was longer for patients aged 50-59 years (time ratio relative to those aged 20-29 years = 1.61; 95% CI, 1.12-2.30) and for non-Hispanic Black patients (time ratio relative to White patients = 1.17; 95% CI, 1.04-1.33).

CONCLUSIONS

Guideline adherence remains suboptimal for chlamydia and gonorrhea treatment across primary care practices. Efforts are needed to develop interventions to improve quality of care for these sexually transmitted infections.

Efficacy of a Novel Affitoxin Targeting Major Outer Membrane Protein Against Chlamydia trachomatis In Vitro and In Vivo

Targeted therapy is an attractive approach for treating infectious diseases. Affibody molecules have similar capability to antibodies that facilitate molecular recognition in both diagnostic and therapeutic applications. Targeting major outer membrane protein (MOMP) for treating infection of Chlamydia trachomatis, one of the most common sexually transmitted pathogens, is a promising therapeutic approach. Previously, we have reported a MOMP-specific affibody (ZMOMP:461) from phage display library. Here, we first fused it with modified Pseudomonas exotoxin (PE38KDEL) and a cell-penetrating peptide (CPP) to develop an affitoxin, Z461X-CPP. We then verified the addition of both toxin and CPPs that did not affect the affinitive capability of ZMOMP:461 to MOMP. Upon uptake by C trachomatis-infected cells, Z461X-CPP induced cell apoptosis in vitro. In an animal model, Z461X significantly shortened the duration of C trachomatis infection and prevented pathological damage in the mouse reproductive system. These findings provide compelling evidence that the MOMP-specific affitoxin has great potential for targeting therapy of C trachomatis infection.

Chlamydia infection with vaccination asymptotic for qualitative and chaotic analysis using the generalized fractal fractional operator

In this work, we solve a system of fractional differential equations utilizing a Mittag-Leffler type kernel through a fractal fractional operator with two fractal and fractional orders. A six-chamber model with a single source of chlamydia is studied using the concept of fractal fractional derivatives with nonsingular and nonlocal fading memory. The fractal fractional model of the Chlamydia system can be solved by using the characteristics of a non-decreasing and compact mapping. A suggested model with the Lipschitz criteria and linear growth is studied both qualitatively and quantitatively, taking into account boundedness, uniqueness, and positive solutions at equilibrium points with Leray-Schauder results under time scale concepts. We examined the framework of local and global stability and insight into Lyapunov function properties for the infectious disease model. Chaos Control will employ the regulate for linear responses approach to stabilize the system following its equilibrium points. This will take into consideration a fractional order framework with a managed design, where solutions are bounded in the feasible domain and have a greater impact at the lower minimum infectious rate. To illustrate the implications of fractional and fractal dimensions with varying interest rate values through simulations with Newton's polynomial method under the Mittag-Lefller kernel. Additionally, a comparative analysis of results is also derived by employing power and exponential decay kernels at various fractional orders.

High prevalence and incidence of gonorrhoea and chlamydia in young women eligible for HIV pre-exposure prophylaxis in South Africa and Zimbabwe: results from the HPTN 082 trial

INTRODUCTION

We investigated the prevalence, incidence and factors associated with sexually transmitted infections (STIs) among young African women seeking HIV pre-exposure prophylaxis (PrEP).

METHODS

HPTN 082 was a prospective, open-label PrEP study enrolling HIV-negative sexually active women aged 16-25 years in Cape Town and Johannesburg, South Africa, and Harare, Zimbabwe. Endocervical swabs from enrolment, months 6 and 12 were tested for Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) by nucleic acid amplification, and Trichomonas vaginalis (TV) by a rapid test. Intracellular tenofovir-diphosphate (TFV-DP) concentrations in dried blood spots were measured at months 6 and 12. Associations between risk characteristics and STI outcomes were assessed using Poisson regression.

RESULTS

Of 451 enrolled participants, 55% had an STI detected at least once. CT incidence was 27.8 per 100 person-years (py) (95% CI 23.1, 33.2), GC incidence was 11.4 per 100 py (95% CI 8.5, 15.0) and TV incidence was 6.7 per 100 py (95% CI 4.5, 9.5). 66% of incident infections were diagnosed in women uninfected at baseline. Baseline cervical infection (GC or CT) risk was highest in Cape Town (relative risk (RR) 2.38, 95% CI 1.35, 4.19) and in those not living with family (RR 1.87, 95% 1.13, 3.08); condom use was protective (RR 0.67, 95% CI 0.45, 0.99). Incident CT was associated with baseline CT (RR 2.01; 95% CI 1.28, 3.15) and increasing depression score (RR 1.05; 95% CI 1.01, 1.09). Incident GC was higher in Cape Town (RR 2.40; 95% CI 1.18, 4.90) and in participants with high PrEP adherence (TFV-DP concentrations ≥700 fmol/punch) (RR 2.04 95% CI 1.02, 4.08).

CONCLUSION

Adolescent girls and young women seeking PrEP have a high prevalence and incidence of curable STIs. Alternatives to syndromic management for diagnosis and treatment are needed to reduce the burden of STIs in this population.

TRIAL REGISTRATION NUMBER

NCT02732730.

The effect of screening on the health burden of chlamydia: An evaluation of compartmental models based on person-days of infection

Sexually transmitted diseases (STDs) are detrimental to the health and economic well-being of society. Consequently, predicting outbreaks and identifying effective disease interventions through epidemiological tools, such as compartmental models, is of the utmost importance. Unfortunately, the ordinary differential equation compartmental models attributed to the work of Kermack and McKendrick require a duration of infection that follows the exponential or Erlang distribution, despite the biological invalidity of such assumptions. As these assumptions negatively impact the quality of predictions, alternative approaches are required that capture how the variability in the duration of infection affects the trajectory of disease and the evaluation of disease interventions. So, we apply a new family of ordinary differential equation compartmental models based on the quantity person-days of infection to predict the trajectory of disease. Importantly, this new family of models features non-exponential and non-Erlang duration of infection distributions without requiring more complex integral and integrodifferential equation compartmental model formulations. As proof of concept, we calibrate our model to recent trends of chlamydia incidence in the U.S. and utilize a novel duration of infection distribution that features periodic hazard rates. We then evaluate how increasing STD screening rates alter predictions of incidence and disability adjusted life-years over a five-year horizon. Our findings illustrate that our family of compartmental models provides a better fit to chlamydia incidence trends than traditional compartmental models, based on Akaike information criterion. They also show new asymptomatic and symptomatic infections of chlamydia peak over drastically different time frames and that increasing the annual STD screening rates from 35% to 40%-70% would annually avert 6.1-40.3 incidence while saving 1.68-11.14 disability adjusted life-years per 1000 people. This suggests increasing the STD screening rate in the U.S. would greatly aid in ongoing public health efforts to curtail the rising trends in preventable STDs.

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

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

Role of fractional derivatives in the mathematical modeling of the transmission of Chlamydia in the United States from 1989 to 2019

Nowadays, the mathematical modeling of infectious diseases is a big trend worldwide. The mathematical models help us to forecast future outbreaks of diseases in the presence of present data. In this article, we represent a model of the transmission of Chlamydia in the United States by using data from 1989 to 2019. In the formulation of the model, we used integer and fractional derivatives. Several graphs are plotted for the various possible cases of the given parameters. The aim of this paper is to justify how the mathematical models in terms of fractional derivatives have more degree of freedom to explore disease dynamics for a particular data set and capture memory effects. The separate parameter estimation for each value of the fractional order increases the novelty of this work. The use of a real-data set of Chlamydia in the United States makes this study more visible and important to the literature.

