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BACKGROUND: RNA sequencing (RNA-Seq) offers profound insights into the complex transcriptomes of diverse biological systems. However, standard differential expression analysis pipelines based on DESeq2 and edgeR encounter challenges when applied to the immediate early transcriptomes of Chlamydia spp., obligate intracellular bacteria. These challenges arise from their reliance on assumptions that do not hold in scenarios characterized by extensive transcriptomic activation and limited repression. RESULTS: Standard analyses using unique chlamydial RNA-Seq reads alone identify nearly 300 upregulated and about 300 downregulated genes, significantly deviating from actual RNA-Seq read trends. By incorporating both chlamydial and host reads or adjusting for total sequencing depth, the revised normalization methods each detected over 700 upregulated genes and 30 or fewer downregulated genes, closely aligned with observed RNA-Seq data. Further validation through qRT-PCR analysis confirmed the effectiveness of these adjusted approaches in capturing the true extent of transcriptomic activation during the immediate early phase of chlamydial infection. CONCLUSIONS: This study highlights the limitations of standard RNA-Seq analysis tools in scenarios with extensive transcriptomic activation, such as in Chlamydia spp. during early infection. Our revised normalization methods, incorporating host reads or total sequencing depth, provide a more accurate representation of gene expression dynamics. These approaches may inform similar adjustments in other systems with unbalanced gene expression dynamics, enhancing the accuracy of transcriptomic analysis.

BACKGROUND: The obligate intracellular bacterial family Chlamydiaceae comprises a number of different species that cause disease in various vertebrate hosts including humans. Chlamydia suis, primarily found in the gastrointestinal tract of pigs, is the only species of the Chlamydiaceae family to have naturally gained tetracycline resistance (TetR), through a genomic island (Tet-island), integrated into the middle of chromosomal invasin-like gene inv. Previous studies have hypothesised that the uptake of the Tet-island from a host outside the Chlamydiaceae family was a unique event, followed by spread among C. suis through homologous recombination. In vitro recombination studies have shown that Tet-island exchange between C. suis strains is possible. Our aim in this study was to gain a deeper understanding of the interclade recombination of the Tet-island, among currently circulating C. suis field strains compared to in vitro-generated recombinants, using published whole genome sequences of C. suis field strains (n = 35) and in vitro-generated recombinants (n = 63). RESULTS: We found that the phylogeny of inv better reflected the phylogeny of the Tet-island than that of the whole genome, supporting recombination rather than site-specific insertion as the means of transfer. There were considerable differences between the distribution of recombinations within in vitro-generated strains compared to that within the field strains. These differences are likely because in vitro-generated recombinants were selected for a tetracycline and rifamycin/rifampicin resistant background, leading to the largest peak of recombination across the Tet-island. Finally, we found that interclade recombinations across the Tet-island were more variable in length downstream of the Tet-island than upstream. CONCLUSIONS: Our study supports the hypothesis that the occurrence of TetR strains in both clades of C. suis came about through interclade recombination after a single ancestral horizontal gene transfer event.

Introduction: Bacterial urinary tract infections (UTI) and some sexually transmitted infections (STI) can have overlapping signs and symptoms or nonspecific findings, such as pyuria on urinalysis. Furthermore, results from the urine culture and the nucleic acid amplification test for an STI may not be available during the clinical encounter. We sought to determine whether gonorrhea, chlamydia, and trichomoniasis are associated with bacteriuria, information that might aid in the differentiation of STIs and UTIs.Methods: We used multinomial logistic regression to analyze 9,650 encounters of female patients whowere aged ≥18 years and who underwent testing for STIs. The ED encounters took place from April 18, 2014–March 7, 2017. We used a multivariable regression analysis to account for patient demographics, urinalysis findings, vaginal wet-mount results, and positive or negative (or no) findings from the urine culture and testing for Neisseria gonorrhoeae, Chlamydia trachomatis, or Trichomonas vaginalis.Results: In multivariable analysis, infection with T vaginalis, N gonorrhoeae, or C trachomatis was not associated with having a urine culture yielding 10,000 or more colony-forming units per mililiter (CFU/mL) of bacteria compared with a urine culture yielding less than 10,000 CFU/mL or no urine culture obtained. The diagnosis of a UTI in the ED was not associated with having a urine culture yielding 10,000 or more CFU/mL compared with a urine culture yielding less than 10,000 CFU/mL.Conclusion: After adjusting for covariates, no association was observed between urine culture results and testing positive for trichomoniasis, gonorrhea, or chlamydia. Our results suggest that having a concurrent STI and bacterial UTI is unlikely.

Introduction: The incidence of sexually transmitted infections (STI) increased in the United States between 2017–2021. There is limited data describing STI co-testing practices and the prevalence of STI co-infections in emergency departments (ED). In this study, we aimed to describe the prevalence of co-testing and co-infection of HIV, hepatitis C virus (HCV), syphilis, gonorrhea, and chlamydia, in a large, academic ED.Methods: This was a single-center, retrospective cross-sectional study of ED patients tested for HIV, HCV, syphilis, gonorrhea or chlamydia between November 27, 2018–May 26, 2019. In 2018, the study institution implemented an ED-based infectious diseases screening program in which any patient being tested for gonorrhea/chlamydia was eligible for opt-out syphilis screening, and any patient 18–64 years who was having blood drawn for any clinical purpose was eligible for opt-out HIV and HCV screening. Weanalyzed data from all ED patients ≥13 years who had undergone STI testing. The outcomes of interest included prevalence of STI testing/co-testing and the prevalence of STI infection/co-infection. We describe data with simple descriptive statistics.Results: During the study period there were 30,767 ED encounters for patients ≥13 years (mean age: 43 ± 14 years, 52% female), and 7,866 (26%) were tested for at least one of HIV, HCV, syphilis, gonorrhea, or chlamydia. We observed the following testing frequencies (and prevalence of infection): HCV, 7,539 (5.0%); HIV, 7,359 (0.9%); gonorrhea, 574 (6.1%); chlamydia, 574 (9.8%); and syphilis, 420 (10.5%). Infectious etiologies with universal testing protocols (HIV and HCV) made up the majority of STI testing. In patients with syphilis, co-infection with chlamydia (21%, 9/44) and HIV (9%, 4/44) was high. In patients with gonorrhea, co-infection with chlamydia (23%, 8/35) and syphilis (9%, 3/35) was high, and in patients with chlamydia, co-infection with syphilis (16%, 9/56) and gonorrhea (14%, 8/56) was high. Patients with HCV had low co-infection proportions (

BACKGROUND: Neisseria gonorrheae and Chlamydia trachomatis are associated with mucosal inflammation and human immunodeficiency virus 1 (HIV-1) transmission. We assessed levels of inflammatory cytokines in men who have sex with men (MSM) with and without rectal gonorrhea and/or chlamydia in Lima, Peru. METHODS: We screened 605 MSM reporting condomless receptive anal intercourse for rectal N. gonorrheae/C. trachomatis using nucleic acid testing. We identified 101 cases of gonorrhea and/or chlamydia and randomly selected 50 N. gonorrheae/C. trachomatis positive cases and matched 52 negative controls. We measured levels of IL-1β, IL-6, IL-8, and TNF-α in rectal secretions. Tests for HIV-1, rectal N. gonorrheae/C. trachomatis, and mucosal cytokines were repeated after 3 and 6 months. Cytokine levels in cases and uninfected controls were compared using Wilcoxon rank-sum tests and linear regression. RESULTS: MSM with gonorrhea/chlamydia had elevated levels of all cytokines in rectal mucosa compared with matched controls (all P values .05). DISCUSSION: Rectal gonorrhea/chlamydia infection is associated with transient mucosal inflammation and cytokine recruitment. Our data provide proof of concept for rectal sexually transmitted infection screening as an HIV prevention strategy for MSM. Clinical Trials Registration. NCT03010020.

The obligate intracellular bacterium Chlamydia has a unique developmental cycle that alternates between two contrasting cell types. With a hardy envelope and highly condensed genome, the small elementary body (EB) maintains limited metabolic activities yet survives in extracellular environments and is infectious. After entering host cells, EBs differentiate into larger and proliferating reticulate bodies (RBs). Progeny EBs are derived from RBs in late developmental stages and eventually exit host cells. How expression of the chlamydial genome consisting of nearly 1,000 genes governs the chlamydial developmental cycle is unclear. A previous microarray study identified only 29 Chlamydia trachomatis immediate early genes, defined as genes with increased expression during the first hour postinoculation in cultured cells. In this study, we performed more sensitive RNA sequencing (RNA-Seq) analysis for C. trachomatis cultures with high multiplicities of infection. Remarkably, we observed well over 700 C. trachomatis genes that underwent 2- to 900-fold activation within 1 hour postinoculation. Quantitative reverse transcription real-time PCR analysis was further used to validate the activated expression of a large subset of the genes identified by RNA-Seq. Importantly, our results demonstrate that the immediate early transcriptome is over 20 times more extensive than previously realized. Gene ontology analysis indicates that the activated expression spans all functional categories. We conclude that over 70% of C. trachomatis genes are activated in EBs almost immediately upon entry into host cells, thus implicating their importance in initiating rapid differentiation into RBs and establishing an intracellular niche conducive with chlamydial development and growth.

