Anorectal lymphogranuloma venereum among men who have sex with men: a 3-year nationwide survey, France, 2020 to 2022.

BackgroundIn France, lymphogranuloma venereum (LGV) testing switched from universal to selective testing in 2016.AimTo investigate changes in LGV-affected populations, we performed a nationwide survey based on temporarily reinstated universal LGV testing from 2020 to 2022.MethodsEach year, during three consecutive months, laboratories voluntarily sent anorectal Chlamydia trachomatis-positive samples from men and women to the National Reference Centre for bacterial sexually transmitted infections. We collected patients' demographic, clinical and biological data. Genovars L of C. trachomatis were detected using real-time PCR. In LGV-positive samples, the ompA gene was sequenced.ResultsIn 2020, LGV positivity was 12.7% (146/1,147), 15.2% (138/907) in 2021 and 13.3% (151/1,137) in 2022 (p > 0.05). It occurred predominantly in men who have sex with men (MSM), with rare cases among transgender women. The proportion of HIV-negative individuals was higher than that of those living with HIV. Asymptomatic rectal LGV increased from 36.1% (44/122) in 2020 to 52.4% (66/126) in 2022 (p = 0.03). Among users of pre-exposure prophylaxis (PrEP), LGV positivity was 13.8% (49/354) in 2020, 15.6% (38/244) in 2021 and 10.9% (36/331) in 2022, and up to 50% reported no anorectal symptoms. Diversity of the LGV ompA genotypes in the Paris region increased during the survey period. An unexpectedly high number of ompA genotype L1 variant was reported in 2022.ConclusionIn rectal samples from MSM in France, LGV positivity was stable, but the proportion of asymptomatic cases increased in 2022. This underscores the need of universal LGV testing and the importance of continuous surveillance.

Preclinical screen for protection efficacy of chlamydial antigens that are immunogenic in humans.

To search for subunit vaccine candidates, immunogenic chlamydial antigens identified in humans were evaluated for protection against both infection and pathology in a mouse genital tract infection model under three different immunization regimens. The intramuscular immunization regimen was first used to evaluate 106 chlamydial antigens, which revealed that two antigens significantly reduced while 11 increased genital chlamydial burden. The two infection-reducing antigens failed to prevent pathology and 23 additional antigens even exacerbated pathology. Thus, intranasal mucosal immunization was tested next since intranasal inoculation with live Chlamydia muridarum prevented both genital infection and pathology. Two of the 29 chlamydial antigens evaluated were found to prevent genital infection but not pathology and three exacerbate pathology. To further improve protection efficacy, a combinational regimen (intranasal priming + intramuscular boosting + a third intraperitoneal/subcutaneous boost) was tested. This regimen identified four infection-reducing antigens, but only one of them prevented pathology. Unfortunately, this protective antigen was not advanced further due to its amino acid sequence homology with several human molecules. Two pathology-exacerbating antigens were also found. Nevertheless, intranasal mucosal priming with viable C. muridarum in control groups consistently prevented both genital infection and pathology regardless of the subsequent boosters. Thus, screening 140 different chlamydial antigens with 21 repeated multiple times in 17 experiments failed to identify a subunit vaccine candidate but demonstrated the superiority of viable chlamydial organisms in inducing immunity against both genital infection and pathology, laying the foundation for developing a live-attenuated Chlamydia vaccine.

Chlamydia trachomatis infection co-operatively enhances HPV E6-E7 oncogenes mediated tumorigenesis and immunosuppression.

