Seroprevalence of Chlamydia trachomatis Among Female Adults in the United States: The National Health and Nutrition Examination Surveys

Candidate antibody reference reagents for Chlamydia trachomatis serology

Chlamydia trachomatis (Ct) serology is an important tool for monitoring infection and disease burden but there are currently no formal reference reagents to harmonize results reporting. Our objective was to develop a panel of candidate reference reagents with reactivity against the major outer membrane protein (MOMP) and virulence factor (pgp3) antigens. Plasma packs from females (20-40 years old) were screened against MOMP and pgp3 antigens and selected positive and negative samples pooled to create a panel of candidate antibody reference reagents that were tested in two laboratories. Antigen specificity and internal quality assurance were also evaluated. Suitable candidate materials have been selected to produce Ct reference reagents.

Chlamydia trachomatis Seroassays Used in Epidemiologic Research: A Narrative Review and Practical Considerations

Chlamydia trachomatis (CT) is a sexually transmitted infection that can lead to adverse reproductive health outcomes. CT prevalence estimates are primarily derived from screening using nucleic acid amplification tests (NAATs). However, screening guidelines in the United States only include particular subpopulations, and NAATs only detect current infections. In contrast, seroassays identify past CT infections, which is important for understanding the public health impacts of CT, including pelvic inflammatory disease and tubal factor infertility. Older seroassays have been plagued by low sensitivity and specificity and have not been validated using a consistent reference measure, making it challenging to compare studies, define the epidemiology of CT, and determine the effectiveness of control programs. Newer seroassays have better performance characteristics. This narrative review summarizes the "state of the science" for CT seroassays that have been applied in epidemiologic studies and provides practical considerations for interpreting the literature and employing seroassays in future research.

The serodiagnositic value of Chlamydia trachomatis antigens in antibody detection using luciferase immunosorbent assay

Introduction

Among the different antigens used in the detection of anti-Chlamydia trachomatis antibodies, significant differences in sensitivity and specificity have been observed. Further evaluation of C. trachomatis antigens in antibody detection is urgently needed for the development and application of C. trachomatis serologic assays.

Methods

Chlamydia trachomatis antigens Pgp3, TmeA, InaC, and HSP60 were selected and used in luciferase immunosorbent assay (LISA). The detection results obtained from well-defined C. trachomatis positive and negative samples were compared with the commercial C. trachomatis ELISA (Mikrogen) for performance evaluation.

Results

Pgp3, TmeA, InaC, and HSP60-based LISA showed sensitivity of 92.8, 88.8, 90.4, and 94.4%, and specificity of 99.2, 99.2, 99.2, and 92%, respectively. ROC analysis indicated that Pgp3-based LISA showed similar performance to Mikrogen ELISA (AUC 0.986 vs. 0.993, p = 0.207). Furthermore, four C. trachomatis antigens achieved strong diagnostic efficiency, i.e., positive likelihood ratios [+LR] ≥ 10 in C. trachomatis-infected women and negative likelihood ratios [-LR] ≤ 0.1 in C. trachomatis negative low exposure risk children, but only Pgp3 and TmeA showed strong diagnostic value in general adults. In addition, Pgp3, TmeA, and InaC, but not HSP60, achieved high performance, i.e., both positive predictive value (PPV) and negative predictive value (NPV) ≥ 90.9%, and showed no significant cross-reactivity with anti-Chlamydiapneumoniae.

Conclusion

Three C. trachomatis species-specific antigens Pgp3, TmeA, and InaC show superior performance in the detection of anti-C. trachomatis antibody, indicating the potential to be used in developing C. trachomatis serologic tests.

Trends in Chlamydia trachomatis IgG seroprevalence in the general population of the Netherlands over 20 years

OBJECTIVES

To report sex and age-specific Chlamydia trachomatis (Ct) seroprevalence estimates in the general population of the Netherlands between 1996 and 2017 and identify risk factors associated with Ct seropositivity.

METHODS

Participants (n=5158, aged 15-59 years) were included from three independent nationwide population-based serosurveillance studies in 1996, 2007 and 2017. Participants completed a questionnaire on demographics and sexual behaviour. Serum antibodies were analysed using Medac Ct IgG ELISA test. Census weights were assigned to achieve seroprevalence estimates representative of the general Dutch population. Weighted seroprevalence estimates were stratified by gender, age and birth cohort. Trends and risk factors in men and women were identified using multivariable logistic regression.

RESULTS

Weighted overall Ct seroprevalence was 10.5% (95% CI: 9.2% to 12.0%) in women and 5.8% (95% CI: 4.7% to 7.0%) in men. Among women <25 years, there was a non-significant increase in seroprevalence from 5.9% (95% CI 3.7% to 9.2%) in 1996, to 7.6% (95% CI 5.1% to 11.1%) in 2007 and 8.8% (95% CI 5.5% to 13.9%) in 2017. Among women ≥25 years, the seroprevalence significantly decreased from 15.6% (95% CI: 12.2% to 19.7%) in 1996 to 9.5% (95% CI: 7.2% to 12.4%) in 2007 but did not further drop (11.2% (95% CI 8.1% to 15.3%) in 2017). In men, we did not observe trends between study rounds. In both men and women, having a non-Western migration background was a risk factor for seropositivity. In women, having had a prior sexually transmitted infection and ≥2 recent sex partners were risk factors for seropositivity as well.