Rhein inhibits Chlamydia trachomatis infection by regulating pathogen-host cell

The global incidence of genital Chlamydia trachomatis infection increased rapidly as the primary available treatment of C. trachomatis infection being the use of antibiotics. However, the development of antibiotics resistant stain and other treatment failures are often observed in patients. Consequently, novel therapeutics are urgently required. Rhein is a monomer derivative of anthraquinone compounds with an anti-infection activity. This study investigated the effects of rhein on treating C. trachomatis infection. Rhein showed significant inhibitory effects on the growth of C. trachomatis in multiple serovars of C. trachomatis, including D, E, F and L1, and in various host cells, including HeLa, McCoy and Vero. Rhein could not directly inactivate C. trachomatis but could inhibit the growth of C. trachomatis by regulating pathogen-host cell interactions. Combined with azithromycin, the inhibitory effect of rehin was synergistic both in vitro and in vivo. Together these findings suggest that rhein could be developed for the treatment of C. trachomatis infections.

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.

Metagenomic Shotgun Sequencing of Endocervical, Vaginal, and Rectal Samples among Fijian Women with and without Chlamydia trachomatis Reveals Disparate Microbial Populations and Function across Anatomic Sites: a Pilot Study

Chlamydia trachomatis is a sexually transmitted pathogen and a global public health concern. Little is known about the microbial composition and function across endocervical, vaginal, and rectal microbiomes in the context of C. trachomatis infection. We evaluated the microbiomes of 10 age-matched high-risk Fijian women with and without C. trachomatis using metagenomic shotgun sequencing (MSS). Lactobacillus iners and Lactobacillus crispatus dominated the vagina and endocervix of uninfected women. Species often found in higher relative abundance in bacterial vaginosis (BV)-Mageeibacillus indolicus, Prevotella spp., Sneathia spp., Gardnerella vaginalis, and Veillonellaceae spp.-were dominant in C. trachomatis-infected women. This combination of BV pathogens was unique to Pacific Islanders compared to previously studied groups. The C. trachomatis-infected endocervix had a higher diversity of microbiota and microbial profiles that were somewhat different from those of the vagina. However, community state type III (CST-III) and CST-IV predominated, reflecting pathogenic microbiota regardless of C. trachomatis infection status. Rectal microbiomes were dominated by Prevotella and Bacteroides, although four women had unique microbiomes with Gardnerella, Akkermansia, Bifidobacterium, and Brachyspira. A high level of microbial similarity across microbiomes in two C. trachomatis-infected women suggested intragenitorectal transmission. A number of metabolic pathways in the endocervix, driven by BV pathogens and C. trachomatis to meet nutritional requirements for survival/growth, 5-fold higher than that in the vagina indicated that endocervical microbial functions are likely more diverse and complex than those in the vagina. Our novel findings provide the impetus for larger prospective studies to interrogate microbial/microbiome interactions that promote C. trachomatis infection and better define the unique genitorectal microbiomes of Pacific Islanders. IMPORTANCE Chlamydia trachomatis is the primary cause of bacterial sexually transmitted infections worldwide, with a disturbing increase in annual rates. While there is a plethora of data on healthy and pathogenic vaginal microbiomes-defining microbial profiles and associations with sexually transmitted infections (STIs)-far fewer studies have similarly examined the endocervix or rectum. Further, vulnerable populations, such as Pacific Islanders, remain underrepresented in research. We investigated the microbial composition, structure, and function of these anatomic microbiomes using metagenomic shotgun sequencing among a Fijian cohort. We found, primarily among C. trachomatis-infected women, unique microbial profiles in endocervical, vaginal, and rectal microbiomes with an increased diversity and more complex microbial pathways in endocervical than vaginal microbiomes. Similarities in microbiome composition across sites for some women suggested intragenitorectal transmission. These novel insights into genitorectal microbiomes and their purported function require prospective studies to better define Pacific Islander microbiomes and microbial/microbiome interactions that promote C. trachomatis infection.

Direct assessment of possible mutations in the 23S rRNA gene encoding macrolide resistance in Chlamydia trachomatis

Reports of potential treatment failure have raised particular concerns regarding the efficacy of the single dose azithromycin regimen in the treatment of urogenital and anorectal Chlamydia trachomatis (CT) infections. Several factors have been suggested, including heterotypic resistance. Antimicrobial susceptibility testing in CT requires cell culture with serial dilutions of antibiotics, which is laborious and for which there is no standardized testing methodology. One method to partly overcome these difficulties would be to use a genotypic resistance assay, however most current available assays do still require prior CT culture. In order to facilitate the assessment of genotypic resistance directly from clinical samples, without the need for prior culture, the aim of this study was to develop a CT specific PCR assay for the assessment of resistance associated mutations (RAMs) in the 23S rRNA gene, and to evaluate a sample of clinical cases in which CT PCR’s remained positive during follow-up despite azithromycin treatment. Neither the in silico analysis nor the analytical specificity testing demonstrated clinically relevant cross-reactivity with other bacterial species. These results in conjunction with the analytical sensitivity demonstrating consistent CT 23S rRNA gene detection in the range of 10e3 IFU/mL, exemplify the assay’s apt performance. Although no known macrolide RAMs were detected in the clinical cases, the described assay allows future culture independent macrolide RAM surveillance in CT, and increases accessibility for other laboratories to engage in screening.

Epidemiology of symptomatic infective anoproctitis in a population of men having sex with men (MSM)

PURPOSE

Anoproctitis due to Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are Sexual Transmitted Infections (STIs) reported in MSM population. This study describes clinical and microbiological epidemiology of infective anoproctitis in MSM population.

METHODS

All patients with symptomatic anoproctitis consulting at the proctology Institute of Saint-Joseph's Hospital, Paris, were included. Detection of CT/NG was performed by PCR GeneXpert^R and other STIs pathogens Mycoplasma sp., HSV, CMV and T. pallidum were detected by multiplex PCR Allplex (mPCR).

RESULTS

Symptoms most frequently reported were pain, rectal bleeding and purulent flow in 66%, 52% and 49% of cases, respectively. On the 311 rectal samples collected, 171 (55.2%) were positive to CT/NG. Among the 194 used for mPCR, 148 were positive to STIs pathogens (76.2%) including 106 samples (71.6%) positive in coinfections. Among NG infections, 22.6% of the strains were resistant to azithromycin and 26.8% to tetracyclines.

CONCLUSIONS

Anorectal infections in this MSM population showed a high prevalence of not only CT/NG but also other pathogens involved in STIs. The high level of coinfections confirms the requirement of accurate PCR tests to improve diagnosis. This study describing increasing antibiotic resistances for NG strains confirms the updating of international guidelines on antibiotic treatments recommendations.

In Vitro and In Vivo Activity of (Trifluoromethyl)pyridines as Anti-Chlamydia trachomatis Agents

Chlamydia trachomatis is the leading pathogen in sexually transmitted bacterial infections across the globe. The development of a selective treatment against this pathogen could be an attractive therapeutic option that will reduce the overuse of broad-spectrum antibiotics. Previously, we reported some sulfonylpyridine-based compounds that showed selectivity against C. trachomatis. Here, we describe a set of related compounds that display enhanced anti-chlamydial potency when compared to our early leads. We found that the active molecules are bactericidal and have no impact on Staphylococcus aureus or Escherichia coli strains. Importantly, the molecules were not toxic to mammalian cells. Furthermore, a combination of molecule 20 (the most active molecule) and azithromycin at subinhibitory concentrations acted synergistically to inhibit chlamydial growth. Molecule 20 also eradicated Chlamydia in a 3D infection model and accelerated the recovery of Chlamydia-infected mice. This work presents compounds that could be further developed to be used alone or in combination with existing treatment regimens against chlamydial infections.

