Rectal Chlamydia trachomatis Infection: A Narrative Review of the State of the Science and Research Priorities

Changes in Oral and Anal Sex With Opposite-Sex Partners Among Sexually Active Females and Males Aged 15 to 44 Years in the United States: National Survey of Family Growth, 2011-2019

BACKGROUND

Oral and anal sex with opposite-sex partners is common and associated with sexually transmitted infection (STI) transmission. Trends in these behaviors over the last decade, during which bacterial STI diagnoses have reached historic highs while HIV diagnoses have decreased, are not well understood. We examined recent trends in oral and anal sex and associated condom use with opposite-sex partners among females and males.

METHODS

We analyzed data from 16,926 female and 13,533 male respondents aged 15 to 44 years who reported sex with an opposite-sex partner in the past 12 months from the National Survey of Family Growth, 2011-2019. We used survey-weighted linear or logistic regression to evaluate linear temporal trends in oral and anal sex behaviors.

RESULTS

From 2011-2013 to 2017-2019, reports of oral sex and number of oral sex partners in the past 12 months increased among females (85.4% in 2011-2013 to 89.4% in 2017-2019; odds ratio [OR], 1.05 [95% confidence interval {CI}, 1.02-1.09], and β = 0.014 [95% CI, 0.005-0.023]; respectively) but not males (ranges, 87.9%-89.1%; 1.27-1.31). Condom use at last oral sex decreased among both females and males (6.3%-4.3%: OR, 0.93 [95% CI, 0.88-0.99]; 5.9%-4.4%: OR, 0.95 [95% CI, 0.91-1.00]). Anal sex (ranges, 21.0%-23.3% [females] and 23.3%-24.6% [males]), number of anal sex partners (females, 0.22-0.25; males, 0.26-0.30), and condom use at last anal sex (females, 15.3%-18.2%; males, 27.0%-28.7%) remained stable.

CONCLUSIONS

The frequency of oral and anal sex with opposite-sex partners among U.S. 15- to 44-year-olds, paired with limited and-for oral sex-decreasing condom use, demonstrates the need to understand the role of these behaviors in increasing STI diagnosis rates and the potential role of extragenital screening and condoms in reducing STI transmission.

Ensuring equity with pre-clinical planning for chlamydia vaccines

Chlamydia trachomatis (Ct) remains the most common bacterial sexually transmitted pathogen worldwide, causing significant morbidity particularly among women, including pelvic inflammatory disease, ectopic pregnancy, and infertility. Several vaccines are advancing through pre-clinical and clinical development, and it is likely that one or more vaccines will progress into human efficacy trials soon. In this Perspective, we present a case for considering the challenges of Ct vaccine development through a lens of equity and justice. These challenges include the need to protect against multiple serovars, in both females and males, at multiple anatomic sites, and in resource poor areas of the world. We propose that early consideration of vaccine implementation by conducting community-engaged research will ensure that a scientifically sound chlamydia vaccine promotes equity, justice, and shared-gendered responsibility for STI prevention.

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

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

Changes in Sexual Behaviors with Opposite-Sex Partners and Sexually Transmitted Infection Outcomes Among Females and Males Ages 15-44 Years in the USA: National Survey of Family Growth, 2008-2019

Rates of reported gonorrhea and chlamydial infections have increased substantially over the past decade in the USA and disparities persist across age and race/ethnicity. We aimed to understand potential changes in sexual behaviors, sexual network attributes, and sexually transmitted infection (STI) screening that may be contributing to these trends. We analyzed data from 29,423 female and 24,605 male respondents ages 15-44 years from the National Survey of Family Growth, 2008-2019. We used survey-weighted linear or logistic regression to evaluate linear temporal trends in sexual behaviors with opposite-sex partners, network attributes, and STI testing, treatment, and diagnosis. Significant declines were observed in condom use at last vaginal sex, mean number of vaginal sex acts, proportion of condom-protected sex acts in the past 4 weeks, and racial/ethnic homophily with current partners among males and females from 2008-2010 through 2017-2019. Among males, mean number of female partners in the past 12 months and concurrency also declined, while the percent reporting ever having sex with another male increased. Past-year testing for chlamydia and any STI increased among females. Research is needed to understand how these changes interact and potentially contribute to increasing reported gonorrhea and chlamydia diagnoses and identify avenues for future intervention.

Genomic Analysis of MSM Rectal Chlamydia trachomatis Isolates Identifies Predicted Tissue-Tropic Lineages Generated by Intraspecies Lateral Gene Transfer-Mediated Evolution

Chlamydia trachomatis is an obligate intracellular bacterium that causes serious diseases in humans. Rectal infection and disease caused by this pathogen are important yet understudied aspects of C. trachomatis natural history. The University of Washington Chlamydia Repository has a large collection of male-rectal-sourced strains (MSM rectal strains) isolated in Seattle, USA and Lima, Peru. Initial characterization of strains collected over 30 years in both Seattle and Lima led to an association of serovars G and J with male rectal infections. Serovar D, E, and F strains were also collected from MSM patients. Genome sequence analysis of a subset of MSM rectal strains identified a clade of serovar G and J strains that had high overall genomic identity. A genome-wide association study was then used to identify genomic loci that were correlated with tissue tropism in a collection of serovar-matched male rectal and female cervical strains. The polymorphic membrane protein PmpE had the strongest correlation, and amino acid sequence alignments identified a set of PmpE variable regions (VRs) that were correlated with host or tissue tropism. Examination of the positions of VRs by the protein structure-predicting Alphafold2 algorithm demonstrated that the VRs were often present in predicted surface-exposed loops in both PmpE and PmpH protein structure. Collectively, these studies identify possible tropism-predictive loci for MSM rectal C. trachomatis infections and identify predicted surface-exposed variable regions of Pmp proteins that may function in MSM rectal versus cervical tropism differences.

Nanoparticle-Based Lateral Flow Biosensor Integrated With Loop-Mediated Isothermal Amplification for Rapid and Visual Identification of Chlamydia trachomatis for Point-of-Care Use

Chlamydial infection, caused by Chlamydia trachomatis, is the most common bacterial sexually transmitted infection and remains a major public health problem worldwide, particularly in underdeveloped regions. Developing a rapid and sensitive point-of-care (POC) testing for accurate screening of C. trachomatis infection is critical for earlier treatment to prevent transmission. In this study, a novel diagnostic assay, loop-mediated isothermal amplification integrated with gold nanoparticle-based lateral flow biosensor (LAMP-LFB), was devised and applied for diagnosis of C. trachomatis in clinical samples. A set of LAMP primers based on the ompA gene from 14 C. trachomatis serological variants (serovar A-K, L1, L2, L3) was successfully designed and used for the development of C. trachomatis-LAMP-LFB assay. The optimal reaction system can be performed at a constant temperature of 67°C for 35 min. The total assay process, including genomic DNA extraction (~15 min), LAMP reaction (35 min), and LFB readout (~2 min), could be finished within 60 min. The C. trachomatis-LAMP-LFB could detect down to 50 copies/ml, and the specificity was 100%, no cross-reactions with other pathogens were observed. Hence, our C. trachomatis-LAMP-LFB was a rapid, reliable, sensitive, cost-effective, and easy-to-operate assay, which could offer an attractive POC testing tool for chlamydial infection screening, especially in resource starvation settings.