Chlamydial Pgp3 Seropositivity and Population-Attributable Fraction Among Women With Tubal Factor Infertility.

BACKGROUND: Chlamydial infection is associated with tubal factor infertility (TFI); however, assessment of prior chlamydial infection and TFI is imperfect. We previously evaluated a combination of serological assays for association with TFI. We now describe the chlamydial contribution to TFI using a newer Chlamydia trachomatis Pgp3-enhanced serological (Pgp3) assay. METHODS: In our case-control study of women 19 to 42 years old with hysterosalpingogram-diagnosed TFI (cases) and non-TFI (controls) in 2 US infertility clinics, we assessed possible associations and effect modifiers between Pgp3 seropositivity and TFI using adjusted odds ratios with 95% confidence intervals (CIs) stratified by race. We then estimated the adjusted chlamydia population-attributable fraction with 95% CI of TFI. RESULTS: All Black (n = 107) and 618 of 620 non-Black women had Pgp3 results. Pgp3 seropositivity was 25.9% (95% CI, 19.3%-33.8%) for non-Black cases, 15.2% (95% CI, 12.3%-18.7%) for non-Black controls, 66.0% (95% CI, 51.7%-77.8%) for Black cases, and 71.7% (95% CI, 59.2%-81.5%) for Black controls. Among 476 non-Black women without endometriosis (n = 476), Pgp3 was associated with TFI (adjusted odds ratio, 2.6 [95% CI, 1.5-4.4]), adjusting for clinic, age, and income; chlamydia TFI-adjusted population-attributable fraction was 19.8% (95% CI, 7.7%-32.2%) in these women. Pgp3 positivity was not associated with TFI among non-Black women with endometriosis or among Black women (regardless of endometriosis). CONCLUSIONS: Among non-Black infertile women without endometriosis in these clinics, 20% of TFI was attributed to chlamydia. Better biomarkers are needed to estimate chlamydia TFI PAF, especially in Black women.

Host Genetic Risk Factors for Chlamydia trachomatis-Related Infertility in Women.

BACKGROUND: Chlamydia trachomatis (Ct) infection ascending to the upper genital tract can cause infertility. Direct association of genetic variants as contributors is challenging because infertility may not be diagnosed until years after infection. Investigating the intermediate trait of ascension bridges this gap. METHODS: We identified infertility genome-wide association study (GWAS) loci using deoxyribonucleic acid from Ct-seropositive cisgender women in a tubal factor infertility study and Ct-infected cisgender women from a longitudinal pelvic inflammatory disease cohort with known fertility status. Deoxyribonucleic acid and blood messenger ribonucleic acid from 2 additional female cohorts with active Ct infection and known endometrial infection status were used to investigate the impact of infertility single-nucleotide polymorphisms (SNPs) on Ct ascension. A statistical mediation test examined whether multiple infertility SNPs jointly influenced ascension risk by modulating expression of mediator genes. RESULTS: We identified 112 candidate infertility GWAS loci, and 31 associated with Ct ascension. The SNPs altered chlamydial ascension by modulating expression of 40 mediator genes. Mediator genes identified are involved in innate immune responses including type I interferon production, T-cell function, fibrosis, female reproductive tract health, and protein synthesis and degradation. CONCLUSIONS: We identified Ct-related infertility loci and their potential functional effects on Ct ascension.

What Can Serology Tell Us About the Burden of Infertility in Women Caused by Chlamydia?

Chlamydia trachomatis (CT) causes pelvic inflammatory disease, which may result in tubal factor infertility (TFI) in women. Serologic assays may be used to determine the proportion of women with and without TFI who have had previous CT infection and to generate estimates of infertility attributable to chlamydia. Unfortunately, most existing CT serologic assays are challenged by low sensitivity and, sometimes, specificity for prior CT infection; however, they are currently the only available tests available to detect prior CT infection. Modeling methods such as finite mixture modeling may be a useful adjunct to quantitative serologic data to obtain better estimates of CT-related infertility. In this article, we review CT serological assays, including the use of antigens preferentially expressed during upper genital tract infection, and suggest future research directions. These methodologic improvements, coupled with creation of new biomarkers for previous CT infection, should improve our understanding of chlamydia's contribution to female infertility.