Inhibition of the futalosine pathway for menaquinone biosynthesis suppresses Chlamydia trachomatis infection

Chlamydia trachomatis, an obligate intracellular bacterium with limited metabolic capabilities, possesses the futalosine pathway for menaquinone biosynthesis. Futalosine pathway enzymes have promise as narrow-spectrum antibiotic targets, but the activity and essentiality of chlamydial menaquinone biosynthesis have yet to be established. In this work, menaquinone-7 (MK-7) was identified as a C. trachomatis-produced quinone through liquid chromatography-tandem mass spectrometry. An immunofluorescence-based assay revealed that treatment of C. trachomatis-infected HeLa cells with the futalosine pathway inhibitor docosahexaenoic acid (DHA) reduced inclusion number, inclusion size, and infectious progeny. Supplementation with MK-7 nanoparticles rescued the effect of DHA on inclusion number, indicating that the futalosine pathway is a target of DHA in this system. These results open the door for menaquinone biosynthesis inhibitors to be pursued in antichlamydial development.

How accurate is presumptive Chlamydia trachomatis treatment? A 6-month clinical audit of a walk-in sexual health service

Background Chlamydia trachomatis (chlamydia) is highly prevalent and is an important sexually transmitted infection as it can lead to increased risk of HIV seroconversion; and if left untreated, can cause infertility in women. Clinical guidelines recommend treating chlamydia presumptively when presenting symptomatically; however, clinicians are now questioning this due to increasing prevalence of antimicrobial resistance. Methods To determine the accuracy of presumptive chlamydia treatment practices at a walk-in sexual health service in regional Australia, we audited all same-day screen and treat presentations prescribed azithromycin over a 6-month period in 2018. Results A total of 325 cases were included in the analysis. Over half (54%) the presentations returned negative pathology for all pathogens investigated. One quarter (25%) of presentations were positive for chlamydia, and (4%) reported a dual infection. A further one fifth (20%) were negative for chlamydia but positive for another pathogen. More symptomatic males than females returned positive pathology for chlamydia (8% vs 4%). Conclusions While presumptive treatment is recommended in the current guidelines, our findings indicate this resulted in over-treatment. Considering the increasing resistance patterns for Mycoplasma genitalium, which include azithromycin, presumptive treatments need to balance immediate client care needs against long-term community antimicrobial resistance outcomes. This internal audit provided a feedback mechanism to the walk-in sexual service, enabling modification of practices to provide more precise, individual clinical care within the bounds of current STI guidelines, while balancing wider the objectives of antimicrobial stewardship.

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

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

Analysis of chlamydia contacts and the look-back interval at a UK sexual health clinic

Guidance on contact tracing in Chlamydia trachomatis (CT) is limited. CT contacts data over 12 months (1 December 2018-29 November 2019) at a UK sexual health clinic were analysed to determine the appropriateness of the currently recommended six-month 'look-back' interval. Age and sex of CT contacts were associated with clinical outcomes. Subgroups of 100 CT positive/negative contacts (each N = 100) were randomly selected. The relationship between time since sexual intercourse with the index case (Last Sexual Intercourse; LSI) and CT positivity was examined; suitability of varying look-back intervals was explored. Of 891 CT contacts (mean age = 25.0 years, 66.2% men), 66.9% tested positive for CT. Positive CT contacts were significantly younger (23.8 ± 6.8 years vs. 27.4 ± 9.1, p < 0.001) and more often women (36.4% vs. 28.5%, p = 0.018) than negative contacts. In the subgroups, the Mann-Whitney U test revealed no significant difference between the LSI of positive and negative contacts (p = 0.081). 95% of positive CT contacts (N = 82) were captured within a hypothetical three-month look-back interval. While most CT positive contacts were captured within three months, they appeared to remain proportionately represented beyond this point. Although this supports current guidelines, further research should investigate whether CT contacts involved in longer look-back intervals may require disproportionately greater resources to trace.

Chlamydia trachomatis glyceraldehyde 3-phosphate dehydrogenase: Enzyme kinetics, high-resolution crystal structure, and plasminogen binding

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is an evolutionarily conserved essential enzyme in the glycolytic pathway. GAPDH is also involved in a wide spectrum of non-catalytic cellular 'moonlighting' functions. Bacterial surface-associated GAPDHs engage in many host interactions that aid in colonization, pathogenesis, and virulence. We have structurally and functionally characterized the recombinant GAPDH of the obligate intracellular bacteria Chlamydia trachomatis, the leading cause of sexually transmitted bacterial and ocular infections. Contrary to earlier speculations, recent data confirm the presence of glucose-catabolizing enzymes including GAPDH in both stages of the biphasic life cycle of the bacterium. The high-resolution crystal structure described here provides a close-up view of the enzyme's active site and surface topology and reveals two chemically modified cysteine residues. Moreover, we show for the first time that purified C. trachomatis GAPDH binds to human plasminogen and plasmin. Based on the versatility of GAPDH's functions, data presented here emphasize the need for investigating the Chlamydiae GAPDH's involvement in biological functions beyond energy metabolism.

Optimising treatments for sexually transmitted infections: surveillance, pharmacokinetics and pharmacodynamics, therapeutic strategies, and molecular resistance prediction

Progressive antimicrobial resistance in Neisseria gonorrhoeae, Mycoplasma genitalium, and Trichomonas vaginalis has created a pressing need for treatment optimisations for sexually transmitted infections (STIs). In this Review, we aim to highlight urgent needs in global STI management, including: (1) improved surveillance to monitor antimicrobial resistance and clinical outcomes; (2) systematic pharmacokinetic and pharmacodynamic evaluations to ensure resistance suppression and bacterial eradication at all sites of infection; (3) development of novel, affordable antimicrobials; and (4) advancements in new molecular and point-of-care tests to detect antimicrobial resistance determinants. Antimicrobial resistance among STIs is a global public health crisis. Continuous efforts to develop novel antimicrobials will be essential, in addition to other public health interventions to reduce the global STI burden. Apart from prevention through safer sexual practices, the development of STI vaccines to prevent transmission is a crucial research priority.

Low-dose doxycycline induces Chlamydia trachomatis persistence in HeLa cells

Chlamydia persistence is a viable but non-replicative stage, induced by several sub-lethal stressor agents, including beta-lactam antibiotics. So far, no data about the connection between doxycycline and chlamydial persistence has been described in literature. We investigated the ability of doxycycline to induce C. trachomatis (CT) persistence in an in vitro model of epithelial cell infection (HeLa cells), comparing the results with the well-established model of penicillin-induced persistence. The effect of doxycycline was explored on 10 different CT strains by analysing (i) the presence of aberrant inclusions, (ii) chlamydial recovery, (iii) the expression of different chlamydial genes (omcB, euo, Ct110, Ct604, Ct755, HtrA) and (iv) the effects on epithelial cell viability. For each strain, the presence of foreign genomic islands responsible of tetracycline resistance was excluded. We found that low doses of doxycycline can induce a condition of CT persistence. For concentrations of doxycycline equal to 0.03-0.015 mg/L, CT inclusions are smaller and aberrant and CT cycle is characterized by the presence of viable but non-dividing RBs with the complete abolishment of chlamydial cytotoxic effect. Infectious EBs can be recovered after removal of the drug. During doxycycline-induced persistence, the expression of the late gene omcB is decreased, indicating the blocking of RB-to-EB conversion. Conversely, as for penicillin G, a significant up-regulation of the stress response HtrA gene is found in doxycycline-treated cells. This study provides a novel in vitro cell model to examine the characteristics of doxycycline-induced persistent CT infection.

Synthesis and Antichlamydial Activity of Molecules Based on Dysregulators of Cylindrical Proteases

Chlamydia trachomatis is the most common sexually transmitted bacterial disease globally and the leading cause of infertility and preventable infectious blindness (trachoma) in the world. Unfortunately, there is no FDA-approved treatment specific for chlamydial infections. We recently reported two sulfonylpyridines that halt the growth of the pathogen. Herein, we present a SAR of the sulfonylpyridine molecule by introducing substituents on the aromatic regions. Biological evaluation studies showed that several analogues can impair the growth of C. trachomatis without affecting host cell viability. The compounds did not kill other bacteria, indicating selectivity for Chlamydia. The compounds presented mild toxicity toward mammalian cell lines. The compounds were found to be nonmutagenic in a Drosophila melanogaster assay and exhibited a promising stability in both plasma and gastric fluid. The presented results indicate this scaffold is a promising starting point for the development of selective antichlamydial drugs.