Hallmarks of the developmental cycle of the obligate intracellular pathogenic bacterium Chlamydia are the primary differentiation of the infectious elementary body (EB) into the proliferative reticulate body (RB) and the secondary differentiation of RBs back into EBs. The mechanisms regulating these transitions remain unclear. In this report, we developed an effective novel strategy termed dependence on plasmid-mediated expression (DOPE) that allows for the knockdown of essential genes in Chlamydia. We demonstrate that GrgA, a Chlamydia-specific transcription factor, is essential for the secondary differentiation and optimal growth of RBs. We also show that GrgA, a chromosome-encoded regulatory protein, controls the maintenance of the chlamydial virulence plasmid. Transcriptomic analysis further indicates that GrgA functions as a critical regulator of all three sigma factors that recognize different promoter sets at developmental stages. The DOPE strategy outlined here should provide a valuable tool for future studies examining chlamydial growth, development, and pathogenicity.

AbstractObjectiveStudy designMethodsResultsConclusionOur objective was to assess trends in three sexually transmitted infections (STIs) – gonorrhoea, chlamydia and syphilis – in Spain, by age group and sex from 2016 to 2022.Retrospective observational studyData from epidemiological surveillance system were used to calculate the incidence rate for each STIs by age group and sex. Poisson regression was employed to examine the trends for 2016 to 2022.For gonorrhoea, higher incidence rates were observed among men than women for all period. The incidence rate ratio (IRR) varied between 1.14 (95% CI 1.12–1.16) for the 15–19 age group to 1.24 (1.23–1.25) for the 35–44 age group among men, and between 1.14 (1.09–1.19) for 55 years or more to 1.27 (1.24–1.29) for the 15–19 age group among women. For chlamydia, women showed higher incidence rate for all age groups than men during the period. Individuals aged 55 years and over showed the highest increase, IRR = 1.30 (1.27–1.34) for men, while it was the lowest for women, IRR = 1.22 (1.16–1.27). The incidence rates for syphilis were lower than for the other STIs. IRR values varied between 1.04 (1.02–1.06) in the 20–24 age group and 1.15 (1.14–1.16) in the 35–44 age group for males; and between 1.13 (1.06–1.16) for the 25–34 age group and 1.18 (1.13–1.25) for the 25–34 age group for females.STIs are more frequent in people aged 25–34 and are increasing in all age groups. However, the rise is most pronounced among older men and among younger women. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Methods Results Conclusions Implications for the Profession Impact Reporting Method Patient Contribution To increase Chlamydia trachomatis screening in adolescents 15–19 years of age from 7.8% to 15% following a 6‐week implementation of universal chlamydia screening at three paediatric primary care (PPC) sites.Pre‐implementation (1 January 2022–19 October 2022) and post‐implementation (20 October 2022–1 June 2023) screening rates were tracked through run charts and compared via Chi‐square testing. Universal opt‐out chlamydia screening with universal urine collection for 15‐ to 19‐year‐old was implemented at well visits, along with patient and staff education, and sexually transmitted infection treatment protocols.Chlamydia trachomatis screening increased from 7.8% to 34.1% with implementation of universal opt‐out chlamydia screening. Proportions of patients screened increased significantly among White individuals, males and privately insured individuals.A universal C. trachomatis screening project can be feasibly implemented in pediatric primary care and successfully increase adolescent chlamydia screening rates.Implementing a universal opt‐out C. trachomatis screening project is feasible in PPC and can help achieve the public health goal of chlamydia identification and treatment.These findings will be impactful for both paediatric primary care and adolescent patients. The universal, opt‐out C. trachomatis screening approach facilitated screening increases, improved equity in screening and led to increased case detection and treatment which has vast significance for those patients.This manuscript is submitted using the SQUIRE 2.0 guidelines for quality improvement reporting.Patient contribution included de‐identified data collection of chlamydia screening rates of eligible adolescents 15–19 years old who attended routine well visits at the three PPC locations. The data were reviewed on a dashboard, then stratified by race, ethnicity, payor and sex assigned at birth. [ABSTRACT FROM AUTHOR]

Chlamydia abortus is a reported cause of infertility and endometritis in sheep, cattle, and pigs; however, the association between uterine disease and C. abortus is poorly understood in horses. Recently, a high prevalence of C. abortus in equine aborted chorioallantoises was reported in horses in western Canada. Based on this high prevalence, investigation into the effects of C. abortus on infertility and endometritis in western Canadian mares is prudent. We examined 98 formalin-fixed, paraffin-embedded endometrial biopsies from western Canada submitted between 2014 and 2022 using a Chlamydia -specific 16S rRNA PCR test; 40 samples tested positive for Chlamydia on PCR, and 28 were sequenced as C. abortus. The C. abortus –positive cases were primarily associated with a history of failure to conceive, early embryonic loss, or abortion. Our findings suggest that C. abortus may be a cause of conception failure and abortion in horses in western Canada. [ABSTRACT FROM AUTHOR]

Background Chlamydia trachomatis is the causative agent of the most prevalent bacterial sexually transmitted infections globally. Whole genome sequencing is essential for molecular Chlamydia surveillance; however, its application is hampered by the pathogen's low abundance in clinical specimens and the expensive labor-intensive nature of existing enrichment methodologies for Chlamydia. Methods We developed a targeted whole genome amplification tool termed SWITCH by integrating phi29 DNA polymerase-mediated amplification with meticulously designed primer sets to enrich the C trachomatis genome, followed by whole genome sequencing. This method underwent evaluation through testing synthetic and clinical specimens. Results SWITCH demonstrated robust ability to achieve up to 98.3% genomic coverage of C trachomatis from as few as 26.4 genomic copies present in synthetic specimens, and it exhibited excellent performance across diverse C trachomatis serovars. Utilizing SWITCH, we directly generated 21 Chlamydia genomes from 26 clinical samples, enabling us to gain insights into the genetic relationships and phylogeny of current Chlamydia strains circulating in the country. Remarkably, this study marked the first instance of generating Chinese Chlamydia genomes directly from clinical samples. Conclusions SWITCH represents a practical cost-efficient approach to enrich the Chlamydia genome directly from clinical specimens, offering an efficient avenue for molecular surveillance of Chlamydia. [ABSTRACT FROM AUTHOR]

ABSTRACT We consider the problem of combining multiple biomarkers to improve the diagnostic accuracy of detecting a disease when only group‐tested data on the disease status are available. There are several challenges in addressing this problem, including unavailable individual disease statuses, differential misclassification depending on group size and number of diseased individuals in the group, and extensive computation due to a large number of possible combinations of multiple biomarkers. To tackle these issues, we propose a pairwise model fitting approach to estimating the distribution of the optimal linear combination of biomarkers and its diagnostic accuracy under the assumption of a multivariate normal distribution. The approach is evaluated in simulation studies and applied to data on chlamydia detection and COVID‐19 diagnosis. [ABSTRACT FROM AUTHOR]

Purpose: Conjunctivitis is one of the most common ocular conditions in clinical practice. Human adenoviruses have been the common causative agents known to cause epidemic kerato-conjunctivitis (EKC) in India from 1996 to 2019 with a positivity range of 13.8%–65.2%. The current study was initiated to throw light on the distribution of keratoconjunctivitis causing agents across India covering a span of 3 years. Methods: A total of 709 swabs were collected from patients in viral transport medium (VTM), and real-time PCR was done to identify agents including Adenovirus (HAdV), Enterovirus, HSV, and Chlamydia. Results: 47.8% of the samples were positive for HAdV followed by HSV (3.4%), Enterovirus (2.7%), and Chlamydia (0.6%). Overall, 386 people (54.4%) tested positive for one of these infections, with Chandigarh (88.4%) and Port Blair (71.7%) showing higher positivity rate. Pre-auricular lymphadenopathy and follicles were significantly associated with increased risk of conjunctivitis. Conclusion: Epidemiology of keratoconjunctivitis in the current study revealed HAdV to be predominant causative agent. Knowledge gained in such epidemiological studies guide us in outbreak expectations, limit antibiotic over-prescription, and enhance disease prevention. [ABSTRACT FROM AUTHOR]

Patient-delivered partner therapy (PDPT) allows index patients who test positive for Chlamydia trachomatis (Ct) to provide treatment to partners directly. PDPT is contingent upon an index being able to contact their partner. The aims of this study were to assess factors related to being able to contact a partner and being able to successfully deliver their treatment. Participants were Black men who have sex with women aged 15–26 enrolled in a community Ct screening/treatment program in New Orleans, LA who tested positive for Ct and completed a computer-assisted survey. Factors associated with the index's ability to contact their recent sex partner(s) and to successfully deliver PDPT to his partner(s) were compared by characteristics of the relationship. Of 104 young men who tested positive for Ct, the median age was 20.3 years and information was reported on 184 female partners, of whom 143 (77.7%) were deemed contactable by the index. Only the index wanting to have sex with the partner again was significantly associated with their ability to contact the partner (odds ratio [OR] 5.38, 95% confidence interval [CI] 2.18, 13.23). Only 72/184 (39.1%) partners received PDPT. The index being interested in sex with partner again (OR 2.54, 95% CI 1.23–5.27) was associated with greater odds of successful PDPT delivery whereas if index believed their partner had other partners, successful PDPT was less likely (OR 0.51, 95% CI 0.26–0.99). There was low agreement between an index's ability to contact their partner and the delivery of PDPT (kappa = 0.04 [−0.062, 0.143). Asking patients if they can recontact prior sexual parters may be insufficient to ensure that their partners receive PDPT. [ABSTRACT FROM AUTHOR]