Chlamydia trachomatis and human papilloma virus (HPV) are the two most common sexually transmitted infections among women. HPV infection can increase the risk of cervical cancer and infertility while C. trachomatis induces pelvic inflammatory disease. Here, we elucidate the molecular conundrum of the co-infection of HPV and C. trachomatis infection and their outcome with respect to cervical cancer. HPV infection was mimicked by overexpression of HPV 16 E6-E7 or using human cervical cell lines SiHa and C33a (with and without HPV 16 respectively). HPV transfected co-infection increased cell proliferation and resistance to H202 and TNFα-induced cell death compared to individual infections. These changes are brought by alteration in the cell cycle proteins (CDK2, CDK6 and Bcl2) and thus increasing the stemness of the epithelial cells as observed by increased colony forming units and CD133 expression. The co-infection also induces change in the mRNA levels of cells which are involved in mesenchymal phenotype. C. trachomatis in presence of E6-E7 overexpression caused cervical epithelial neoplasm in mice with increased Ki67 expression and decreased P53 levels. Stem cell marker, CD133 expression also increased in the cervical tissues of both infected and co-infected group of mice. The cells obtained from the cervix were able to grow continuously in ex vivo cultures. All these results indicate the co-existence of the C. trachomatis and HPV 16 might increase the risk of cervical cancer.

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 GeneXpertR 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.

Syndromic surveillance of female sexually transmitted infections in primary care: a descriptive study in Monastir, Tunisia, 2007─2017.

BACKGROUND: Sexually Transmitted Infections (STIs) are a public health problem, especially for reproductive-age women. The aim of this study was to determine the incidence and trend of STIs during 11 years in Tunisia (2007-17). METHODS: We conducted a descriptive study including all women with curable STIs (chlamydia, gonorrhea, syphilis and trichomoniasis) diagnosed with the syndromic approach in all basic health care centers of the Governorate of Monastir (Tunisia) from 2007 to 2017. Syndromes included, Pelvic Pain (PP), Vaginal Discharge (VD) and Genital Ulceration (GU). RESULTS: We analyzed 40,388 episodes of curable STIs with a crude incidence rate and age standardized incidence rate of 1393 (95% Confidence Interval (CI); 1348-1438) / 100,000 Person Year (PY) and 1328 (95%CI; 1284-1372) /100,000 PY respectively. The incidence rate showed a positive trend over 11 years for all age groups and syndromes. VD was the most common syndrome with a crude incidence rate of 1170/100,000 PY. For all syndromes, women aged 20 to 39 were the most affected age group (p < 0.001). CONCLUSION: In conclusion, the incidence rate of STIs episodes among women diagnosed with the syndromic approach was high, consistent with the global evidence. Focusing on reviewing STIs surveillance system in low and middle-income countries could allow the achievement of the ending of STIs epidemics by 2030.

Interferon-γ interferes with host cell metabolism during intracellular Chlamydia trachomatis infection.

Interferon-γ (IFN-γ) is a central mediator of host immune responses including T-cell differentiation and activation of macrophages for the control of bacterial pathogens. Anti-bacterial mechanisms of IFN-γ against the obligate intracellular bacteria Chlamydiatrachomatis in epithelial cells have been intensively investigated in the past, focusing on cellular tryptophan depletion by an IFN-γ induced expression of the indoleamine 2, 3-deoxygenase (IDO). In this study, we could show that IFN-γ treatment caused a significant reduction of the host cell glycolysis that was accompanied by a reduction of glucose transporter-1 (GLUT1) and hypoxia inducible factor-1α (HIF-1α) expression. Furthermore, C. trachomatis induced enhancement of glycolytic and mitochondrial activation were significantly suppressed by IFN-γ treatment. We could further show that glucose starvation, as observed under IFN-γ treatment, was associated with an attenuated antimicrobial efficacy of doxycycline (DOX) against C. trachomatis. In conclusions, anti-chlamydial activity of IFN-γ goes beyond tryptophan depletion including interference with cellular energy metabolism resulting reduced progeny, but also impaired antimicrobial susceptibility of C. trachomatis.

Prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae infections among pregnant women and eye colonization of their neonates at birth time, Shiraz, Southern Iran.