High Interest in Syphilis Pre-exposure and Post-exposure Prophylaxis Among Gay, Bisexual and Other Men Who Have Sex With Men in Vancouver and Toronto

BACKGROUND

We assessed the acceptability of doxycycline-based syphilis pre-exposure and post-exposure prophylaxis (PrEP/PEP) as well as human immunodeficiency virus (HIV) PrEP/PEP in gay, bisexual, and other men who have sex with men (gbMSM).

METHODS

We recruited gbMSM from Toronto and Vancouver sexually transmitted infection (STI) clinics during routine visits from June 2018 to August 2018. We analyzed data using descriptive statistics and constructed multivariable logistic regression models for willingness to use syphilis and HIV PrEP and PEP respectively.

RESULTS

Among 424 participants (56.4% Toronto, 43.6% Vancouver), median (interquartile range [IQR]) age was 31.0 years (26.0-39.0 years), 61.7% had completed postsecondary education and 54.4% were white. Median (IQR) number of male partners in the past 6 months was 6.0 (3.0-13.0), and 18.2% had 1 or more prior syphilis diagnosis. 60.1%/44.1% indicated willingness to use syphilis PEP/PrEP; 36.6% were unwilling to use either. Among HIV-negative participants, 74.0% and 75.2% were willing to use HIV PrEP and PEP, respectively. Most participants were familiar with antibiotic resistance (89.0%) and agreed that syphilis rates are rising in Canada (68.2%), but only 55.4% believed they were at risk for syphilis. Agreement with the latter statement was associated with willingness to use syphilis PrEP (adjusted odds ratio [aOR], 1.6; 95% confidence interval [95%CI], 1.0-2.5), as was previous/existing HIV PrEP use (aOR, 2.2; 95% CI, 1.1-4.3) and being "very concerned" about STI acquisition (aOR, 1.9; 95% CI, 1.0-3.4). Odds of being willing to use syphilis PEP were higher in Toronto versus Vancouver (aOR, 2.0; 95% CI, 1.2-3.4) and increased with the number of different STIs previously diagnosed (aOR, 1.4; 95% CI, 1.2,1.7).

CONCLUSIONS

There is considerable interest in syphilis PrEP/PEP in gbMSM attending Toronto/Vancouver STI clinics.

Chlamydiae from Down Under: The Curious Cases of Chlamydial Infections in Australia

In Australia, the most researched and perhaps the most successful chlamydial species are the human pathogen Chlamydia trachomatis, animal pathogens Chlamydia pecorum and Chlamydia psittaci. C. trachomatis remains the leading cause of sexually transmitted infections in Australians and trachoma in Australian Indigenous populations. C. pecorum is globally recognised as the infamous koala and widespread livestock pathogen, whilst the avian C. psittaci is emerging as a horse pathogen posing zoonotic risks to humans. Certainly not innocuous, the human infections with Chlamydia pneumoniae seem to be less prevalent that other human chlamydial pathogens (namely C. trachomatis). Interestingly, the complete host range for C. pecorum and C. psittaci remains unknown, and infections by other chlamydial organisms in Australian domesticated and wildlife animals are understudied. Considering that chlamydial organisms can be encountered by either host at the human/animal interface, I review the most recent findings of chlamydial organisms infecting Australians, domesticated animals and native wildlife. Furthermore, I also provide commentary from leading Australian Chlamydia experts on challenges and future directions in the Chlamydia research field.

Insights into the Autoproteolytic Processing and Catalytic Mechanism of the Chlamydia trachomatis Virulence-Associated Protease CPAF

CPAF (chlamydial protease-like activity factor) is a Chlamydia trachomatis protease that is translocated into the host cytosol during infection. CPAF activity results in dampened host inflammation signaling, cytoskeletal remodeling, and suppressed neutrophil activation. Although CPAF is an emerging antivirulence target, its catalytic mechanism has been unexplored to date. Steady state kinetic parameters were obtained for recombinant CPAF with vimentin-derived peptide substrates using a high-performance liquid chromatography-based discontinuous assay (k_cat = 45 ± 0.6 s^-1; k_cat/K_m = 0.37 ± 0.02 μM^-1 s^-1) or a new fluorescence-based continuous assay (k_cat = 23 ± 0.7 s^-1; k_cat/K_m = 0.29 ± 0.03 μM^-1 s^-1). Residues H105, S499, E558, and newly identified D103 were found to be indispensable for autoproteolytic processing by mutagenesis, while participation of C500 was ruled out despite its proximity to the S499 nucleophile. Pre-steady state kinetics indicated a burst kinetic profile, with fast acylation (k_acyl = 110 ± 2 s^-1) followed by slower, partially rate-limiting deacylation (k_deacyl = 57 ± 1 s^-1). Both k_cat- and k_cat/K_m-pH profiles showed single acidic limb ionizations with pK_a values of 6.2 ± 0.1 and 6.5 ± 0.1, respectively. A forward solvent deuterium kinetic isotope effect of 2.6 ± 0.1 was observed for ^D₂Ok_cat^app, but a unity effect was found for ^D₂Ok_cat/K_m^app. The k_cat proton inventory was linear, indicating transfer of a single proton in the rate-determining transition state, most likely from H105. Collectively, these data provide support for the classification of CPAF as a serine protease and provide a mechanistic foundation for the future design of inhibitors.

Structure-based drug target prioritisation and rational drug design for targeting Chlamydia trachomatis eye infections

Chlamydia trachomatis (C.t) is a major causative of infectious blindness in world. It is a real challenge to combat Chlamydial infection as it is an intracellular pathogen. Hence, it is essential to determine the most potential targets of C.t in order to inhibit or suppress its virulence during its infectious phase. Thus, in this study, the highly expressed-cum-most essential genes reported through our earlier study were reprioritized by structure-based comparative binding site analysis with host proteome. Therefore, computational approaches involving molecular modelling, large-scale binding site prediction and comparison, molecular dynamics simulation studies were performed to narrow down the most potential targets. Furthermore, high-throughput virtual screening and ADMETox were also performed to identify potential hits that shall efficiently inhibit the prioritised targets. Hence, by this study we report Pyruvoyl-dependent arginine decarboxylase (PvlArgDC), DNA-repair protein (RecO) and porin (outer membrane protein) as the most viable targets of C.t which can be potentially targeted by compounds, NSC_13086, MFCD00276409, MFCD05662003, respectively. AbbreviationsC.tChlamydia trachomatisSTDSexually transmitted diseaseHTVSHigh-throughput virtual screeningADMEToxAbsorption, Distribution, Metabolism, Excretion and ToxicityPMPocketMatchMDMolecular Dynamics simulationSPStandard precisionXPExtra precisionMMGBSAMolecular mechanics energies combined with generalised Born and surface area continuum solvationOMPOuter membrane proteinPvlArgDCPyruvoyl-dependent arginine decarboxylaseRecORecombination protein O.Communicated by Ramaswamy H. Sarma.

Chlamydia treatment failure after repeat courses of azithromycin and doxycycline

A case is presented of a 22 year-old woman with genital Chlamydia trachomatis infection, which persisted for 8 months despite treatment with four 1g doses of azithromycin and both a 7-day and 14-day course of doxycycline. She denied any sexual contact during this time. Tests for other infections including extragenital sites were negative.

Recurrent/Intermittent Vaginal and Rectal Chlamydial Infection Following Treatment: A Prospective Cohort Study Among Female Sexually Transmitted Disease Clinic Patients

BACKGROUND

Rectal Chlamydia trachomatis (CT) is common among clinic-attending women, but little is known about clearance and health implications of rectal CT.