Background:Chlamydia trachomatis is the most prevalent bacterial sexually transmitted pathogen in humans worldwide. Since chlamydial infection is largely asymptomatic with the potential for serious complications, a preventative vaccine is likely the most viable long-term answer to this public health threat. Cell-free protein synthesis (CFPS) utilizes the cellular protein manufacturing machinery decoupled from the requirement for maintaining cellular viability, offering the potential for flexible, rapid, and decentralized production of recombinant protein vaccine antigens. Methods: Here, we use CFPS to produce the full-length putative chlamydial type three secretion system (T3SS) needle-tip protein, CT584, for evaluation as a vaccine antigen in mouse models. High-speed atomic force microscopy (HS-AFM) (RIBM, Tsukuba, Japan) imaging and computer simulations confirm that CFPS-produced CT584 retains a native-like structure prior to immunization. Female mice were primed with CT584 adjuvanted with CpG-1826 intranasally (i.n.) or CpG-1826 + Montanide ISA 720 intramuscularly (i.m.), followed four weeks later by an i.m. boost before respiratory challenge with 104 inclusion forming units (IFU) of Chlamydia muridarum. Results: Immunization with CT584 generated robust antibody responses but weak cell-mediated immunity and failed to protect against i.n. challenge as demonstrated by body weight loss, increased lung weights, and the presence of high numbers of IFUs in the lungs. Conclusion: While CT584 was not a protective vaccine candidate, the speed and flexibility with which CFPS can be used to produce other potential chlamydial antigens make it an attractive technique for antigen production. [ABSTRACT FROM AUTHOR]

Background: Chlamydia abortus, as a pathogen of atypical pneumonia, is rare in humans, especially in HIV infection patients. Case presentation: We present the case of a 48-year-old man with a history of HIV infection who started high fever and developed pneumonia. The pathogen-targeted next-generation sequencing (ptNGS) results of bronchial lavage fluid showed Chlamydia abortus infection. Conclusion: This is the first report of Chlamydia abortus infection presented as atypical pneumonia in an AIDS patient. [ABSTRACT FROM AUTHOR]

Simple Summary: Chlamydial infections are a major threat to the health of koalas (Phascolarctos cinereus), an iconic Australian marsupial. Among the different chlamydial species, Chlamydia pecorum (C. pecorum) is the major pathogen infecting koalas, affecting their health and long-term survival, both in the wild and in captivity. Therefore, a deeper understanding of chlamydial infections, including their epidemiology, transmission mode, pathogenesis, host immune response, control, and prevention, is critical for the management of chlamydial infections in koalas. Herein, we discuss the current literature on C. pecorum infection in koalas, including the epidemiology, transmission, pathogenesis, immune response, and control strategies for chlamydial infection, with the aim of improving koala health and achieving effective conservation strategies. Chlamydial infections pose a significant threat to koala populations. Chlamydia pecorum (C. pecorum) remains the major chlamydial species affecting koala health, both in the wild and in captivity, and chlamydial infections are considered important factors affecting the long-term survival of koalas. A clear understanding of chlamydial infections, including the epidemiology, transmission mode, pathogenesis, immune response, control, and prevention thereof, is essential for improving the management of chlamydial infections in koalas. In this study, we discuss the important advances made in our understanding of C. pecorum infection in koalas, focusing on the epidemiology of chlamydial infections, and the transmission, pathogenesis, immune response, and control strategies for chlamydial infection, with the aim of improving koala health and achieving effective conservation strategies. [ABSTRACT FROM AUTHOR]

Background Chlamydia trachomatis testing and treatment strategies have not decreased infection rates, justifying need for a chlamydia vaccine. A murine study showed that a vaccine consisting of major outer membrane protein (MOMP) and polymorphic membrane proteins (Pmps) E, F, G, and H elicited protective immunity; studies on human cellular immune responses to Pmps are sparse. Methods Interferon gamma (IFN-γ) responses to these 5 proteins were measured by ELISPOT in peripheral blood mononuclear cells from women returning for treatment of a positive chlamydia test. Responses were compared in those with spontaneous chlamydia clearance versus persisting infection at baseline and no reinfection versus reinfection at a 3-month follow-up visit. Results IFN-γ response to 1 or more proteins was detected in 39% at baseline and 51.5% at follow-up, most often to PmpE and MOMP. IFN-γ responses to MOMP were detected less often at follow-up versus baseline in women with reinfection, but were maintained in those without reinfection. Women with spontaneous clearance had a higher magnitude of IFN-γ response to PmpE and MOMP. Conclusions IFN-γ responses to these 5 C. trachomatis vaccine candidate proteins were heterogenous and primarily directed against MOMP and PmpE. Spontaneous chlamydia clearance and absence of reinfection may be clinical correlates of protection. [ABSTRACT FROM AUTHOR]

Background: Chlamydia and gonorrhea notifications are rapidly rising in men who have sex with men (MSM). Currently, there are limited data on the prevalence of chlamydia and gonorrhea across various anatomical sites. Our study aimed to explore the prevalence, association and changing trends of urethral and rectal chlamydia and gonorrhea among MSM in Guangdong Province, China. Methods: We analyzed data among MSM attending sexually transmitted infections (STI) clinics in the Guangdong governmental sentinel network between 2018 and 2022. Chi-square tests were used to compare the difference, Join-point regressions for analyzing changing trends, and multivariate logistic regressions for examining associated factors. Results: We included 4856 men in the analysis. Rectal chlamydia significantly increased from 13.8% to 26.4% over the past 5 years (average annual percentage change [AAPC] 19.2%, 95%CI 1.0-40.6, p = 0.043). After adjusting for covariates, chlamydia infection positively associated with main venue used to seek sexual partners (aOR = 2.31, 95%CI 1.17–4.55), having regular sexual partners in the past 6 months (aOR = 3.32, 95%CI 1.95–5.64), receiving HIV counselling and testing services (aOR = 2.94, 95%CI 1.67–5.17), receiving peer education (aOR = 1.80, 95%CI 1.14–2.83), infection with syphilis (aOR = 2.02, 95%CI 1.02–4.01) and infection with gonorrhea (aOR 7.04, 95% CI 3.01–16.48). Gonorrhea infection positively associated with having regular sexual partners in the past 6 months (aOR = 3.48.95%CI 1.16–10.49), and infection with chlamydia (aOR 7.03, 95% CI 2.99–16.51). Conclusions: To conclude, our findings reveal a high prevalence of chlamydia infections among MSM, particularly in the rectal area. Comprehensive chlamydia and gonorrhea health services are necessary for MSM to improve sexual health. [ABSTRACT FROM AUTHOR]

Psittacosis, or parrot fever, is a zoonotic disease caused by Chlamydia species associated with birds. One of the causative agents of the disease is Chlamydia psittaci, which is commonly carried by psittacine and other bird species, can be highly pathogenic and virulent to humans. In Hong Kong, a city with high population density, psittacosis is a notifiable disease with over 60% of cases in the last decade resulting in hospitalization. However, the sources of transmission of C. psittaci and its prevalence in pet birds in Hong Kong are currently unknown. To evaluate the risks of psittacosis transmission through pet birds, we tested the presence of C. psittaci and determined its genotypes in samples obtained from 516 captive birds from households, pet shops, and a veterinary hospital in Hong Kong. Results revealed that five samples (0.97%), collected from budgerigars and cockatiels, were C. psittaci-positive, while four (80%) of them were obtained from pet shops. Our phylogenetic analysis revealed that all identified strains belonged to Genotype A and showed high similarity to other sequences of this genotype obtained from various geographical locations and host species, including mammals. Our findings provide evidence for the presence of Chlamydia psittaci and shed light on its sources in captive birds in Hong Kong. They highlight the potential zoonotic risks associated with this pathogen, which can affect both humans and wild birds. [ABSTRACT FROM AUTHOR]

To propagate within a eukaryotic cell, pathogenic bacteria hijack and remodulate host cell functions. The Gram-negative obligate intracellular Chlamydiaceae, which pose a serious threat to human and animal health, attach to host cells and inject effector proteins that reprogram host cell machineries. Members of the conserved chlamydial TarP family have been characterized as major early effectors that bind to and remodel the host actin cytoskeleton. We now describe a new function for the Chlamydia pneumoniae TarP member CPn0572, namely the ability to bind and alter the microtubule cytoskeleton. Thus, CPn0572 is unique in being the only prokaryotic protein that directly modulates both dynamic cytoskeletons of a eukaryotic cell. Ectopically expressed GFP-CPn0572 associates in a dose-independent manner with either cytoskeleton singly or simultaneously. In vitro, CPn0572 binds directly to microtubules. Expression of a microtubule-only CPn0572 variant resulted in the formation of an aberrantly thick, stabilized microtubule network. Intriguingly, during infection, secreted CPn0572 also colocalized with altered microtubules, suggesting that this protein also affects microtubule dynamics during infection. Our analysis points to a crosstalk between actin and microtubule cytoskeletons via chlamydial CPn0572. [ABSTRACT FROM AUTHOR]

Objective: Per- and polyfluoroalkyl substances (PFAS) alter immune function increasing infectious diseases risk. We examined the relationship between PFAS and chlamydia. Methods: A total of 3965 nonpregnant adults ages 18-39 years from the National Nutrition Examination Survey 2003-2016 cycles were included. Poisson regression with robust error variance estimated the prevalence ratio and 95% confidence intervals for the association between PFAS and chlamydia. Ag computationmodelwas used to examine PFASmixtures and chlamydia. Results: In adjusted age and sex-stratifiedmodels, an increase in PFASmixtures by one quintilewas associated with chlamydia in oldermales and younger females. Associationswere not observed before stratification. Conclusions: PFAS exposure associated with higher chlamydia prevalence, but only in stratified models suggesting biological differences by gender and age. However, small sample sizes could have affected the precision of our models. [ABSTRACT FROM AUTHOR]