BACKGROUND: Chlamydia trachomatis and Neisseria gonorrhoeae are the two common transmissible pathogens from pregnant women to their neonates. Given the lack of routine screening and treatment of pregnant women in some areas, the possibility of transmission rises. This study seeks to determine the prevalence of C. trachomatis and N. gonorrhoeae in the pregnant women with no clinical symptoms and the vertical transmission rate to their neonates. METHODS: The study was conducted on endocervical and eye swab samples of 239 pregnant women and their neonates. Identification was based on PCR method. RESULTS: The prevalence rates of C.trachomatis in women and neonates were 37/239 (15.5%) and 28/239 (11.7%), and for N. gonorrhoeae 3/239 (1.3%), 1/239 (0.4%), respectively. The vertical transmission rates to the neonates were 28/37(75.6%) for C. trachomatis and 1/3 for N. gonorrhoeae. CONCLUSIONS: In the areas with a high prevalence of chlamydial or gonococcal infections, and in the absence of screening and treatment of the pregnant women, ocular prophylaxis with antibiotics is suggested as a part of routine neonatal care program for the prevention of chlamydial and gonococcal ophthalmia.

Macrolide and fluoroquinolone resistance is uncommon in clinical strains of Chlamydia trachomatis.

We analyzed the 23S rRNA, gyrA and parC genes of Chlamydia trachomatis DNAs from men with urethritis and determined microbiological outcomes of an extended-release azithromycin (azithromycin-SR) regimen (2 g once daily for 1 day) and a sitafloxacin regimen (100 mg twice daily for 7 days) for chlamydial urethritis to clarify the macrolide and fluoroquinolone resistance status of clinical strains of C. trachomatis. We amplified the portions of 2 alleles of the 23S rRNA gene and the gyrA and parC genes from C. trachomatis DNAs in 284 first-voided urine specimens from men with chlamydial urethritis by PCR and sequenced their PCR products. We enrolled 369 men with chlamydial urethritis, comprising 314 and 55 treated with the azithromycin-SR regimen and the sitafloxacin regimen, respectively. Alleles 1 and/or 2 of the 23S rRNA gene were analyzed in 162 specimens. No mutations were found in the sequenced regions, including the central portion of domain V. The gyrA and parC genes were analyzed in 118 and 113 specimens, respectively. No amino acid changes were found within the quinolone resistance-determining region of the gyrA gene and in the sequenced region of the parC gene. The microbiological outcomes of the azithromycin-SR and sitafloxacin regimens were assessed in 176 and 30 men, respectively. The eradication rates were 96.0% (95% CI 93.1%-98.9%) for the azithromycin-SR regimen and 100% for the sitafloxacin regimen. Clinical strains of C. trachomatis with macrolide and/or fluoroquinolone resistance would be uncommon, and azithromycin or fluoroquinolone regimens could be recommended as treatments for chlamydial infections.

Effects of Chlamydia trachomatis infection on sperm chromatin condensation and DNA integrity.

The present study was performed to investigate the relation of Chlamydia trachomatis infection to sperm chromatin/DNA integrity in a population of infertile men (male partner of infertile couples) from Iran. Blood, semen and first-void urine samples were obtained from 250 infertile men. Data were analysed with regard to the results of (i) serological analysis for specific antibodies to C. trachomatis in serum; (ii) the presence of C. trachomatis and DNA in first-void urine; and (iii) in the semen sample of the male partner, in addition to sperm analysis, four different tests (aniline blue, chromomycin A3, acridine orange and TUNEL) were used to detect sperm chromatin and DNA abnormalities. The main conclusions of the results were: (i) no evidence of C. trachomatis infection in semen samples was found; (ii) sperm DNA fragmentation and chromatin studies were not correlated with C. trachomatis diagnosis; (iii) the percentage of DNA fragmentation is positively correlated with the percentage of immotile sperm but negatively with semen volume, normal morphology; and (iv) in sperm chromatin evaluations, only the percentage of chromatin protamination was related to male age.

Cost-benefit analysis of Chlamydia trachomatis screening in pregnant women in a high burden setting in the United States.