METHODS

At the municipal sexually transmitted disease clinic in Seattle, Washington, in 2017-2018, we enrolled women at high risk for urogenital CT into an 8-week prospective study. Women received standard CT treatment at enrollment. Women self-collected daily rectal and vaginal specimens for nucleic acid amplification tests (NAATs) and completed weekly sexual exposure diaries. We performed CT culture on the enrollment rectal specimen.

RESULTS

We enrolled 50 women; 13 (26%) tested positive for vaginal (n = 11) and/or rectal (n = 11) CT. Sixty percent of women with rectal CT per NAAT were also culture positive. Median time to CT clearance after azithromycin treatment was 8.0 days for vaginal CT and 7.0 days for rectal CT. Eight women with rectal CT at enrollment had at least 1 rectal CT-positive NAAT after clearance of the initial infection; none reported anal sex.

CONCLUSIONS

Most NAAT-positive rectal infections were culture positive, suggesting active infection. Time to NAAT clearance of rectal and genital tract CT was similar, and intermittent rectal CT positivity was common in the absence of anal sexual exposure. The cause of recurrent/intermittent rectal CT and the clinical implications of these infections require further study.

Phenotypic antimicrobial susceptibility testing of Chlamydia trachomatis isolates from patients with persistent or successfully treated infections

Objectives

Antimicrobial susceptibility data for Chlamydia trachomatis are lacking. Methodologies for susceptibility testing in C. trachomatis are not well-defined, standardized or performed routinely owing to its intracellular growth requirements. We sought to develop an assay for the in vitro susceptibility testing of C. trachomatis isolates from two patient cohorts with different clinical outcomes.

Methods

Twenty-four clinical isolates (11 from persistently infected and 13 from successfully treated patients) were overlaid with media containing two-fold serial dilutions of azithromycin or doxycycline. After incubation, aliquots were removed from the stock inoculum (SI) and each antimicrobial concentration for total RNA extraction, complementary DNA generation and real-time PCR. The MIC was defined as the lowest antimicrobial concentration where a 95% reduction in transcription was evident in comparison with the SI for each isolate.

Results

MICs of azithromycin were comparable for isolates from the two patient groups (82% ≤ 0.25 mg/L for persistently infected and 100% ≤ 0.25 mg/L for successfully treated patients). Doxycycline MICs were at least two-fold lower for isolates from the successfully treated patients (53.9% ≤ 0.064 mg/L) than for the persistently infected patients (100% ≥ 0.125 mg/L) (P = 0.006, Fisher's exact test). Overall, 96% of isolates gave reproducible MICs when re-tested.

Conclusions

A reproducible assay was developed for antimicrobial susceptibility testing of C. trachomatis. MICs of azithromycin were generally comparable for the two different patient groups. MICs of doxycycline were significantly higher in the persistently infected patients. However, interpretation of elevated MICs in C. trachomatis is extremely challenging in the absence of breakpoints, or wild-type and treatment failure MIC distribution data.

[Treatment of uncomplicated pelvic inflammatory disease: CNGOF and SPILF Pelvic Inflammatory Diseases Guidelines]

This review of the treatment of uncomplicated pelvic inflammatory disease (PID) focuses on the susceptibility profile of the main microbiological causes as well as on the advantages and inconvenients of relevant antibiotics. As bacterial resistance is expanding in the community, the rules of adequate antibiotic prescribing are integrated in the treatment proposals. While the pathogenic role of anaerobic bacteria in uncomplicated PID remains discussed, the choice to provide anaerobes coverage is proposed. Thus, the antibiotic treatment has to cover Chamydia trachomatis, Neisseria gonorrhoeae, anaerobes as well as Streptococcus spp, gram negative bacteria and the ermerging Mycoplasma genitalium. On the basis of published trials and good practice antibiotic usage, the ceftriaxone-doxycycline-metronidazole combination has been selected as the first line regimen. Fluoroquinolones (moxifloxacin alone, or levofloxacin or ofloxacin combined with metronidazole) are proposed as alternatives because of their ecological impact and their side effects leading to restricted usage. When fluoroquinolone are used, ceftriaxone should be added in case of possible sexually transmitted infection. When detected, M. genitalium should be treated by moxifloxacin. Moreover, this review highlights the need to better describe the microbiological epidemiology of uncomplicated PID in France or Europe.

High expression of IDO1 and TGF-β1 during recurrence and post infection clearance with Chlamydia trachomatis, are independent of host IFN-γ response

Background

Chlamydia trachomatis infections in women continue to be a major public health concern due to their high prevalence and consequent reproductive morbidities. While antibiotics are usually efficient to clear the Chlamydia, repeat infections are common and may contribute to pathological outcomes. Interferon-gamma (IFN-γ)-mediated immunity has been suggested to be protective against reinfection, and represent an important anti-chlamydial agent, primarily via the induction of indoleamine-2,3 dioxygenase 1 (IDO1) enzyme. IDO1 catalyzes the degradation of tryptophan, which can eliminate C. trachomatis infection in vitro. Here, we sought to measure IDO1 expression levels and related immune markers during different C. trachomatis infection statuses (repeated vs single infection vs post antibiotic treatment), in vitro and in vivo.

Methods

In this study, we measured the expression levels of IDO1 and immune regulatory markers, transforming growth factor β1 (TGF-β1) and forkhead box P3 (FoxP3), in vaginal swab samples of C. trachomatis-infected women, with either single or repeated infection. In addition, we used an in vitro co-culture model of endometrial carcinoma cell-line and peripheral blood mononuclear cells (PBMCs) to measure the same immune markers.

Results

We found that in women with repeated C. trachomatis infections vaginal IDO1 and TGF-β1 expression levels were significantly increased. Whereas, women who cleared their infection post antibiotic treatment, had increased levels of IDO1 and TGF-β1, as well as FoxP3. Similarly, using the in vitro model, we found significant upregulation of IDO1 and TGF-β1 levels in the co-culture infected with C. trachomatis. Furthermore, we found that in PBMCs infected with C. trachomatis there was a significant upregulation in IDO1 levels, which was independent of IFN-γ. In fact, C. trachomatis infection in PBMCs failed to induce IFN-γ levels in comparison to the uninfected culture.

Conclusions

Our data provide evidence for a regulatory immune response comprised of IDO1, TGF-β1 and FoxP3 in women post antibiotic treatment. In this study, we demonstrated a significant increase in IDO1 expression levels in response to C. trachomatis infection, both in vivo and in vitro, without elevated IFN-γ levels. This study implicates IDO1 and TGF-β1 as part of the immune response to repeated C. trachomatis infections, independently of IFN-γ.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3843-4) contains supplementary material, which is available to authorized users.

Mini Review: Antimicrobial Control of Chlamydial Infections in Animals: Current Practices and Issues

Chlamydia are a genus of successful obligate intracellular pathogens spread across humans, wildlife, and domesticated animals. The most common species reported in livestock in this genus are Chlamydia abortus, Chlamydia psittaci, Chlamydia suis, and Chlamydia pecorum. Chlamydial infections trigger a series of inflammatory disease-related sequelae including arthritis, conjunctivitis, pneumonia, and abortion. Other bacteria in the phylum Chlamydiae have also been reported in livestock and wildlife but their impact on animal health is less clear. Control of chlamydial infections relies on the use of macrolides, fluoroquinolones, and tetracyclines. Tetracycline resistance (TET^R) reported for porcine C. suis strains in association with the use of tetracycline feed is a potentially significant concern given experimental evidence highlighting that the genetic elements inferring TET^R may be horizontally transferred to other chlamydial species. As documented in human Chlamydia trachomatis infections, relapse of infections, bacterial shedding post-antibiotic treatment, and disease progression despite chlamydial clearance in animals have also been reported. The identification of novel chlamydiae as well as new animal hosts for previously described chlamydial pathogens should place a renewed emphasis on basic in vivo studies to demonstrate the efficacy of existing and new antimicrobial treatment regimes. Building on recent reviews of antimicrobials limited to C. trachomatis and C. suis, this review will explore the use of antimicrobials, the evidence and factors that influence the treatment failure of chlamydial infections in animals and the future directions in the control of these important veterinary pathogens.