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections continue to increase in the United States. Advancement in technology with point-of-care (POC) testing can improve the overall treatment of sexually transmitted infections (STI) in the emergency department (ED) by shortening the time to test result and administration of accurate treatment. The purpose of this study was to assess if the POC test reduced the rate of overtreatment for CT and/or NG compared to the standard-of-care (SOC) test. This retrospective cohort study included adult patients tested for CT and NG at two urban EDs between August 2020 and October 2022. This cohort excluded hospital admissions, elopement, pregnancy, rectal and oral samples, victims of sexual assault, and diagnoses for which antimicrobial treatment overlapped that of CT/NG. The primary outcome assessed overtreatment, defined as receiving treatment in the ED or a prescription prior to discharge for patients who tested negative for CT and/or NG. Secondary outcomes included undertreatment rates, overtreatment rates in select populations, test turnaround time, and ED length of stay (LOS). Of 327 patients screened, 97 patients were included in the SOC group and 100 in POC. Overtreatment for CT was provided in zero POC patients and 29 (29.9%) SOC patients (p < 0.001). NG was overtreated in 1 (1%) POC and 23 (23.7%) SOC (p < 0.001). POC was associated with undertreatment of CT and/or NG in two patients, compared to four patients tested with SOC. Overall, treatment was deemed inappropriate for 5 (5%) of those tested with POC, compared to 35 (36%) tested with SOC (p < 0.001). There was no difference in ED LOS (2.7 vs 3.01 h, p = 0.41). POC testing facilitated the return of results prior to patients being discharged from the ED. Compared to standard testing, POC improved appropriateness of CT and NG treatment by reducing the rates of overtreatment. [ABSTRACT FROM AUTHOR]

Background: Gastroschisis is a birth defect with the greatest risk among women <20 years of age. Methods: Pregnant women attending the University of Utah's Maternal‐Fetal Medicine Diagnostic Center between 2011 and 2017 for either their routine diagnostic ultrasound or referral were recruited (cases: pregnant women with fetal gastroschisis, n = 53 participated/57, 93%; controls: pregnant women without fetal abnormalities, n = 102 participated/120, 85%). A clinic coordinator consented and interviewed women and obtained a blood sample and prenatal medical records. We evaluated self‐reported maternal characteristics, risk factors, and infections. To assess pathogen seropositivity we used Serimmune's Serum Epitope Repertoire Analysis validated 35 pathogen panels and Chlamydia trachomatis and compared seropositivity to self‐report and prenatal medical record screening to assess sensitivity. Results: Cases were more likely to report a younger age at sexual debut (p = <0.01), more sexual partners (p = 0.02), being unmarried (p < 0.01), changing partners between pregnancies (p = <0.01), smoking cigarettes (<0.01), and a recent sexually transmitted infection (STI) (p = 0.02). No differences were observed for self‐report of illicit drug use or periconceptional urinary tract infections. Cases had a higher seropositivity for cytomegalovirus (p = 0.01). No differences were observed for herpes simplex I, II, or Epstein–Barr. Though based on small numbers, C. trachomatis seropositivity was highest in cases (17%) compared to controls (8.8%) with the highest proportion observed in case women <20 years of age (cases 33%; controls 0%). Any STI (self‐report or seropositivity) was also highest among cases <20 years of age (cases 47%; controls 0%). Among C. trachomatis seropositive women, self‐report and prenatal medical record sensitivity was 27.8% and 3%, respectively. Conclusions: Cases were more likely to engage in behaviors that can increase their risk of exposure to sexually transmitted pathogens. Case women <20 years of age had the highest proportion of C. trachomatis seropositivity and any STI. Prenatal medical records and self‐report were inadequate to identify a recent chlamydial infection whereas, the SERA assay is a novel approach for evaluating subclinical infections that may impact the developing embryo. [ABSTRACT FROM AUTHOR]

Introduction. International research suggests free online postal self-sampling for sexually transmitted infection (STI) testing is an acceptable alternative to clinic-based testing. A userpays online STI testing service exists in Aotearoa New Zealand, but acceptability among priority populations is unknown. Aim. To explore Māori and Pacific young people’s perspectives on online postal self-sampling for STI testing (as prospective service users). Methods. Four wānanga (knowledge-sharing forum) were held between November 2022 and May 2023 with Māori and Pacific participants aged 15–24 years who were recruited via youth-focused community organisations. Three facilitators guided discussions about STI testing and use of an online service. Inductive thematic analysis was used to analyse data generated from audio-recorded discussions, group work notes and facilitator field notes. Results. None of the 38 participants were aware of online STI testing and all considered it cost-prohibitive. Perceptions of online testing were mixed, and discussion about concerns outweighed perceived benefits. Three themes were identified: (i) potential to support autonomy (perceived benefits and positive features of self-sample collection kits); (ii) barriers and process-related concerns; and (iii) tailoring online STI testing to young people’s needs (facilitating engagement with online testing). Discussion. For online STI testing to be an accessible alternative to clinic-based testing for priority populations, cost, low awareness and other barriers in the testing pathway need to be addressed. Clinician follow-up on positive results and free treatment would be critical to ensure the cycle of best practice care is completed. Regardless of where testing is accessed, investment is needed to support young people’s knowledge of when, why and how to access a sexual health check. [ABSTRACT FROM AUTHOR]

Abstract Background Chlamydia and gonorrhea notifications are rapidly rising in men who have sex with men (MSM). Currently, there are limited data on the prevalence of chlamydia and gonorrhea across various anatomical sites. Our study aimed to explore the prevalence, association and changing trends of urethral and rectal chlamydia and gonorrhea among MSM in Guangdong Province, China. Methods We analyzed data among MSM attending sexually transmitted infections (STI) clinics in the Guangdong governmental sentinel network between 2018 and 2022. Chi-square tests were used to compare the difference, Join-point regressions for analyzing changing trends, and multivariate logistic regressions for examining associated factors. Results We included 4856 men in the analysis. Rectal chlamydia significantly increased from 13.8% to 26.4% over the past 5 years (average annual percentage change [AAPC] 19.2%, 95%CI 1.0-40.6, p = 0.043). After adjusting for covariates, chlamydia infection positively associated with main venue used to seek sexual partners (aOR = 2.31, 95%CI 1.17–4.55), having regular sexual partners in the past 6 months (aOR = 3.32, 95%CI 1.95–5.64), receiving HIV counselling and testing services (aOR = 2.94, 95%CI 1.67–5.17), receiving peer education (aOR = 1.80, 95%CI 1.14–2.83), infection with syphilis (aOR = 2.02, 95%CI 1.02–4.01) and infection with gonorrhea (aOR 7.04, 95% CI 3.01–16.48). Gonorrhea infection positively associated with having regular sexual partners in the past 6 months (aOR = 3.48.95%CI 1.16–10.49), and infection with chlamydia (aOR 7.03, 95% CI 2.99–16.51). Conclusions To conclude, our findings reveal a high prevalence of chlamydia infections among MSM, particularly in the rectal area. Comprehensive chlamydia and gonorrhea health services are necessary for MSM to improve sexual health.

The International Committee on Systematics of Prokaryotes (ICSP) discussed and rejected in 2020 a proposal to modify the International Code of Nomenclature of Prokaryotes to allow the use of gene sequences as type for naming prokaryotes. An alternative nomenclatural code, the Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode), which considers genome sequences as type material for naming species, was published in 2022. Members of the ICSP subcommittee for the taxonomy of the phylum Chlamydiae (Chlamydiota) consider that the use of gene sequences as type would benefit the taxonomy of microorganisms that are difficult to culture such as the chlamydiae and other strictly intracellular bacteria. We recommend the registration of new names of uncultured prokaryotes in the SeqCode registry.

Abstract Background The obligate intracellular bacterial family Chlamydiaceae comprises a number of different species that cause disease in various vertebrate hosts including humans. Chlamydia suis, primarily found in the gastrointestinal tract of pigs, is the only species of the Chlamydiaceae family to have naturally gained tetracycline resistance (TetR), through a genomic island (Tet-island), integrated into the middle of chromosomal invasin-like gene inv. Previous studies have hypothesised that the uptake of the Tet-island from a host outside the Chlamydiaceae family was a unique event, followed by spread among C. suis through homologous recombination. In vitro recombination studies have shown that Tet-island exchange between C. suis strains is possible. Our aim in this study was to gain a deeper understanding of the interclade recombination of the Tet-island, among currently circulating C. suis field strains compared to in vitro-generated recombinants, using published whole genome sequences of C. suis field strains (n = 35) and in vitro-generated recombinants (n = 63). Results We found that the phylogeny of inv better reflected the phylogeny of the Tet-island than that of the whole genome, supporting recombination rather than site-specific insertion as the means of transfer. There were considerable differences between the distribution of recombinations within in vitro-generated strains compared to that within the field strains. These differences are likely because in vitro-generated recombinants were selected for a tetracycline and rifamycin/rifampicin resistant background, leading to the largest peak of recombination across the Tet-island. Finally, we found that interclade recombinations across the Tet-island were more variable in length downstream of the Tet-island than upstream. Conclusions Our study supports the hypothesis that the occurrence of TetR strains in both clades of C. suis came about through interclade recombination after a single ancestral horizontal gene transfer event.