CONCLUSIONS

We have not found evidence for a decrease in population seroprevalence in those under 25 years old despite decades of intensified testing-and-treatment efforts in the Netherlands. This suggests further monitoring of Ct burden in the general population is needed. If serum banks are used for this, specifically individuals <25 years old and with diverse migration backgrounds should be included.

Chlamydia trachomatis infection in Cuban adolescent and young populations

BACKGROUND

In Cuba, little is known regarding the prevalence of Chlamydia trachomatis (CT) infection in adolescents and young people. We study the frequency of CT infection in these populations, and its association with clinical-epidemiological variables.

METHODS

A total of 496 individuals aged 12 to 24 were recruited from November 2018 to November 2019. Of them, 302 were patients attending at sexually transmitted infections (STI) services and 194 were young volunteers. CT detections were carried out by real-time PCR and IgG serology.

RESULTS

The prevalence of CT using PCR was 9.1% (45/496); 12.3% (37/302) for subjects attending STI service and 4.1% (8/194) for young volunteers, being significantly higher in the first group (OR=3.25; p=.001). CT IgG antibodies was detected in 38.6% (81/210). Individuals from 12 to 17 years old were more likely infected with CT (OR=2.21; p=.010). Infection was associated with the early onset of sexual intercourse, the frequent changing of sexual partners and black ethnicity.

CONCLUSIONS

The results suggest that Cuban adolescents and young populations are at highest risk of acquiring CT infection and developing reproductive complications. The data obtained advise the needs of implementation of a routine CT screening strategy, for timely diagnosis, detection and treatment at the earliest ages.

Association between serum Chlamydia trachomatis antibody levels and infertility among reproductive-aged women in the U.S

Introduction

Chlamydia trachomatis infection, the most prevalent sexually transmitted bacterial infection worldwide, is a significant cause of infertility. Many countries have introduced the widespread use of serologic assays for IgG seropositivity to chlamydial plasmid gene product 3 (Pgp3). However, data on the association between the level of Pgp3-IgG in the multiplex bead array assay (Pgp3AbMBA) and female infertility are still scarce.

Methods

This cross-sectional analysis included 1,425 women from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016.

Results

In the fully adjusted logistic regression model, each standard deviation increments of Pgp3AbMBA (SD = 17,079.63) led to a 28% increase in the risk of infertility. The relationship remained consistent in women who had been pregnant and women who gave birth. Smooth curve fitting revealed that the association was linear across the entire range of Pgp3AbMBA. Subgroup analysis suggested that the association was significantly stronger in women who had ever used marijuana and lived in poverty.

Conclusions

This study revealed a linear and independent association between the level of Pgp3AbMBA and self-reported infertility in U.S. women. Furthermore, we found that women who had ever used marijuana and lived in poverty were at the highest risk of infertility upon chlamydial infection.

Exposure to Chlamydia trachomatis Infection in Individuals Who Are Newly Diagnosed with HIV and Antiretroviral-Naïve from Belém, Northern Brazil

Chlamydia trachomatis is one of the most prevalent sexually transmitted bacteria worldwide and may increase the risk of other sexually transmitted infections (STIs) including the human immunodeficiency virus (HIV). This study describes the seroprevalence of C. trachomatis infection among antiretroviral-naïve patients who are newly diagnosed with HIV in the city of Belém, Pará, in the Amazon region of Brazil. A cross-sectional study was carried out between January 2018 and January 2019 in 141 people living with HIV/AIDS (PLHA) who were followed up in a specialized unit of the public health network of Pará. The investigation of IgG antibodies against C. trachomatis was performed by enzyme immunoassay. Sociodemographic and sexual behavior information were obtained through a questionnaire. The prevalence of IgG anti-C. trachomatis antibodies was 64.8% (92/141). The majority of individuals were young, heterosexual, single men who did not use condoms during sexual intercourse and had no history of STIs. No significant differences were found when comparing any clinical or demographic data between groups. Our results demonstrated a high rate of exposure to C. trachomatis in newly diagnosed HIV-infected individuals in the Amazon region of Brazil, and all PLHA should be screened for C. trachomatis to decrease transmission of the bacteria and prevent the clinical manifestations of chronic infection.