Randomized, open-label, multicenter study of azithromycin compared with doxycycline for treating anorectal Chlamydia trachomatis infection concomitant to a vaginal infection (CHLAZIDOXY study)

BACKGROUND

Chlamydia trachomatis can lead to a persistent infection in the lower gastrointestinal tract, suggesting a potential role of autoinoculation of cervical chlamydial infection from the rectal site, contributing to repeat infections. Moreover, around 75% of women with urogenital C. trachomatis have concurrent anorectal infection. Current treatment guidelines for urogenital C. trachomatis infection recommend either a single 1 g dose of azithromycin or doxycycline 100 mg twice daily for 7 days. Doxycycline appears to be more effective in treating anorectal infections as suggested in a population of men who have sex with men, but no randomized controlled trial (RCT) had directly compared azithromycin with doxycycline for the treatment of rectal infections. We propose an open-label RCT to compare the microbial cure obtained with a single 1 g dose of azithromycin versus 100 mg of doxycycline twice daily for 7 days, for the treatment of anorectal C. trachomatis infection concurrent to urogenital infection in women.

METHODS AND STUDY DESIGN

A total of 460 women with C. trachomatis urogenital infection will be enrolled in the study. Women will be asked to provide self-collected anorectal swabs and will be randomized to receive either a 1 g single dose of azithromycin or doxycycline 100 mg twice daily for 7 days. Clinical and biological data will be collected and patients will complete questionnaires about their sexual behavior. The primary outcome is the microbial cure rate, defined as a C. trachomatis negative nucleic acid amplification test (NAAT) result in the anorectal specimens 6 weeks after treatment initiation among women with a C. trachomatis positive urogenital and anorectal NAAT result at the baseline. The secondary outcome is autoinoculation from the rectum to the vagina, which will be evaluated based on the number of women with the same C. trachomatis genotype profile that will be identified in an anorectal-positive specimen obtained 6 weeks after treatment initiation and in a vaginal-positive specimen obtained four months after treatment.

DISCUSSION

The results of this trial will establish which treatment is more efficacious against anorectal infection and could affect recommendations for the treatment of urogenital C. trachomatis infection, taking into account concurrent anorectal infection.

TRIAL REGISTRATION NUMBERS

EudraCT number: 2017-002595-15. CLINICALTRIALS.

GOV IDENTIFIER

NCT03532464. Date of registration: May 31, 2018.

WORLD HEALTH ORGANISATION INTERNATIONAL CLINICAL TRIALS REGISTRY

NTC03532464. Secondary ID: CHUBX 2016/26. Date of registration: May 09, 2018.

Biofilm in Genital Ecosystem: A Potential Risk Factor for Chlamydia trachomatis Infection

In healthy women, the cervicovaginal microbiota is mostly populated by Lactobacillus spp., the main host defense factor of the female genital tract. In addition to Lactobacilli, other microorganisms populate the cervicovaginal microbiota, like Candida spp. and Gardnerella vaginalis. The overgrowth of Candida spp. or G. vaginalis, known as biofilm-producing microorganisms in the genital ecosystem, may lead to microbial dysbiosis that increases the risk of acquiring sexually transmitted infections, like Chlamydia trachomatis. C. trachomatis, the leading cause of bacterial sexually transmitted diseases, is still considered an important public health problem worldwide because of the impact of asymptomatic infections on long-term reproductive sequelae, including pelvic inflammatory disease and infertility. The aim of our study was to investigate the interaction between C. trachomatis and the biofilm produced by Candida albicans or Gardnerella vaginalis, evaluating whether the biofilm can harbor C. trachomatis and influence its survival as well as its infectious properties. In order to do so, we developed an in vitro coculture transwell-based biofilm model. Our findings proved, for the first time, that C. trachomatis, an intracellular obligate pathogen, survived, for up to 72 hours after exposure, inside the biofilm produced by C. albicans or G. vaginalis, retaining its infectious properties, as evidenced by the typical chlamydial inclusions observed in the cell monolayer (chlamydial inclusion-forming units at 72 h: 9255 ± 1139 and 9873 ± 1015, respectively). In conclusion, our results suggest that the biofilm related to Candida or Gardnerella genital infections may act as a reservoir of C. trachomatis and, thus, contribute to the transmission of the infection in the population as well as to its dissemination into the upper genital tract, increasing the risk of developing severe reproductive sequelae.

Non-standard treatment for uncomplicated Chlamydia trachomatis urogenital infections: a systematic review

OBJECTIVES

To review the literature for non-standard treatment options for uncomplicated Chlamydia trachomatis (CT) infections in adolescents and adults.

DESIGN

Systematic review.

DATA SOURCES

Ovid MEDLINE/PubMed, Ovid EMBASE, Cochrane Trials & Systematic Review Databases, CINAHL Plus with Full Text, Web of Science Core Collection, Scopus, ProQuest Dissertations & Theses Global, ClinicalTrials.gov and Health Canada Trials Database were searched for studies in English or French from 1 January 2006 to 6 August 2017. Keywords included CT, anti-infective or anti-bacterial agents, therapy/pharmacotherapy/management.

REVIEW METHODS

Included were primary research studies. Outcome measures included clinical or microbiological cure, treatment failure and adverse events. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were assessed for risk of bias using the Revised Cochrane Risk of Bias V.2.0 tool for randomised and the Newcastle-Ottawa Quality Assessment Scale for non-randomised studies.

FUNDING SOURCE

Public Health Agency of Canada.

RESULTS

Of the 6899 records identified through the database search, 11 studies were included. One randomised controlled trial reported that delayed release doxycycline was non-inferior to azithromycin. Two studies examined higher doses of azithromycin but reported no additional benefit. One study looked at a 5-day azithromycin treatment regimen and reported a high cure rate. Two studies reported efficacy of sitafloxacin, and a single study supports the use of levofloxacin. Two phase 2 studies reported efficacy of single-dose rifalazil in both men and women. Only one retrospective study was identified that examined treatment in pregnant women and reported that efficacy with single-dose azithromycin exceeded that of amoxicillin and erythromycin. A single study examining the efficacy of a beta-lactam antibiotic was stopped early due to high treatment failures.

CONCLUSIONS

The paucity of existing data highlights the need for further adequately powered studies to evaluate rifalazil, delayed release doxycycline, levofloxacin and other agents for the treatment of uncomplicated CT infections.

PROSPERO REGISTRATION NUMBER

CRD42017073096.

Sexually transmitted infections: Need for extragenital screening

Extragenital infections can occur concurrently with simultaneous urogenital infections. Extragenital sites are believed to serve as hidden reservoirs and play a critical role in their transmission. The etiological relationship of the most widespread Sexually transmitted diseases (STD) pathogen to reproductive tract has long been established, but the distribution to extragenital sites appears to be infrequent and its correlation with the sexual practice still requires to be investigated. Optimal-screening strategies for extragenital infections are largely unknown. However, there is a lack of data on clinical outcomes and optimal treatment regimens for rectal and pharyngeal extragenital infections. Further studies are needed in settings other than reproductive health and STD clinics, especially in primary care clinics and resource-limited settings.

The efficacy of azithromycin and doxycycline treatment for rectal chlamydial infection: a retrospective cohort study in South Australia

BACKGROUND

There are ongoing concerns about treatment failure with azithromycin for the treatment of rectal chlamydia.

AIM

To investigate treatment efficacy of two treatments for rectal chlamydial infection.

METHODS

We performed a retrospective analysis of all patients diagnosed with rectal chlamydial infection between 2009 and 2015 in Adelaide, Australia. Patients were treated with either azithromycin (1 g single dose) or doxycycline (100 mg twice a day for 10 days) and returned for repeat testing 14-180 days after treatment commenced. Log-binomial models were used to estimate the relative risk (RR) of recurrent rectal chlamydia associated with the treatment with azithromycin versus doxycycline.