Chlamydiae are bacteria that are intriguing and important at the same time. The genus Chlamydia encompasses many species of obligate intracellular organisms: they can multiply only inside the cells of their host organism. Many, perhaps most animals have their own specifically adapted chlamydial species. In humans, the clinically most relevant species is Chlamydia trachomatis, which has particular importance as an agent of sexually transmitted disease. Pigs are the natural host of Chlamydia suis but may also carry Chlamydia abortus and Chlamydia pecorum. C. abortus and possibly C. suis have anthropozoonotic potential, which makes them interesting to human medicine, but all three species bring a substantial burden of disease to pigs. The recent availability of genomic sequence comparisons suggests adaptation of chlamydial species to their respective hosts. In cell biological terms, many aspects of all the species seem similar but non-identical: the bacteria mostly replicate within epithelial cells; they are taken up by the host cell in an endosome that they customize to generate a cytosolic vacuole; they have to evade cellular defences and have to organize nutrient transport to the vacuole; finally, they have to organize their release to be able to infect the next cell or the next host. What appears to be very difficult and challenging to achieve, is in fact a greatly successful style of parasitism. I will here attempt to cover some of the aspects of the infection biology of Chlamydia, from cell biology to immune defence, epidemiology and possibilities of prevention. I will discuss the pig as a host species and the species known to infect pigs but will in particular draw on the more detailed knowledge that we have on species that infect especially humans. [ABSTRACT FROM AUTHOR]

There is no vaccine against the major global pathogen Chlamydia trachomatis ; its different serovars cause trachoma in the eye or chlamydia in the genital tract. We did a clinical trial administering CTH522, a recombinant version of the C trachomatis major outer membrane molecule, in different dose concentrations with and without adjuvant, to establish its safety and immunogenicity when administered intramuscularly, intradermally, and topically into the eye, in prime-boost regimens. CHLM-02 was a phase 1, double-blind, randomised, placebo-controlled trial at the National Institute for Health Research Imperial Clinical Research Facility, London, UK. Participants were healthy men and non-pregnant women aged 18–45 years, without pre-existing C trachomatis genital infection. Participants were assigned into six groups by the electronic database in a pre-prepared randomisation list (A–F). Participants were randomly assigned (1:1:1:1:1) to each of the groups A–E (12 participants each) and 6 were randomly assigned to group F. Investigators were masked to treatment allocation. Groups A–E received investigational medicinal product and group F received placebo only. Two liposomal adjuvants were compared, CAF01 and CAF09b. The groups were intramuscular 85 μg CTH522-CAF01, or placebo on day 0 and two boosters or placebo at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (A); intramuscular 85 μg CTH522-CAF01, two boosters at day 28 and 112 with additional topical ocular administration of CTH522, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (B); intramuscular 85 μg CTH522-CAF01, two boosters at day 28 and 112 with additional intradermal administration of CTH522, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (C); intramuscular 15 μg CTH522-CAF01, two boosters at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (D); intramuscular 85 μg CTH522-CAF09b, two boosters at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (E); intramuscular placebo (F). The primary outcome was safety; the secondary outcome (humoral immunogenicity) was the percentage of trial participants achieving anti-CTH522 IgG seroconversion, defined as four-fold and ten-fold increase over baseline concentrations. Analyses were done as intention to treat and as per protocol. The trial is registered with ClinicalTrials.gov , NCT03926728 , and is complete. Between Feb 17, 2020 and Feb 22, 2022, of 154 participants screened, 65 were randomly assigned, and 60 completed the trial (34 [52%] of 65 women, 46 [71%] of 65 White, mean age 26·8 years). No serious adverse events occurred but one participant in group A2 discontinued dosing after having self-limiting adverse events after both placebo and investigational medicinal product doses. Study procedures were otherwise well tolerated; the majority of adverse events were mild to moderate, with only seven (1%) of 865 reported as grade 3 (severe). There was 100% four-fold seroconversion rate by day 42 in the active groups (A–E) and no seroconversion in the placebo group. Serum IgG anti-CTH522 titres were higher after 85 μg CTH522-CAF01 than 15 μg, although not significantly (intention-to-treat median IgG titre ratio groups A–C:D=5·6; p=0·062), with no difference after three injections of 85 μg CTH522-CAF01 compared with CTH522-CAF09b (group E). Intradermal CTH522 (group C) induced high titres of serum IgG anti-CTH522 neutralising antibodies against serovars B (trachoma) and D (urogenital). Topical ocular CTH522 (group B) at day 28 and 112 induced higher total ocular IgA compared with baseline (p<0·001). Participants in all active vaccine groups, particularly groups B and E, developed cell mediated immune responses against CTH522. CTH522, adjuvanted with CAF01 or CAF09b, is safe and immunogenic, with 85 μg CTH522-CAF01 inducing robust serum IgG binding titres. Intradermal vaccination conferred systemic IgG neutralisation breadth, and topical ocular administration increased ocular IgA formation. These findings indicate CTH522 vaccine regimens against ocular trachoma and urogenital chlamydia for testing in phase 2, clinical trials. The EU Horizon Program TRACVAC. [ABSTRACT FROM AUTHOR]

Background: Patient-delivered partner therapy (PDPT) involves providing a prescription or medication to a patient diagnosed with chlamydia to pass to their sexual partner/s. Barriers to PDPT include uncertainty about its integration into clinical practice and permissibility. In Victoria, Australia, the Department of Health provides clinical guidance for PDPT (updated in 2022). We explored health practitioner views on the usefulness of the updated guidance for providing PDPT. Methods: We conducted an online survey (12 December 2022 to 2 May 2023) of health practitioners who primarily work in Victoria and can prescribe to treat chlamydia. The survey displayed excerpts from the guidance, and asked closed and free-text questions about its ability to address barriers to PDPT. Quantitative data were descriptively analysed, complemented by conventional content analysis of qualitative data. Results: Of a total of 49 respondents (66.7% general practitioners), 74.5% were aware of PDPT, and 66.7% had previously offered PDPT. After viewing excerpts of the guidance, >80% agreed it could support them to identify patients eligible/ineligible for PDPT, and 66.7% indicated they would be comfortable to offer PDPT. The guidance was viewed as helpful to address some barriers, including complicated documentation (87.7%) and medico-legal concerns (66.7%). Qualitative data highlighted medico-legal concerns by a minority of respondents. Some raised concerns that the guidance recommended prescribing azithromycin, despite doxycycline being first-line chlamydia treatment. Conclusions: The guidance was largely viewed as supportive for PDPT decision-making. There is scope for further refinements and clarifications, and wider dissemination of the guidance. Patient-delivered partner therapy (PDPT) involves providing a prescription or medication to a patient with chlamydia to pass to their sexual partner/s, but clinicians have expressed uncertainty about its permissibility and integration into practice. We surveyed clinician perspectives on updated health authority guidance for PDPT; finding they largely viewed it as supportive for PDPT decision-making and addressed some practical barriers. Low awareness of the updated guidance, and medico-legal concerns, for some, highlight scope for further dissemination and clarification of PDPT permissibility. [ABSTRACT FROM AUTHOR]

The association between human papillomavirus (HPV) and other sexually transmitted infections (STIs) in anal lesions still remains unclear. Aim of the study was to evaluate the prevalence of simultaneous infection of HPV and Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, and Trichomonas vaginalis in individuals screened for HPV anal infection. A total of 507 anal samples were tested for both anal HPV and STIs: 16% resulted positive for one or more non‐HPV STIs. Specifically, C. trachomatis, M. genitalium, and N. gonorrhoeae were detected in 8%, 5%, and 4% of cases, respectively. Two groups were considered, including a positive STI group and a negative STI group. The prevalence of HPV was similar in patients in both groups: high risk (HR)‐HPV and low risk (LR)‐HPV were 67% and 53% versus 62% (p = 0.361) and 54% (p = 0.864) of patients, respectively. However, HPV 16, 18, 35, 51, 59, and 69 were significantly more frequent in patients tested positive for other STIs versus HPV infection alone (p < 0.05). No significant differences between the two groups were observed in vaccination coverage, 28% versus 32% (p = 0.463), and HIV status, 86% versus 84% (p = 0.658). The study shows that the overall HPV status is not directly correlated to other STIs in the investigated population, except for certain HPV types, including HR‐HPV 16, reinforcing the urge for a greater vaccination coverage. [ABSTRACT FROM AUTHOR]

Objective: Metagenomic next-generation sequencing (mNGS) was used to analyze the etiological distribution of refractory pneumonia in children. We compared its efficacy in pathogen diagnosis against traditional methods to provide a basis for clinical adjustment and treatment. Methods: A total of 60 children with refractory pneumonia treated at the Department of Respiratory Medicine, Children's Hospital Affiliated with the Capital Institute of Paediatrics, from September 2019 to December 2021 were enrolled in this study. Clinical data (including sex, age, laboratory tests, complications, and discharge diagnosis) and lower respiratory tract specimens were collected, including bronchoalveolar lavage fluid (BALF), deep sputum, pleural effusion, lung abscess puncture fluid, traditional respiratory pathogens (culture, acid-fast staining, polymerase chain reaction, serological testing, etc.), and mNGS detection methods were used to determine the distribution of pathogens in children with refractory pneumonia and to compare the positive rate and diagnostic efficiency of mNGS and traditional pathogen detection for different types of pathogens. Results: Among the 60 children with refractory pneumonia, 43 specimens were positive by mNGS, and 67 strains of pathogens were detected, including 20.90% (14 strains) of which were Mycoplasma pneumoniae, 11.94% (8 strains) were Streptococcus pneumoniae, 7.46% (5 strains) were cytomegalovirus, and 5.97% (4 strains) were Candida albicans. Thirty-nine strains of Mycoplasma pneumoniae (41.03%, 16 strains), Streptococcus pneumoniae (10.26%, 4 strains), Candida albicans (7.69%, 3 strains), and Aspergillus (5.13%, 2 strains) were detected using traditional methods. The positive rate of mNGS detection was 90.48%, and the positive rate of the traditional method was 61.90% (p = 0.050), especially for G+ bacteria. The positive rate of mNGS was greater than that of traditional methods (p < 0.05), but they had no significant difference in detecting G-bacteria, viruses, fungi, or Mycoplasma/Chlamydia. Among the 60 patients, 21 had mixed infections, 25 had single infections, and the other 14 had unknown pathogens. Mycoplasma pneumoniae was most common in both mixed infections and single infections. The sensitivity, specificity, positive predictive value, and negative predictive value of mNGS were 95.45, 37.50, 80.77, and 75.00%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of the traditional methods were 72.72, 62.50, 84.21, and 45.45%, respectively. The clinical compliance of mNGS was 80.00%, and that of the traditional method was 70.00%. The sensitivity and negative predictive value of mNGS were high, and the difference in the sensitivity for detecting G+ bacteria was statistically significant (p < 0.05). However, the differences in G-bacteria, fungi, and Mycoplasma/Chlamydia were not statistically significant (p > 0.05). Due to the small sample size, statistical analysis could not be conducted on viral infections. Conclusion: mNGS has higher overall efficacy than traditional methods for the etiological diagnosis of refractory pneumonia in children. The application of mNGS can significantly improve the detection rate of pathogens in children with refractory pneumonia. The sensitivity and negative predictive value of mNGS for detecting G+ bacteria are greater than those of other methods, and it can exclude the original suspected pathogenic bacteria. Unnecessary antibiotic use was reduced, but there was no statistically significant difference in G-bacteria, fungi, or Mycoplasma/Chlamydia. [ABSTRACT FROM AUTHOR]