BACKGROUND: Chlamydia trachomatis is the most common bacterial sexually transmitted infection (STI) in the United States (U.S.) [1] and remains a major public health problem. We determined the cost- benefit of screening all pregnant women aged 15-24 for Chlamydia trachomatis infection compared with no screening. METHODS: We developed a decision analysis model to estimate costs and health-related effects of screening pregnant women for C. trachomatis in a high burden setting (Brooklyn, NY). Outcome data was from literature for pregnant women in the 2015 US population. A virtual cohort of 6,444,686 pregnant women, followed for 1 year was utilized. Using outcomes data from the literature, we predicted the number of C. trachomatis cases, associated morbidity, and related costs. Two comparison arms were developed: pregnant women who received chlamydia screening, and those who did not. Costs and morbidity of a pregnant woman-infant pair with C. trachomatis were calculated and compared. RESULTS: Cost and benefit of screening relied on the prevalence of C. trachomatis; when rates are above 16.9%, screening was proven to offer net cost savings. At a pre-screening era prevalence of 8%, a screening program has an increased expense of $124.65 million ($19.34/individual), with 328 thousand more cases of chlamydia treated, and significant reduction in morbidity. At a current estimate of prevalence, 6.7%, net expenditure for screening is $249.08 million ($38.65/individual), with 204.63 thousand cases of treated chlamydia and reduced morbidity. CONCLUSIONS: Considering a high prevalence region, prenatal screening for C. trachomatis resulted in increased expenditure, with a significant reduction in morbidity to woman-infant pairs. Screening programs are appropriate if the cost per individual is deemed acceptable to prevent the morbidity associated with C. trachomatis.

Chlamydia trachomatis infection and HPV/Chlamydia trachomatis co-infection among HPV-vaccinated young women at the beginning of their sexual activity.

PURPOSE: This study investigated the prevalence of Chlamydia trachomatis infection, co-infection with Human Papillomavirus (HPV) and associated risk factors in a cohort of sexually active young women enrolled in an ongoing trial on HPV vaccination at the European Institute of Oncology (IEO, Milan, Italy). METHODS: Cervical samples were collected from 591 girls (median age 18.8 years) at the beginning of their sexual activity. At the time of sample collection, 354 women had not yet been vaccinated, and 237 women had been vaccinated for at least 12 months. All samples were analyzed through a molecular assay for the detection of C. trachomatis infection. Demographic, behavioral risk factors and high-risk HPV (HR-HPV) status were investigated. RESULTS: The prevalence of C. trachomatis infection was 4.9 % and HPV/C. trachomatis co-infection rate was 1.5 %. The exact analysis has not underlined statistical significance for the variables considered, except for the infection with HR-HPV (p < 0.001). The prevalence of C. trachomatis infection among women who had not been immunized and those already vaccinated was similar (5.6 vs 3.8 %). However, the rate of HPV/C. trachomatis co-infection was twice as high in unvaccinated women (2 %) compared to vaccinated women (0.8 %). CONCLUSIONS: Over 16 % of young women had at least one of the two STIs investigated. The risk of C. trachomatis infection was higher in HR-HPV infected compared to HR-HPV uninfected young women. The rate of co-infection was halved in HPV-vaccinated compared to unvaccinated women. This study underlines that HPV vaccination can confer benefits also in terms of co-infections prevention, leading to a decreased risk of developing cervical malignancies.

Molecular epidemiology and genotyping of Chlamydia trachomatis infection in a cohort of young asymptomatic sexually active women (18-25 years) in Milan, Italy.

INTRODUCTION: Chlamydia trachomatis (Ct) is the most common bacterial cause of sexually transmitted infections (STI) and is associated with severe long-term sequelae in female populations. In Italy Ct infections are not submitted to a screening programme, and its epidemiological profile is understudied. Even scarcer information is available about the genetic diversity on ompA gene, whose sequence defines 18 different genovars. This study aims at evaluating the prevalence of Ct infection in young sexually active asymptomatic women aged 18-25, and characterizing the molecular epidemiology of the different circulating genovars in this population. METHODS: Cervical samples collected from 909 sexually-activeyoung women (mean age 21.5 years) were analyzed through molecular assay for the detection of Ct infection. Phylogenetic analysis on the ompA gene was performed on Ct positive samples to identify the circulating genovars. RESULTS: The overall prevalence of Ct-infection was 4.4% (95%CI: 3.2-5.9%): 5.3% among women aged 18-21 years and 3.5% among those aged 22-25 years. Phylogenetic analysis has identified 5 different genovars: D, E, F, G, and H. The most common genovar was the E (46%), followed by genovar F and G (18.9% each), D (13.5%), and H (2.7%). CONCLUSIONS: This study underlines the high prevalence of asymptomatic Ct-infections among young women. Overall, about half of the asymptomatic infections is sustained by genovar E. The introduction in Italy of a systematic screening program should be considered to allow a better understanding of Ct spreading and providing women with an opportunity for early treatment to protect their sexual and reproductive health.