Etiology and Diagnosis of Pelvic Inflammatory Disease: Looking Beyond Gonorrhea and Chlamydia.

Pelvic inflammatory disease (PID) is a clinical syndrome that has been associated with a wide range of potential causal pathogens. Three broad groups of organisms have been isolated from the genital tract of people with PID: sexually transmitted organisms such as Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, and Trichomonas vaginalis; bacterial vaginosis (BV)-associated species and genera such as Atopobium vaginae, Sneathia, and Megasphaera; and genera and species usually associated with the gastrointestinal or respiratory tracts such as Bacteroides, Escherichia coli, Streptococcus, or Haemophilus influenza. Although PID is often considered to be synonymous with gonorrhea or chlamydia, these pathogens are found in only one quarter to one third of people with PID, suggesting that broader screening and diagnostic and treatment strategies need to be considered to reduce the burden of PID and its associated sequelae.

Assessment and utility of 2 Chlamydia trachomatis Pgp3 serological assays for seroprevalence studies among women in the United States.

Two plasmid gene protein (Pgp3)-based serological assays, the Pgp3-ELISA and multiplex bead assay (Pgp3-MBA), were compared and used to estimate seropositivity of Chlamydia trachomatis (CT) among females 14 to 39 years old participating in the National Health and Nutrition Examination Survey between 2013-2016. Of the 2,201 specimens tested, 502 (29.5%, 95% CI 27.6-31.5) were positive using Pgp3-ELISA and 624 (28.4%, 95% CI 26.5-30.3) were positive using Pgp3-MBA. The overall agreement between the assays was 87.7%. Corresponding nucleic acid amplification test (NAAT) results were available for 1,725 specimens (from women 18-39 years old); of these, 42 (2.4%, 95% CI 1.8-3.3) were CT NAAT-positive. Most of the CT NAAT-positive specimens had corresponding positive serological assay results; 33 (78.6%, 95% CI 62.8-89.2) were Pgp3-ELISA-positive and 36 (85.7%, 95% CI 70.8-94.1) were Pgp3-MBA-positive. Although Pgp3-ELISA and Pgp3-MBA demonstrated equivalent performance in this study, an advantage of the Pgp3-MBA over Pgp3-ELISA is that it is well suited for high sample throughput applications.

High Plasmid Gene Protein 3 (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. Plasmid gene protein 3 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 (CI) were compared for women with chlamydial infection, self-reported PID, and infertility. RESULTS: Of 2339 women aged 18-39 years, 1725 (73.7%) had sera, and 1425 were sexually experienced. Overall, 104 women had high positive Pgp3Ab (5.4% [95% CI 4.0-7.0] of US women); 407 had lowpositive 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.

Tubal Factor Infertility, In Vitro Fertilization, and Racial Disparities: A Retrospective Cohort in Two US Clinics.

BACKGROUND: Nearly 14% of US women report any lifetime infertility which is associated with health care costs and psychosocial consequences. Tubal factor infertility (TFI) often occurs as a result of sexually transmitted diseases and subsequent pelvic inflammatory disease. We sought to evaluate for and describe potential racial disparities in TFI and in vitro fertilization (IVF) prevalence. METHODS: Records of women aged 19 to 42 years in our retrospective cohort from 2 US infertility clinics were reviewed. We calculated TFI prevalence, IVF initiation prevalence, and prevalence ratios (PRs), with 95% confidence intervals (CIs) for each estimate, overall and by race. RESULTS: Among 660 infertile women, 110 (16.7%; 95% CI, 13.8-19.5%) had TFI which was higher in Black compared with White women (30.3% [33/109] vs 13.9% [68/489]; PR, 2.2 [95% CI, 1.5-3.1]). For women with TFI, IVF was offered to similar proportions of women by race (51.5% [17/33] vs 52.9% [36/68] for Black vs White women); however, fewer Black than White women with TFI started IVF (6.7% [1/15] vs 31.0% [9/29]; PR, 0.2 [95% CI, 0-1.0]), although the difference was not statistically different. CONCLUSIONS: Tubal factor infertility prevalence was 2-fold higher among Black than White women seeking care for infertility. Among women with TFI, data suggested a lower likelihood of Black women starting IVF than White women. Improved sexually transmitted disease prevention and treatment might ameliorate disparities in TFI.