Chlamydiae are a large group of obligate endosymbionts of eukaryotes that includes the Chlamydiaceae family, comprising several animal pathogens. Among Chlamydiaceae, Chlamydia trachomatis causes widespread ocular and urogenital infections in humans. Like many bacterial pathogens, all Chlamydiae manipulate host cells by injecting them with type III secretion effector proteins. We previously characterized the C. trachomatis effector CteG, which localizes at the host cell Golgi and plasma membrane during distinct phases of the chlamydial infectious cycle. Here, we show that CteG is a Chlamydiaceae-specific effector with over 60 homologs phylogenetically categorized into two distinct clades (CteG I and CteG II) and exhibiting several inparalogs and outparalogs. Notably, cteG I homologs are syntenic to C. trachomatis cteG, whereas cteG II homologs are syntenic among themselves but not with C. trachomatis cteG. This indicates a complex evolution of cteG homologs, which is unique among C. trachomatis effectors, marked by numerous events of gene duplication and loss. Despite relatively modest sequence conservation, nearly all tested CteG I and CteG II proteins were identified as type III secretion substrates using Yersinia as a heterologous bacterial host. Moreover, most of the type III secreted CteG I and CteG II homologs were delivered by C. trachomatis into host cells, where they localized at the Golgi region and cell periphery. Overall, this provided insights into the evolution of bacterial effectors and revealed a Chlamydiaceae family of type III secreted proteins that underwent substantial divergence during evolution while conserving the capacity to localize at specific host cell compartments. [ABSTRACT FROM AUTHOR]

Objectives: The performance of the new Respiratory Pathogen panel (fluorescent probe melting curve, FPMC) for the qualitative detection of 12 organisms (chlamydia pneumoniae, mycoplasma pneumoniae, adenovirus, influenza A virus, influenza B virus, parainfluenza virus, rhinovirus, etc.) was assessed. Methods: Prospectively collected nasopharyngeal swab (NPS) and sputum specimens (n = 635) were detected by using the FPMC panel, with the Sanger sequencing method as the comparative method. Results: The overall percent concordance between the FPMC analysis method and the Sanger sequencing method was 100% and 99.66% for NPS and sputum specimens, respectively. The FPMC testified an overall positive percent concordance of 100% for both NPS and sputum specimens. The FPMC analysis method also testified an overall negative percent concordance of 100% and 99.38% for NPS and sputum specimens, respectively. Conclusions: The FPMC analysis method is a stable and accurate assay for rapid, comprehensive detecting for respiratory pathogens. [ABSTRACT FROM AUTHOR]

Objective: To survey the prevalence of pathogens in shelter‐housed cats with active ocular surface disease (OSD). Animals Studied: A total of 255 shelter‐housed domestic cats with evidence of active OSD. No normal, unaffected cats were sampled. Procedure(s): OSD scoring was performed on cats with active OSD. Combined oropharyngeal/conjunctival swabs were submitted for rt‐PCR/PCR for feline herpesvirus (FHV‐1), feline calicivirus (FCV), Chlamydia spp. (CHL), Bordetella bronchiseptica (BORD), and Mycoplasma spp. (MYC). Results: Pathogens were detected as follows: 76.4% (195/255) MYC, 57.6% (147/255) FHV‐1, 42.7% (109/255) FCV, 26.7% (68/255) CHL, and 5.5% (14/255) BORD. Monoinfections affected 21.1% (54/255) animals, with MYC being the most common monoinfection (12.5%, 32/255), followed by FHV‐1 (4.7%, 12/255), followed by CHL (2.4%, 6/255), followed by FCV (1.6%, 4/255), with no animals having a BORD monoinfection. Dual infections affected 36.4% of animals (93/255), with MYC detected in 30.1% (77/255) dual infections and FCV detected in 12.9% (33/255) dual infections. Dual infections with MYC and FCV together were detected in 9.8% (25/255) animals. Many animals (35.3%, 90/255) were found to be affected by 3 or more pathogens, and 7.1% (18/255) animals had no pathogens detected. OSD scores were not influenced by any variable assessed, including the number and type of pathogens detected. Conclusion: MYC, FHV‐1, FCV, and CHL were commonly detected in this group of animals with OSD. Both MYC and FCV (alone or in combination with each other) were detected in multiple animals with active OSD, supporting prior evidence that either may independently act as a primary ocular surface pathogen. [ABSTRACT FROM AUTHOR]

Objective: We report the prevalence, characteristics and clinical outcomes of women with sexually transmitted infections (STIs) in pregnancy in the Western Sydney Local Health District (WSLHD) serving a large culturally and socio‐economically diverse community in New South Wales (NSW), Australia, over the last 10 years. Methods: A retrospective cohort study of all pregnant women booked for antenatal care at three hospitals in WSLHD between September 2012 and August 2022 inclusive. Characteristics and birth outcomes associated with STIs diagnosed in pregnancy (chlamydia, gonorrhea, and syphilis) are reported using multivariable logistic regression adjusting for relevant confounders. Results: During 2012–2022, there were 102 905 births and 451 women (0.44%) with an STI diagnosis during pregnancy. The number of women with a history of chlamydia prior to their current pregnancy has increased over the last 10 years (P < 0.001). STIs in pregnancy were more common in younger women aged <20 years (adjusted odds ratio [aOR] 7.30, 95% confidence interval [CI] 5.04–10.57), 20–24 years (aOR 3.12, 95% CI 2.46–3.96), and >40 years (adj OR 1.67, 95% CI 1.07–2.59), in women with body mass index >30 (aOR 1.73, 95%CI 1.37–2.19), and those who smoked (aOR 2.24, 95% CI 1.71–2.94) and consumed alcohol (aOR 3.14, 95% CI 1.88–5.23) and illicit drugs (aOR 2.10, 95% CI 1.31–3.36). STIs in pregnancy were borderline associated with stillbirth (aOR 2.19 95% CI 0.90–5.36) but did not have a significant impact on preterm birth (aOR 1.21, 95% CI 0.87–1.68), admission to neonatal intensive care unit (NICU) (aOR 1.02, 95% CI 0.77–1.34), or having a small‐for‐gestational‐age (SGA) baby (aOR 0.97, 95% CI 0.74–1.27). Conclusions: Sociodemographic factors such as age, weight, smoking, and alcohol and drug use, were associated with the STI incidence in pregnancy. While the latter did not have an impact on preterm birth, NICU admission, and SGA in our cohort, there was a borderline association with stillbirth. Future research should identify barriers and facilitators to testing in a multicultural population and understanding the drivers of higher rates of STIs in certain population groups. Synopsis: We identified sociodemographic factors associated with a higher risk of testing positive for STIs in pregnancy. STI in pregnancy was borderline associated with stillbirth. [ABSTRACT FROM AUTHOR]

There is increasing interest in improving routine HIV screening in emergency departments and increasing HIV cotesting rates among patients tested for sexually transmitted infections (STIs), who are considered at elevated risk of acquiring HIV. This is a retrospective review of all ED encounters at a large, urban emergency departments with an existing HIV screening program for seven months before (November 1, 2018, to May 30, 2019) and after (June 1 to December 31, 2019) the implementation of a best practice advisory prompting universal HIV and syphilis screening. The study included 14,767 unique encounters, with 3,982 pre-implementation encounters and 10,785 post-implementation. After implementation, HIV testing increased 242%, from 2,851 tests to 9,757, and syphilis testing increased 326%, from 2,191 tests to 9,330. The proportion of encounters for urogenital STI testing without HIV cotesting decreased by 10.3%, from 43.6% to 33.3%. An automated electronic medical record (EMR) prompt can have a huge impact on both HIV and syphilis testing rates, as well as the rate of missed opportunities for cotesting among patients undergoing STI testing. Hospitals should support screening with automated alerts to help meet quality metrics, improve screening rates, and reduce missed opportunities for screening in vulnerable patients. • Novel means of increasing HIV screening uptake in emergency departments are needed. • Introduction of an automated alert increased HIV screening by 242%. • The automated alert increased syphilis screening by 326%. • Missed HIV cotesting with gonorrhea and chlamydia testing decreased by 10.3%. • An automated alert may decrease age and racial bias in HIV and syphilis screening. [ABSTRACT FROM AUTHOR]