Effects of vaginal lactobacilli in Chlamydia trachomatis infection.

Increasing evidence indicates that abnormal vaginal flora lacking lactobacilli facilitates the acquisition of several sexually transmitted diseases including Chlamydia trachomatis. C. trachomatis, the most common bacterial agent of genital infections worldwide, can progress from the lower to upper reproductive tract and induce severe sequelae. The ability of C. trachomatis to develop into a persistent form has been suggested as key pathogenetic mechanism underlying chronic infections and sequelae. The aim of our study was to investigate the C. trachomatis interaction with vaginal microbiota analyzing the effects of Lactobacillus strains (L. brevis and L. salivarius) on the different phases of C. trachomatis developmental cycle. In addition, the effect of lactobacilli on persistent chlamydial forms induced by HSV-2 coinfection has also been evaluated. Our results demonstrated significant inhibition of C. trachomatis multiplication by vaginal lactobacilli. L. brevis was significantly more effective than L. salivarius (p<0.05) on all the steps of chlamydial infection cycle suggesting that the ability of lactobacilli to protect from infection is strain-dependent. Lactobacilli had an adverse effect on elementary chlamydial bodies (p<0.05), on chlamydial adsorption to epithelial cells (p<0.001) and on intracellular phases of chlamydial replication (p<0.0001). Our study also demonstrated a protective effect of lactobacilli toward persistent C. trachomatis forms induced by HSV-2 coinfection. A significant increase in the production of C. trachomatis infectious progeny was observed in C. trachomatis/HSV-2 coinfection in the presence of L. brevis (p=0.01) despite a significant inhibition of C. trachomatis multiplication (p=0.028). Our data suggest that a healthy vaginal microbiota can reduce the risk of acquiring C. trachomatis infection and counteract the development of persistent chlamydial forms.

Seminal plasma inhibits Chlamydia trachomatis infection in vitro, and may have consequences on mucosal immunity.

Seminal plasma (SP) is the main vector of C. trachomatis (CT) during heterosexual transmission from male to female. It has immunomodulatory properties and impacts the susceptibility to HIV-1 infection, but its role has not been explored during CT infection. In the female reproductive tract (FRT), CT infection induces cytokine production and neutrophil recruitment. The role of neutrophils during CT infection is partially described, they could be at the origin of the pathology observed during CT infection. During this study, we developed an experimental in vitro model to characterize the impact of CT infection and SP on endocervical epithelial cell immune response in the FRT. We also studied the impact of the epithelial cell response on neutrophil phenotype and functions. We showed that the production by epithelial cells of pro-inflammatory cytokines increased during CT infection. Moreover, the pool of SP as well as individuals SP inhibited CT infection in a dose-dependent manner. The pool of SP inhibited cytokine production in a dose-dependent manner. The pool of SP altered gene expression profiles of infected cells. The culture supernatants of cells infected or not with CT, in presence or not of the pool of SP, had an impact on neutrophil phenotype and functions: they affected markers of neutrophil maturation, activation and adhesion capacity, as well as the survival, ROS production and phagocytosis ability. This study proposes a novel approach to study the impact of the environment on the phenotype and functions of neutrophils in the FRT. It highlights the impact of the factors of the FRT environment, in particular SP and CT infection, on the mucosal inflammation and the need to take into account the SP component while studying sexually transmitted infections during heterosexual transmission from male to female.

Challenges in Chlamydial Serology: Insights from a Belgian and a Dutch Population Cohort.