RESULTS

In men, rectal chlamydia prevalence was 6.7%, and in women, it was 8.1%. Of the 526 patients diagnosed with rectal chlamydial infections, 419 (79.7%), 93 (17.7%) and 14 (2.6%) patients were treated with doxycycline, azithromycin or other medication respectively. Of these patients, 173 (41.3%) of 419 doxycycline-treated patients and 31 (33.3%) of 93 azithromycin-treated patients were retested between 14 and 180 days after treatment commenced (P = 0.16). Among these patients, the repeat rectal chlamydia test was less commonly positive in those treated with doxycycline (5.8%; 95% confidence interval (CI) 0.03-0.10) compared with those treated with azithromycin (19.4%; 95% CI 0.09-0.36) and (P = 0.01). In the multivariate analysis, azithromycin-treated patients had a significantly higher risk of a positive test in the 14 and 180 days after treatment commenced (adjusted relative risk (aRR) 2.96, 95% CI 1.16-7.57).

CONCLUSION

The findings suggest that doxycycline may be more effective than azithromycin in treating rectal chlamydial infections.

Systemic antibody response to Chlamydia Trachomatis infection in patients either infected or reinfected with different Chlamydia serovars

INTRODUCTION

Chlamydia trachomatis is the etiological agent for the most prevalent bacterial sexually transmitted infection in both developed and developing countries. The aim of present study was to characterize the antibody response between two groups of individuals, having either a single C. trachomatis infection and or repeated infections.

MATERIAL AND METHODS

Current study consisted of two groups, one with an initial Chlamydia infection and a second with repeated infections. A titre based estimation of specific serum (IgG and IgA) levels using ELISA were performed, which further validated by western blot. In vitro neutralizing ability of each patient's serum against both homologous and heterologous strains was also determined.

RESULTS

Individuals infected with one of the C. trachomatis serovars D, E or K exhibited a strong systemic antibody response as characterized by ELISA and western blot. These individuals may have developed at least some level of protection as they only represented single infection. By comparison, individuals infected with serovar D, E or F that exhibited low systemic antibody response often presented repeated C. trachomatis infections, suggesting an association with poor immune response. An in vitro neutralizing level of 60-90% was observed in the human sera against homologous serovar D and two heterologous C. trachomatis serovars E and K, compared to <40% against heterologous serovars F.

CONCLUSION

Individuals infected with serovars D and K showed a potential association between circulating antibody response and re-infection risk. While the patients infected with serovars E showed a disconnection between systemic antibody response and re-infection risk.

Efficacy of Genital Chlamidiae Trachomatis Treatment in Women of Reproductive Age

Cervicitis is inflammation of the cervix, and the causes of such inflammation may include infection from certain sexually transmitted diseases (STDs), injury to the cervix from a foreign body inserted into the vagina (for example, birth control devices such as a cervical cap or diaphragm), or cervical cancer, whose course can be subacute or chronic. Our research aimed to test the efficacy of the proposed treatment protocol for chlamydia trachomatis distal genital infections in reproductive women. This single-centre, randomized, quasi-experimental prospective study was conducted among 40 women with diagnosed Chlamydia Trachomatis (CT) cervical infections who were diagnosed and treated at the Clinic of Obstetrics and Gynaecology in the Clinical Center Kragujevac in Serbia from December 2014 to January 2015. Patients were divided into two groups according to the treatment method: the tetracycline group (n=20), with doxiciclyn (Dovicin®) given at a dose of 100 mg twice per day for 10 days and 100 mg per day for the next 10 days, and the macrolides group (n=20), with azithromycin (Hemomycin®) at a dose of 1000 mg per day, divided into four doses or a single dose per day. Treatment with doxycycline proved to be statistically more effective compared to treatment with azithromycin. Our results confirm that the outcome of infections caused by C. trachomatis depends solely on the applied therapy and management, but extensive prospective studies in a female cohort that includes more parameters, such as potential age related, dose-dependent and adherence variability, are necessary to determine and confirm the best choice for treatment of CT cervicitis.

PmpI antibody reduces the inhibitory effect of Vp1 on Chlamydia trachomatis infectivity

Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections. The effect of antibiotic treatment is not satisfactory, and there is currently no vaccine to prevent C. trachomatis infection. Our results showed that Chlamydia virus CPG1 capsid protein Vp1 treatment significantly inhibited C. trachomatis growth in cell culture, and the inclusion numbers of different C. trachomatis serotypes were decreased. In addition, we conducted a preliminary investigation of the possible mechanisms behind the Vp1 inhibition effects and the C. trachomatis molecules targeted by Vp1. Using far-western blot and GST pull-down assay, we found that purified Vp1 can bind to the C. trachomatis outer membrane protein PmpI. PmpI polyclonal antibody treatment markedly reduced the inhibitory effect of Vp1 on C. trachomatis infectivity. On the basis of these experimental results, we infer that PmpI participates in the inhibitory effect of Vp1 and may be a potential receptor of Vp1 in the outer membrane of C. trachomatis. Our research provides clues regarding the molecular mechanisms underlying the interactions between chlamydia virus and chlamydia.

A Population-Based Study to Compare Treatment Outcomes Among Women With Urogenital Chlamydial Infection in Washington State, 1992 to 2015

BACKGROUND

United States guidelines recommend azithromycin or doxycycline for chlamydia (Chlamydia trachomatis [CT]) treatment. These therapies are similarly efficacious for urogenital infections when outcomes are measured 7 to 42 days after treatment, although doxycycline may be superior for rectal infections. Some investigators have suggested that persistent rectal infections may lead to autoinfection of the urogenital tract, potentially resulting in higher rates of recurrent infection in azithromycin-treated women.

METHODS

We used Washington State surveillance data to identify women 14 years or older with urogenital CT (1992-2015) treated with azithromycin or doxycycline. We defined persistent/recurrent CT as a repeat positive CT test result 14 to 180 days after treatment of the initial infection. We used log binomial regression to estimate the adjusted relative risk (aRR) of persistent/recurrent infection associated with treatment with azithromycin versus doxycycline.

RESULTS

From 1992 to 2015, there were 268,596 reported cases of urogenital CT, including 168,301 (63%) who received azithromycin and 66,432 (25%) who received doxycycline. The risk of persistent/recurrent urogenital CT was 6.7% and 4.7% in azithromycin- and doxycycline-treated cases, respectively (P < 0.001). Adjusting for age, race/ethnicity, year, pregnancy status, jurisdiction reporting, reason for examination, and gonorrhea coinfection, azithromycin-treated women were significantly more likely to have persistent/recurrent urogenital CT than doxycycline-treated women (aRR, 1.24; 95% confidence interval [CI], 1.19-1.30). Adjusting the retesting window to 21 to 180 days (aRR, 1.24; 95% CI, 1.19-1.30) and 28 to 180 days (aRR, 1.25; 95% CI, 1.19-1.30) did not alter our primary findings.

CONCLUSIONS

Persistent/recurrent urogenital CT may be more common among women treated with azithromycin than with doxycycline. The reason for this difference is uncertain and is an important area of future investigation.

Clinical diagnostic and therapeutic aspects of 221 consecutive anorectal Chlamydia trachomatis and Neisseria gonorrhoeae sexually transmitted infections among men who have sex with men

OBJECTIVES

Proctitis caused by Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are known as sexually transmitted infections (STI). This study describes their clinical, diagnostic and therapeutic aspects.

METHODS

Between 01/2013-03/2015, all MSM consulting for proctitis at proctology Institute-Saint-Joseph's Hospital, Paris, were included. Demographic, past-medical history, STI status and medical treatment were collected. Detection of CT/NG was performed by Transcription-Mediated Amplification (TMA) and antimicrobial susceptibilities for Ng by agar diffusion method.