Chlamydia infections commonly afflict both humans and animals, resulting in significant morbidity and imposing a substantial socioeconomic burden worldwide. As an obligate intracellular pathogen, Chlamydia interacts with other cell organelles to obtain necessary nutrients and establishes an intracellular niche for the development of a biphasic intracellular cycle. Eventually, the host cells undergo lysis or extrusion, releasing infectious elementary bodies and facilitating the spread of infection. This review provides insights into Chlamydia development and host cell responses, summarizing the latest research on the biphasic developmental cycle, nutrient acquisition, intracellular metabolism, host cell fates following Chlamydia invasion, prevalent diseases associated with Chlamydia infection, treatment options, and vaccine prevention strategies. A comprehensive understanding of these mechanisms will contribute to a deeper comprehension of the intricate equilibrium between Chlamydia within host cells and the progression of human disease. [ABSTRACT FROM AUTHOR]

Background: A systematic review on acceptability, feasibility, equity and resource use was conducted as part of updating recommendations from the Public Health Agency of Canada on prenatal screening for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG). Methods: Information sources, including MEDLINE® All, Embase and Cochrane CENTRAL (January 2003-January 2021) electronic databases were searched for studies that assessed acceptability, feasibility, equity and resource use of screening for CT or NG in pregnant persons aged =12 years. The Risk of Bias Assessment Tool for Non-Randomized Studies was used for quality assessment and a narrative synthesis was prepared. Results: Of the 1,386 records identified, nine observational studies (approximately 5,000 participants) and three economic evaluations met the inclusion criteria. In general, pregnant persons and healthcare providers accepted screening. Most pregnant persons and partners supported universal testing for CT. Pregnant persons preferred non-invasive sampling Methods. Inequities in feasibility (accessibility to screening) exist in certain populations. Studies have shown that targeted screening can miss cases. Screening all pregnant persons for CT has net cost savings compared to no screening. Limitations include not identifying eligible literature on acceptability of prenatal screening for NG among partners of pregnant persons and some studies with increased risk populations that restrict the generalizability of the findings highlighting areas for future research. Conclusion: Prenatal screening for CT and NG is generally acceptable among pregnant persons and healthcare providers. Evidence has shown that targeted screening can miss cases. The findings were included when updating PHAC's recommendations on prenatal screening for CT and NG. This work was presented at the Society of Obstetricians and Gynaecologists of Canada's 2024 Annual Clinical and Scientific Conference in Edmonton, Alberta. [ABSTRACT FROM AUTHOR]

Simple Summary: Birds are known to be carriers of ticks, both Argasidae and Ixodidae, which often harbor bacterial pathogens. Climatic changes observed in the last years have influenced tick distributions in several geographic areas and the migratory behaviors of many avian species; consequently, wild birds can be responsible for the introduction of ticks and relative pathogens, most of which are zoonotic, in new environments. Some studies have been carried out to detect tick-borne bacteria in ticks removed from birds worldwide, but surveys on the presence of these pathogens directly in avifauna are very scanty. This study evaluated the occurrence of tick-borne bacteria, such as Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi sensu lato, Chlamydia psittaci, Coxiella burnetii, Ehrlichia canis, Francisella tularensis, and Rickettsia spp., in avian spleen samples, and the obtained results suggested that wild avifauna may be involved in the epidemiology of some of the investigated pathogens. Birds are known to be carriers of ticks infected by tick-borne pathogens, including bacteria. However, not many studies have been carried out on avian tissues to detect these agents. The aim of the present survey was to investigate, using PCR, the presence of Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi sensu lato, Chlamydia psittaci, Coxiella burnetii, Ehrlichia canis, Francisella tularensis, and Rickettsia spp. in the spleens collected from 300 wild birds of different orders and species from Central Italy. A total of 53 (17.67%) samples were PCR positive for at least one investigated pathogen. One (0.33%) bird was positive for Bartonella spp., five (1.67%) birds were positive for C. burnetii, eleven (3.67%) for B. burgdorferi s.l., and thirty-six (12%) for C. psittaci. No coinfection was detected. All samples were negative for A. phagocytophilum, E. canis, F. tularensis, and Rickettsia spp. The findings showed that wild birds may harbor different zoonotic tick-borne bacteria; therefore, they can contribute to the diffusion of these agents. [ABSTRACT FROM AUTHOR]

The clinical severity of Chlamydia psittaci infection ranges from asymptomatic to severe pneumonia. Diagnosis poses challenges due to its similarity to other respiratory infections. Treatment includes tetracyclines, macrolides, and fluoroquinolones, with limited evidence on the efficacy of omadacycline. We report a case of an 86-year-old male with severe psittacosis treated with omadacycline, resulting in significant improvement. This highlights the necessity for further research on omadacycline's role in psittacosis treatment. [ABSTRACT FROM AUTHOR]

Background: The general practice out-of-hours (GPOOH) service is under pressure to treat more patients in less time, while reducing referrals and minimising diagnostic errors. Point-of-care (POC) testing involves rapid clinical tests that can be used to generate results during the consultation, and has the potential to facilitate managing these competing demands safely. Aim: To describe current availability of POC tests in GPOOH in Scotland, and identify barriers, enablers, benefits, and drawbacks to its use. Design & setting: Cross-sectional mixed-methods study, which surveyed opinions of clinicians working in the GPOOH service in NHS Scotland. Method: An electronic questionnaire was developed, designed, piloted, and distributed to clinicians, which had closed questions and areas for free text. Results: In total, 142 responses were received. Urine dipstick testing (99.2%), pregnancy tests (98.5%), oxygen saturation (97.7%), and blood glucose testing (93.9%), were the only POC tests commonly available in GPOOH in NHS Scotland. There was strongest support for the provision of POC tests, particularly C-reactive protein (CRP; 79.4%), strep A (76.0%), and D-dimer (75.2%). Responders felt that POC tests would improve confidence (92.3%) and safety (89.8%) surrounding clinical decision making, improve patient satisfaction (80.6%), and reduce hospital and secondary care referrals (77.5%). Barriers to POC test use were availability of the test kits and machines (94.5%), training requirements on how to use the machine (71.1%) and interpret results (56.3%), and time to do the test (62.0%). Conclusion: Few POC tests are in regular use in GPOOH in Scotland. GPOOH clinicians are supportive of using POC testing. They identified a number of benefits to its use, with very few drawbacks. Increased provision of POC testing in GPOOH in NHS Scotland should be considered urgently. [ABSTRACT FROM AUTHOR]

Objectives: Chlamydia trachomatis (chlamydia) is one of the most reported bacterial sexually transmitted infections (STI) worldwide. Chlamydia can cause long term complications such as pelvic inflammatory disease (PID), ectopic pregnancy (EP) and tubal factor infertility (TFI). Changing testing strategies, for example reduced asymptomatic testing, influence chlamydia surveillance, highlighting the need for exploring alternative ways of monitoring chlamydia. We investigated the possibility of introducing routine surveillance of chlamydia related long term complications. Methods: A qualitative study including 15 in-depth interviews with a purposive sample of gynaecologists, general practitioners (GP), sexual health and emergency doctors was conducted in the Netherlands in 2021–2022. A semi-structured interview guide focused on experiences with diagnosis and registration of PID, EP and TFI and how a change in asymptomatic chlamydia testing strategy might influence this. Interviews were transcribed and analysed using a thematic approach. Results: Analysis showed that gynaecologists most frequently reported diagnosing PID, EP and TFI. Other professions rarely diagnose these complications, with emergency doctors only diagnosing EP. Most respondents reported unique registration codes for PID and EP, but the coding for TFI is more ambiguous. They reflected that diagnosis and registration of PID, EP and TFI are handled differently within their professions. Most respondents acknowledged registration in diagnostic codes as a useful surveillance tool. They expressed concerns in representativeness (e.g. differences in interpretation of diagnosis criteria) and data quality for surveillance. Conclusions: Patient files of gynaecologists are likely to be most complete for monitoring trends of diagnosed chlamydia related long term complications in the Netherlands. However, when establishing a chlamydia complication surveillance system, professionals should be engaged in further standardizing diagnosis and registration practices. This will improve the quality and interpretability of complication surveillance and facilitate comparison between countries. [ABSTRACT FROM AUTHOR]

Background: We investigated the presence of Chlamydia psittaci in poultry and the environment in live poultry wholesale markets in Changsha during 2021–2022 and conducted a phylogenetic analysis to understand its distribution in this market. Methods: In total, 483 samples were analyzed using real-time polymerase chain reaction and 17 C. psittaci-positive samples using high-throughput sequencing, BLAST similarity, and phylogenetic analysis. Results: Twenty-two out of 483 poultry and environmental samples were positive for C. psittaci (overall positivity rate: 4.55%) with no difference in positivity rates over 12 months. Chlamydia psittaci was detected at 11 sampling points (overall positivity rate: 27.5%), including chicken, duck, and pigeon/chicken/duck/goose shops, with pigeon shops having the highest positivity rate (46.67%). The highest positivity rates were found in sewage (12.5%), poultry fecal (7.43%), cage swab (6.59%), avian pharyngeal/cloacal swab (3.33%), and air (2.29%) samples. The ompA sequences were identified in two strains of C. psittaci, which were determined to bear genotype B using phylogenetic analysis. Thus, during monitoring, C. psittaci genotype B was detected in the poultry and environmental samples from the poultry wholesale market in Changsha. Conclusions: To address the potential zoonotic threat, C. psittaci monitoring programs in live poultry markets should be enhanced. [ABSTRACT FROM AUTHOR]