Serology routinely serves as a diagnostic tool to confirm Chlamydia infections in humans. Particularly in delayed settings, such as post-outbreak scenarios where the acute phase of infection has subsided, serology is invaluable. Multiple studies, nonetheless, indicate deficiencies in specificity and sensitivity of current chlamydial antibody detection assays. Incorporation of multiple antigens per target is known to improve the accuracy of chlamydial serological assays. We, therefore, used the recomLine test (Mikrogen diagnostics) on serological samples of two cohorts, as it is the only commercially available test allowing detection of antibodies against three human pathogenic Chlamydia species (C. trachomatis, C. pneumoniae and C. psittaci) using multiple antigens per target. The first cohort (n = 156; samples collected between 2008 and 2022 during a C. trachomatis screening initiative) comprised women from the Netherlands (NL) with past exposure to C. trachomatis, while the second cohort (n = 44; samples collected in 2018 in a health examination survey) consisted of Belgian citizens (BE) with occupational or recreational exposure to chickens, representing a risk population for C. psittaci. The test indicated a statistically equivalent C. pneumoniae seroprevalence in both cohorts (39.10% in NL and 34.09% in BE; p = 0.337). As expected C. trachomatis seroprevalence was significantly higher (p < 0.001) in the Dutch cohort (48.72%), as compared to the Belgian cohort (4.55%). Lastly, C. psittaci seroprevalence did not significantly differ between the two groups (2.27% in BE and 1.92% in NL; p = 0.633), even though a higher prevalence was expected for the Belgian cohort. This prompts us to question whether the Belgian cohort truly constituted a C. psittaci risk population or whether the recomLine test is susceptible to cross-reaction of species-specific antibodies, thereby increasing C. psittaci prevalence in the Dutch cohort. We advocate for the development of affordable, highly sensitive antibody detection assays that can effectively distinguish between chlamydial species, addressing the increasing demand for enhanced serological testing methodologies.

IFNγ insufficiency during mouse intra-vaginal Chlamydia trachomatis infection exacerbates alternative activation in macrophages with compromised CD40 functions.

Chlamydia trachomatis (C.tr), an obligate intracellular pathogen, causes asymptomatic genital infections in women and is a leading cause of preventable blindness. We have developed in vivo mouse models of acute and chronic C. trachomatis genital infection to explore the significance of macrophage-directed response in mediating immune activation/suppression. Our findings reveal that during chronic and repeated C. trachomatis infections, Th1 response is abated while Treg response is enhanced. Additionally, an increase in exhaustion (PD1, CTLA4) and anergic (Klrg3, Tim3) T cell markers is observed during chronic infection. We have also observed that M2 macrophages with low CD40 expression promote Th2 and Treg differentiation leading to sustained C. trachomatis genital infection. Macrophages infected with C. trachomatis or treated with supernatant of infected epithelial cells drive them to an M2 phenotype. C. trachomatis infection prevents the increase in CD40 expression as observed in western blots and flow cytometric analysis. Insufficient IFNγ, as observed during chronic infection, leads to incomplete clearance of bacteria and poor immune activation. C. trachomatis decapacitates IFNγ responsiveness in macrophages via hampering IFNγRI and IFNγRII expression which can be correlated with poor expression of MHC-II, CD40, iNOS and NO release even following IFNγ supplementation. M2 macrophages during C. trachomatis infection express low CD40 rendering immunosuppressive, Th2 and Treg differentiation which could not be reverted even by IFNγ supplementation. The alternative macrophages also harbour high bacterial load and are poor responders to IFNγ, thus promoting immunosuppression. In summary, C. trachomatis modulates the innate immune cells, attenuating the anti-chlamydial functions of T cells in a manner that involves decreased CD40 expression on macrophages.

Metabolic model guided CRISPRi identifies a central role for phosphoglycerate mutase in Chlamydia trachomatis persistence.