Genital Chlamydia trachomatis Seroprevalence and Uterine Fibroid Development: Cohort Study of Young African-American Women

Few studies have investigated the 1930s hypothesis that reproductive tract infections are risk factors for fibroid development. In our 2017 cross-sectional analysis from the Study of Environment, Lifestyle, and Fibroids (2010–2018), a large Detroit community-based cohort of 23–35 year-old African-American women with ultrasound fibroid screening, we found an inverse association between seropositivity for genital Chlamydia trachomatis (gCT) infection and fibroids. With prospective data from the cohort (standardized ultrasounds every 20 months over 5 years), we examined gCT’s associations with fibroid incidence (among 1158 women fibroid-free at baseline) and growth. We computed adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for incidence by gCT serostatus using Cox proportional hazards models. GCT’s influence on growth was assessed by estimating the difference between fibroid size change for seropositive vs. seronegative between successive ultrasounds (1254 growth measures) using a linear mixed model. Growth was scaled to change over 18 months. GCT seropositivity was not associated with fibroid incidence (aHR, 1.0 95% CI: 0.79, 1.29) or growth (4.4%, 95% CI: −5.02, 14.64). The current evidence based on both biomarker gCT data, which can capture the common undiagnosed infections, and prospective ultrasound data for fibroids suggests that Chlamydia is unlikely to increase fibroid risk.

Seroepidemiology of Chlamydia trachomatis Infection in the General Population of Northern China: The Jidong Community Cohort Study

A longitudinal serological study to investigate the seropositive frequency, incidence, and antibody dynamics of Chlamydia trachomatis infection in the general population of China is urgently needed in order to optimize the strategies for surveillance and precise prevention of C. trachomatis infection. This longitudinal study enrolled 744 subjects aged 18-65 years from Jidong Community of Northern China from 2014 to 2018. Seropositive frequency, incidence, and reinfection of C. trachomatis were determined by detecting antibody against C. trachomatis Pgp3 using "in-house" luciferase immunosorbent assay (LISA). The dynamic of anti-Pgp3 antibody was analyzed using the Generalized Estimating Equation (GEE) model. The overall Pgp3 seropositive frequency among the 18-65-year-old population was 28.1% (95% CI 24.9-31.5), and significantly increased from 12.0% in those aged 18-29 years to 48.6% in the 60-65 years old. The seropositive frequency was slightly higher in women than in men (31.3% vs. 25.4%) without statistical significance. The C. trachomatis incidence and reinfection rate were 11 and 14 per 1,000 person-years, respectively, and showed no significant difference with respect to age, gender, ethnicity, marital status, and education levels. Furthermore, anti-Pgp3 antibody remained detectable in 93.3% (195/209) of the seropositive subjects during the 5 years of follow-up. The overall decay rate for anti-Pgp3 antibody for CT-infected persons was -0.123 Log2 RLU/year, which was dramatically slower than in CT new infection (-3.34 Log2 RLU/year) or reinfection (-1.1 Log2 RLU/year). In conclusion, at least one quarter of the people aged 18-65 years have been infected with C. trachomatis over their lifetime while all age groups are susceptible to C. trachomatis infection in the community of Northern China. Therefore, comprehensive prevention strategies are urgently needed.

High Pgp3 Chlamydia trachomatis seropositivity, pelvic inflammatory disease and infertility among women, National Health and Nutrition Examination Survey, United States, 2013-2016

BACKGROUND

Chlamydia trachomatis causes pelvic inflammatory disease (PID) and tubal infertility. Pgp3 antibody (Pgp3Ab) detects prior chlamydial infections. We evaluated for an association of high chlamydial seropositivity with sequelae using a Pgp3Ab multiplex bead array (Pgp3AbMBA).

METHODS

We performed chlamydia Pgp3AbMBA on sera from women 18-39 years old participating in the 2013-2016 National Health and Nutrition Examination Survey (NHANES) with urine chlamydia nucleic acid amplification test results. High chlamydial seropositivity was defined as a median fluorescence intensity (MFI ≥ 50,000; low-positive was MFI > 551-<50,000. Weighted US population high-positive, low-positive, and negative Pgp3Ab chlamydia seroprevalence and 95% confidence intervals (95% CI) were compared for women with chlamydial infection, self-reported PID, and infertility.

RESULTS

Of 2,339 women aged 18-39 years, 1,725 (73.7%) had sera and 1,425 were sexually experienced. Overall, 104 women had high positive Pgp3Ab (5.4% [95% CI 4.0-7.0] of US women); 407 had low positive Pgp3Ab (25.1% [95% CI 21.5-29.0]), and 914 had negative Pgp3Ab (69.5% [95% CI 65.5-73.4]).Among women with high Pgp3Ab, infertility prevalence was 2.0 (95% CI 1.1-3.7) times higher than among Pgp3Ab-negative women (19.6% [95% CI 10.5-31.7] versus 9.9% [95% CI 7.7-12.4]). For women with low Pgp3Ab, PID prevalence was 7.9% (95% CI 4.6-12.6) compared to 2.3% (95% CI 1.4-3.6) in negative Pgp3Ab.

CONCLUSIONS

High chlamydial Pgp3Ab seropositivity was associated with infertility although small sample size limited evaluation of an association of high seropositivity with PID. In infertile women, Pgp3Ab may be a marker of prior chlamydial infection.