RESULTS

On 441 rectal samples collected, 221 (50.1%) were positive: 109 Ct (49.3%), 70 Ng (31.7%), 42 positive for both etiologies (19%). Among Ng infections, no resistance was detected to azithromycin and ceftriaxone. However, 84 strains (43.2%) were resistant to fluoroquinolones. More than one episode was diagnosed for 10 (5.1%) and 12 (6.2%) patients with CT and NG infections respectively. Anal abscesses were found for 27 (13.9%) patients, and 14 (7.2%) of them underwent surgery for anal fistula.

CONCLUSIONS

The prevalence of CT/NG anorectal infections described is high on symptomatic patients, and a significant level of abscess was reported. These results confirm the interest of the association of recommended antibiotics excluding quinolones. Prospective studies would be relevant on complicated forms of anorectal infections.

Retrospective Review of Gonococcal and Chlamydial Cases of Epididymitis at 2 Canadian Sexually Transmitted Infection Clinics, 2004-2014

Fifty-seven cases of gonococcal and chlamydial infections complicated by acute epididymitis seen at 2 Alberta STI clinics from 2004 to 2014 were reviewed. The majority responded to treatment recommended by national guidelines. Three of 6 treatment failures were not treated according to guidelines.

Partner notification and partner treatment for chlamydia: attitude and practice of general practitioners in the Netherlands; a landscape analysis

BACKGROUND

Chlamydia prevalence remains high despite scaling-up control efforts. Transmission is not effectively interrupted without partner notification (PN) and (timely) partner treatment (PT). In the Netherlands, the follow-up of partners is not standardized and may depend on GPs' time and priorities. We investigated current practice and attitude of GPs towards PN and PT to determine the potential for Patient-Initiated Partner Treatment, which is legally not supported yet.

METHODS

Multiple data-sources were combined for a landscape analysis. Quantitative data on (potential) PT were obtained from prescriptions in the national pharmacy register (2004-2014) and electronic patient data from NIVEL-Primary Care Database (PCD) and from STI consultations in a subgroup of sentinel practices therein. Furthermore, we collected information on current practice via two short questionnaires at a national GP conference and obtained insight into GPs' attitudes towards PN/PT in a vignette study among GPs partaking in NIVEL-PCD.

RESULTS

Prescription data showed Azithromycin double dosages in 1-2% of cases in the pharmacy register (37.000 per year); probable chlamydia-specific repeated prescriptions or double dosages of other antibiotics in NIVEL-PCD (115/1078) could not be interpreted as PT for chlamydia with certainty. STI consultation data revealed direct PT in 6/100 cases, via partner prescription or double doses. In the questionnaires the large majority of GPs (>95% of 1411) reported to discuss PN of current and ex-partner(s) with chlamydia patients. Direct PT was indicated as most common method by 4% of 271 GPs overall and by 12% for partners registered in the same practice. Usually, GPs leave further steps to the patients (83%), advising patients to tell partners to get tested (56%) or treated (28%). In the vignette study, 16-20% of 268 GPs indicated willingness to provide direct PT, depending on patient/partner profile, more (24-45%) if patients would have the chance to notify their partner first.

CONCLUSION

GPs in the Netherlands already treat some partners of chlamydia cases directly, especially partners registered in the same practice. Follow-up of partner notification and treatment in general practice needs more attention. GPs may be open to implement PIPT more often, provided there are clear guidelines to arrange this legally and practically.

Bacterial genome sequencing in clinical microbiology: a pathogen-oriented review

In recent years, whole-genome sequencing (WGS) has been perceived as a technology with the potential to revolutionise clinical microbiology. Herein, we reviewed the literature on the use of WGS for the most commonly encountered pathogens in clinical microbiology laboratories: Escherichia coli and other Enterobacteriaceae, Staphylococcus aureus and coagulase-negative staphylococci, streptococci and enterococci, mycobacteria and Chlamydia trachomatis. For each pathogen group, we focused on five different aspects: the genome characteristics, the most common genomic approaches and the clinical uses of WGS for (i) typing and outbreak analysis, (ii) virulence investigation and (iii) in silico antimicrobial susceptibility testing. Of all the clinical usages, the most frequent and straightforward usage was to type bacteria and to trace outbreaks back. A next step toward standardisation was made thanks to the development of several new genome-wide multi-locus sequence typing systems based on WGS data. Although virulence characterisation could help in various particular clinical settings, it was done mainly to describe outbreak strains. An increasing number of studies compared genotypic to phenotypic antibiotic susceptibility testing, with mostly promising results. However, routine implementation will preferentially be done in the workflow of particular pathogens, such as mycobacteria, rather than as a broadly applicable generic tool. Overall, concrete uses of WGS in routine clinical microbiology or infection control laboratories were done, but the next big challenges will be the standardisation and validation of the procedures and bioinformatics pipelines in order to reach clinical standards.

[Non-viral sexually transmitted infections - Epidemiology, clinical manifestations, diagnostics and therapy : Part 2: Chlamydia and mycoplasma]

Chlamydia trachomatis is the most common pathogen of sexually transmitted bacterial infections worldwide. Every year in Germany approximately 300,000 new infections are to be expected. Chlamydia infections occur nearly exclusively in the postpubertal period. The peak age group is 15-25 years. The infection usually runs an asymptomatic course and the diagnosis is made by nucleic acid amplification techniques (NAAT) often after chlamydial screening or if complications occur. For treatment of chlamydial infections oral doxycycline 100 mg twice daily over 7 days is initially used or alternatively oral azithromycin 1.5 g as a single dose is recommended. The sexual partner should also be investigated and treated. Genital Mycoplasma infections are caused by Ureaplasma urealyticum (pathogen of urethritis and vaginitis), Ureaplasma parvum (mostly saprophytic and rarely a cause of urethritis) and Mycoplasma hominis (facultative pathogenic). Mycoplasma genitalium represents a relatively new sexually transmitted Mycoplasma species. Doxycycline is effective in Ureaplasma infections or alternatively clarithromycin and azithromycin. Doxycycline can be ineffective in Mycoplasma hominis infections and an alternative is clindamycin. Non-gonococcal and non-chlamydial urethritis due to Mycoplasma genitalium can now be diagnosed by molecular biological techniques using PCR and should be treated by azithromycin.

Measurement of tissue azithromycin levels in self-collected vaginal swabs post treatment using liquid chromatography and tandem mass spectrometry (LC-MS/MS)

BACKGROUND

Azithromycin is recommended for the treatment of uncomplicated urogenital chlamydia infection although the standard 1gram dose sometimes fails to eradicate the infection (treatment failure). One hypothesis proposed for treatment failure has been insufficient levels of the antibiotic at the site of infection. We developed an assay using liquid chromatography and tandem mass spectrometry (LC-MS/MS) to measure azithromycin concentration in high-vaginal swabs and monitor how concentration changes over time following routine azithromycin treatment.

METHODS

Azithromycin concentrations were measured in two groups of women either within the first 24h of taking a 1g dose (N = 11) or over 9 days (N = 10). Azithromycin concentrations were normalised to an internal standard (leucine enkephalin), and the bulk lipid species phosphatidylcholine [PC(34:1)], using an Agilent 6490 triple quadrupole instrument in positive ionisation mode. The abundances of azithromycin, PC(34:1), and leu-enkephalin were determined by multiple reaction monitoring and absolute levels of azithromycin estimated using standard curves prepared on vaginal specimens.

RESULTS

Vaginal azithromycin concentrations of women were rapidly obtained after 5h post-treatment (mean concentration = 1031mcg/mg of lipid, range = 173-2693mcg/mg). In women followed for 9 days, peak concentrations were highest after day 2 (mean concentration = 2206mcg/mg, range = 721-5791mcg/mg), and remained high for at least 9 days with a mean concentration of 384mcg/mg (range = 139-1024mcg/mg) on day 9.

CONCLUSION

Our study confirmed that a single 1g dose of azithromycin is rapidly absorbed and remains in the vagina at relatively high levels for at least a week, suggesting that poor antibiotic absorption is unlikely to be an explanation for treatment failure.