Upon nutrient starvation, Chlamydia trachomatis serovar L2 (CTL) shifts from its normal growth to a non-replicating form, termed persistence. It is unclear if persistence reflects an adaptive response or a lack thereof. To understand this, transcriptomics data were collected for CTL grown under nutrient-replete and nutrient-starved conditions. Applying K-means clustering on transcriptomics data revealed a global transcriptomic rewiring of CTL under stress conditions in the absence of any canonical global stress regulator. This is consistent with previous data that suggested that CTL's stress response is due to a lack of an adaptive response mechanism. To investigate the impact of this on CTL metabolism, we reconstructed a genome-scale metabolic model of CTL (iCTL278) and contextualized it with the collected transcriptomics data. Using the metabolic bottleneck analysis on contextualized iCTL278, we observed that phosphoglycerate mutase (pgm) regulates the entry of CTL to the persistence state. Our data indicate that pgm has the highest thermodynamics driving force and lowest enzymatic cost. Furthermore, CRISPRi-driven knockdown of pgm in the presence or absence of tryptophan revealed the importance of this gene in modulating persistence. Hence, this work, for the first time, introduces thermodynamics and enzyme cost as tools to gain a deeper understanding on CTL persistence. IMPORTANCE: This study uses a metabolic model to investigate factors that contribute to the persistence of Chlamydia trachomatis serovar L2 (CTL) under tryptophan and iron starvation conditions. As CTL lacks many canonical transcriptional regulators, the model was used to assess two prevailing hypotheses on persistence-that the chlamydial response to nutrient starvation represents a passive response due to the lack of regulators or that it is an active response by the bacterium. K-means clustering of stress-induced transcriptomics data revealed striking evidence in favor of the lack of adaptive (i.e., a passive) response. To find the metabolic signature of this, metabolic modeling pin-pointed pgm as a potential regulator of persistence. Thermodynamic driving force, enzyme cost, and CRISPRi knockdown of pgm supported this finding. Overall, this work introduces thermodynamic driving force and enzyme cost as a tool to understand chlamydial persistence, demonstrating how systems biology-guided CRISPRi can unravel complex bacterial phenomena.

Chlamydia-driven ISG15 expression dampens the immune response of epithelial cells independently of ISGylation.

Excessive inflammation upon Chlamydia trachomatis infection can cause severe damages in the female genital tract. This obligate intracellular bacterium develops mainly in epithelial cells, whose innate response contributes to the overall inflammatory response to infection. The ubiquitin-like protein interferon-stimulated gene 15 (ISG15) stimulates interferon γ (IFNγ) production and is required for bacterial clearance in several infectious contexts. Here, we describe and investigate the consequences of the increase in ISG15 expression by epithelial cells infected with C. trachomatis. Infection of HeLa cells and primary ecto-cervical epithelial cells resulted in a transcriptional upregulation of ISG15 expression. This did not involve the canonical type I interferon (IFN-I) signaling pathway and depended instead on the activation of the STING/TBK1/IRF3 pathway. The absence or reduction of ISG15 synthesis led to increased production of several cytokines and chemokines, including interleukin (IL) 6 and IL8. This implicates that ISG15 normally dampens the immune response induced by C. trachomatis infection in epithelial cells. ISG15 exerted its control from an intracellular location, but without involving ISGylation. Finally, higher levels of inflammation and delayed bacterial clearance were observed in the genital tracts of ISG15-KO mice infected by C. trachomatis compared with wild-type animals; however, IFNγ production was unchanged. Altogether, our data show that ISG15 expression acts as a brake on the immune response to C. trachomatis infection in epithelial cells and limits bacterial burden and inflammation in mice.IMPORTANCEInfection of epithelial cells by Chlamydia trachomatis elicits an innate immune response by these cells. The signaling pathways involved, and their outcomes, are still very poorly understood. In this paper, we described how Chlamydia infection triggered the expression of ISG15, a small molecule normally associated to type I interferon (IFN-I) signaling and control of INF-γ production. ISG15 synthesis by epithelial cells attenuated their immune response to Chlamydia infection. In mice, we observed that ISG15 displayed a marginal role in modulating the production of IFN-γ, a key component of the host immune response to infection, but facilitated bacterial clearance. Overall, our study strengthens the importance of ISG15 not only in the resolution of viral but also of bacterial infection and document its role of "immune brake" in the context of Chlamydia infection.