Sexually transmitted infections (STIs) continue to increase in the United States with more than 2.5 million cases of gonorrhea, chlamydia, and syphilis reported to the Centers for Disease Control and Prevention in 2022. Untreated STIs in women can lead to adverse outcomes, including pelvic inflammatory disease, infertility, chronic pelvic pain, and pregnancy complications such as ectopic pregnancy, early pregnancy loss, stillbirth, and neonatal transmission. STI-related guidelines can be complex and are frequently updated, making it challenging to stay informed on current guidance. This article provides high-yield updates to support clinicians managing STIs by highlighting changes in screening, diagnosis, and treatment. One important topic includes new guidance on syphilis screening, including a clarified description of high community rates of syphilis based on Healthy People 2030 goals, defined as a case rate of primary or secondary syphilis > 4.6 per 100,000. Reproductive aged persons living in counties above this threshold should be offered syphilis screening. Additionally, American College of Obstetricians & Gynecologists now recommends syphilis screening three times during pregnancy regardless of risk—at the first prenatal visit, during the third trimester, and at delivery. In addition, new guidance to support consideration for extragenital screening for gonorrhea and chlamydia in women at sites such as the anus and pharynx is discussed. Other topics include the most recent chlamydia, gonorrhea, trichomoniasis, and pelvic inflammatory disease treatment recommendations; screening and treatment guidance for Mycoplasma genitalium; genital herpes screening indications and current diagnostic challenges; and the diagnosis and management of mpox in women and during pregnancy. [ABSTRACT FROM AUTHOR]

Simple Summary: In order to understand the prevalence of respiratory diseases in urban stray cats in Shanghai and provide scientific evidence for the development of targeted prevention and control strategies for respiratory diseases in stray cats, we performed a molecular survey in Shanghai in 2022. A total of 374 stray cats were screened against six respiratory pathogens. Out of the 374 samples, 146 tested positive. Mycoplasma felis exhibited the highest positivity rate at 18.72% (70/374), followed by Chlamydia felis at 11.76% (44/374), feline calicivirus at 3.74% (14/374), feline herpesvirus type-1 at 3.48% (13/374), and Bordetella bronchiseptica at 1.34% (5/374); influenza A virus was not detected. Mycoplasma felis and Chlamydia felis were the primary causative agents of respiratory infections in urban stray cats, with Mycoplasma felis demonstrating a notably higher positivity rate compared to other respiratory pathogens and frequently co-infecting with Chlamydia felis and feline calicivirus. The positivity rate of Mycoplasma felis was elevated during the summer, autumn, and winter seasons, with no significant variance between seasons. These results highlight a substantial overall prevalence of respiratory pathogens in urban stray cats in the Shanghai region, characterized by seasonal patterns and concurrent infections with other pathogens. These findings suggest the need for comprehensive prevention and control measures to address respiratory pathogen infections in urban stray cats in the Shanghai area. Urban stray cats are cats without owners that survive in the wild for extended periods of time. They are one of the most common stray animals in cities, and as such, monitoring the pathogens carried by urban stray cats is an important component of urban epidemiological surveillance. In order to understand the prevalence of respiratory diseases in urban stray cats in Shanghai and provide scientific evidence for the development of targeted prevention and control strategies for respiratory diseases in stray cats, we collected 374 ocular, nasal, and oropharyngeal swabs from urban stray cats in Shanghai from January 2022 to December 2022. After RNA extraction, we used real-time PCR to detect six respiratory pathogens, including influenza A virus, feline calicivirus, feline herpesvirus type 1, Mycoplasma, Chlamydia, and Bordetella bronchiseptica. The results showed that among the 374 samples, 146 tested positive, with a positivity rate of 39.04%. The highest positivity rate was observed for Mycoplasma felis at 18.72% (70/374), followed by Chlamydia felis at 11.76% (44/374), feline calicivirus at 3.74% (14/374), feline herpesvirus 1 at 3.48% (13/374), Bordetella bronchiseptica at 1.34% (5/374), and influenza A virus was not detected. The highest positivity rate for Mycoplasma felis was in Minhang District at 31.94% (23/72), while Chlamydia felis and Bordetella bronchiseptica had the highest positivity rates in Jiading District at 23.53% (8/34) and 5.88% (2/34), respectively. The highest positivity rates for feline calicivirus and feline herpesvirus 1 were both observed in Qingpu District, at 14.46% (12/83) and 9.64% (8/83), respectively. A total of 36 samples showed mixed infections with two or more pathogens, with Mycoplasma felis being involved in 32 of these mixed infections, with the highest number of mixed infections being with Chlamydia felis at 25 samples. Respiratory pathogen positivity was detected throughout the year, with peak detection rates in summer and winter. The positivity rates of cat respiratory pathogens in different seasons showed statistical differences (χ2 = 27.73, p < 0.01). There was no statistical difference in the positivity rates of respiratory pathogens between cats of different genders (χ2 = 0.92, p > 0.05). The positivity rates of respiratory pathogens in cats of different age groups showed statistical differences (χ2 = 44.41, p < 0.01). Mycoplasma felis and Chlamydia felis were the main pathogens causing respiratory infections in stray cats, with Mycoplasma felis showing a much higher positivity rate than other respiratory pathogens and often co-infecting with Chlamydia felis and feline calicivirus. The positivity rate of Mycoplasma felis was high in summer, autumn, and winter, with no statistical difference between seasons. These results indicate a serious overall prevalence of respiratory pathogens in urban stray cats in the Shanghai area, showing seasonal trends and mixed infections with other pathogens. These findings suggest the need for comprehensive prevention and control measures to address respiratory pathogen infections in urban stray cats in the Shanghai area. [ABSTRACT FROM AUTHOR]

Background: While the connection between alcohol and risky behavior is well known, a clear correlation between alcohol misuse and contracting sexually transmitted infections (STIs) has not been determined. The 4-question CAGE questionnaire—the acronym stands for attitudes and activities related to alcohol use—is often administered at primary care annual visits to screen patients for alcohol abuse. This study assessed the relationship between CAGE scores and STI results to determine if the CAGE questionnaire could help determine the need for STI screening at annual visits. Methods: All patients who received a CAGE screening from 2015 to 2022 at a Gulf South health system were included in the analysis. The primary outcome of the study was the relationship between a positive CAGE score (a score 2) and a positive STI result. STIs included in the primary analysis were human immunodeficiency virus (HIV), hepatitis B, syphilis, chlamydia, gonorrhea, and trichomoniasis. The correlation between a positive CAGE score and hepatitis C was examined as a secondary outcome. Results: A total of 40,022 patients received a CAGE screening during the study period, and 757 (1.9%) scored 2 on the CAGE questionnaire. Significant associations were found between a positive CAGE score and hepatitis B (odds ratio [OR]=2.69, 95% CI 1.91, 3.80; P<0.001), gonorrhea (OR=5.43, 95% CI 1.80, 16.39; P=0.003), and hepatitis C (OR=2.10, 95% CI 1.57, 2.80; P<0.001). No associations were found between a positive CAGE score and HIV, chlamydia, or trichomoniasis. No patients with a CAGE score 2 had a syphilis diagnosis; therefore, no syphilis analysis was possible. Conclusion: Based on the results of this study, patients with a CAGE score 2 may benefit from screening for hepatitis B, hepatitis C, and gonorrhea at their primary care annual visit. Early STI detection could lead to prompt treatment and prevent further transmission and complications. [ABSTRACT FROM AUTHOR]

Background: We investigated awareness and use of doxycycline post-exposure prophylaxis (doxyPEP) in the US. DoxyPEP has preventative benefits for bacterial STIs among people assigned male at birth. We considered how individual, interpersonal and social determinants of health, such as state-level LGBTQ equality, impact doxyPEP awareness. Methods: We conducted an online snapshot cross-sectional survey in June 2023. Survey questions included demographics, sexual and substance use behaviours, and socio-environmental factors, and provided a short explanation of doxyPEP, with questions regarding prior awareness and use. Results: Among a racially diverse sample of 196 participants (median age 33 years), 94% identified as cisgender men, 26% were aware of doxyPEP, whereas only 14 (7%) had ever used it. Factors significantly associated with awareness included being college educated (OR 2.50, 95% CI 1.09–5.74), a past year bacterial STI (OR 4.20, 95% CI 1.97–8.89), having discussed HIV pre-exposure prophylaxis with a health care provider (OR 3.88, 95% CI 1.99–7.57) and having taken HIV pre-exposure prophylaxis (OR 2.29, 95% CI 1.11–4.70). Socio-environmental factors associated with doxyPEP awareness included living in a large urban city (OR 2.14, 95% CI 1.12–4.10) and living in a state with higher levels of LGBTQ policy equality (OR 2.18, 95% CI 1.07–4.44). Conclusions: Considering the disproportionate impact of bacterial STIs on men who have sex with men, especially those living in lower LGBTQ equality regions, such as the Southern US, our study emphasises how socio-environmental factors may limit awareness and uptake of novel biomedical approaches that have the potential to prevent morbidity and enhance sexual health. Bacterial STIs are on the rise in the US. Although people assigned male at birth can benefit from taking an antibiotic soon after sex (doxycycline post-exposure prophylaxis) to prevent STIs, we found that only one-quarter of participants surveyed were aware of doxycycline post-exposure prophylaxis; those living in places with LGBTQ inequality were less likely to be aware. Increased awareness of new prevention approaches among those most at risk is crucial to increased uptake. [ABSTRACT FROM AUTHOR]