Heterologous Display of Chlamydia trachomatis PmpD Passenger at the Surface of Salmonella OMVs.

Chlamydia trachomatis is the bacterial pathogen that causes most cases of sexually transmitted diseases annually. To combat the global spread of asymptomatic infection, development of effective (mucosal) vaccines that offer both systemic and local immune responses is considered a high priority. In this study, we explored the expression of C. trachomatis full-length (FL) PmpD, as well as truncated PmpD passenger constructs fused to a "display" autotransporter (AT) hemoglobin protease (HbpD) and studied their inclusion into outer membrane vesicles (OMVs) of Escherichia coli and Salmonella Typhimurium. OMVs are considered safe vaccine vectors well-suited for mucosal delivery. By using E. coli AT HbpD-fusions of chimeric constructs we improved surface display and successfully generated Salmonella OMVs decorated with a secreted and immunogenic PmpD passenger fragment (aa68-629) to 13% of the total protein content. Next, we investigated whether a similar chimeric surface display strategy could be applied to other AT antigens, i.e., secreted fragments of Prn (aa35-350) of Bordetella pertussis and VacA (aa65-377) of Helicobacter pylori. The data provided information on the complexity of heterologous expression of AT antigens at the OMV surface and suggested that optimal expression strategies should be developed on an antigen-to-antigen basis.

High Prevalence of Sexually Transmitted and Reproductive Tract Infections (STI/RTIs) among Patients Attending STI/Outpatient Department Clinics in Tanzania.

We determined the prevalence and reported risk factors associated with sexually transmitted and reproductive tract infections (STI/RTIs) among patients who presented with genital symptoms in STI/outpatient department (OPD) clinics in two regional referral hospitals and six health centres in six regions in Tanzania. Methods: The patients were consecutively recruited, and the data collection was conducted in eight health care facilities from 2014 to 2016. Genital swabs were collected for the detection of the aetiological pathogens of STI/RTIs. Results: A total of 1243 participants were recruited in the study; the majority (1073, 86%) were women. The overall median age was 27.8. The prevalence of Neisseria gonorrhoeae was 25.7% (319/1243), with proportions of 50.9 and 21.5% for men and women, respectively, of Chlamydia trachomatis 12.9% (160/1241) and Mycoplasma genitalium 4.7% (53/1134). Unmarried men were more often likely to be infected with gonococcal infections as compared to their women counterparts (57.9 vs. 24.1%) p < 0.001. The majority presented with genital discharge syndrome (GDS) 93.6% (1163/1243), genital ulcer disease (GUD) 13.0% (162/1243) and GDS + GUD 9.6% (119/1243). GDS was more common in the health centres, 96.1% (1195/1243), vs. the regional referral hospitals, 92.2% (1146/1243) (p = 0.01), but those reported to the regional referral hospitals were more likely to be infected with N. gonorrhoeae (OR = 2.5) and C. trachomatis (OR = 2.1) than those from the health centres (p < 0.001). The prevalence of bacterial vaginosis (BV) and vaginal candidiasis (VC) was 24.1 and 10.4%, respectively. Interestingly, unmarried and BV-positive women were less likely to be infected with VC (p = 0.03), though VC was strongly inversely associated with an N. gonorrhoeae infection (p < 0.001). High proportions of N. gonorrhoeae (51.1%) and C. trachomatis (23.3%) were found in the Dodoma and Dar es Salaam regions, respectively. M. genitalium (7.6%) was found to be the highest in Mwanza. Conclusion: We reported a high prevalence of STI/RTIs. The findings suggest that these infections are common and prevalent in STI/OPD clinics in six regions of Tanzania. We recommend surveillance to be conducted regularly to elucidate the true burden of emerging and classical STI/RTIs by employing modern and advanced laboratory techniques for the detection and monitoring of STI/RTIs in low- and high-risk populations, including the community settings.