Using Urine to Study Antibodies & Functional Cell-Mediated Immunity in the Context of Chlamydia Trachomatis (URSAFE-CT)

The goal of this observational study is to learn if we can identify immune biomarkers in first-void urine and vaginal brush samples in Chlamydia trachomatis (CT) positive adult women. Participants will self-collect a first-void urine sample, self-collect a vaginal brush, and a blood sample will be collected by a healthcare worker. Participants will complete a questionnaire.

Study Overview

• Status: Recruiting
• Conditions: Chlamydia Trachomatis Genital Infection
• Intervention / Treatment: Device: Sampling

Detailed Description

To date, clinician-collected blood samples are still the primary methods to monitor immune responses to genital tract infections. Replacing these samples with a specimen that is non-invasive and can be self-collected, such as the initial or first-void urine stream or vaginal brushes, could have important acceptance and feasibility advantages and could facilitate the logistics of clinical trials and future epidemiological or vaccine studies. Moreover, these local samples give more information on the immune response at the site of infection, in the genital tract. Initial results of experiments using first-void urine samples and cervicovaginal brushes for immune response monitoring are promising. However, no standardized method for the detection of (functional) Chlamydia trachomatis (CT)-specific immune responses is available to be used on first-void urine or vaginal samples. Therefore, the aim of this pilot study is to determine feasibility to detect mucosal immune responses in first-void urine and self-collected vaginal samples. Furthermore, we will compare local immune responses with systemic immunity.

The primary objectives of this study are:

• To explore the feasibility to detect (functional) CT-specific antibodies and CT-specific cellular immune responses in first-void urine or self-collected vaginal samples.
• To compare levels of total and CT-specific antibodies in first-void urine and serum.
• To compare mucosal and systemic CT-specific cellular immune responses in mucosal mononuclear cells derived from first-void urine or self-collected vaginal samples, and peripheral blood mononuclear cells (PBMCs).

A total of 73 female participants will be included in this trial. Women that can be included have to be positive for a Chlamydia trachomatis nuclear acid amplification test (NAAT) on a vaginal or FVU sample, and have not yet been treated with antibiotic therapy.

The study described is a low-interventional observational study. Participants will self-collect a first-void urine sample using a 20 mL Colli Pee® device (Novosanis), followed by a vaginal brush (Evalyn® brush, Rovers). Medical personnel at the study site will collect a blood sample (one serum tube and 2 heparin tubes). Furthermore, personal data is collected via a paper-based questionnaire.

• Study Type: Observational
• Enrollment (Estimated): 73

Contacts and Locations

• Study Contact: Name: Anne Van Caesbroeck; Phone Number: +32 476 01 48 43; Email: anne.vancaesbroeck@uantwerpen.be

Study Locations

• Belgium
  • Antwerp
    • Antwerp, Antwerp, Belgium, 2000
      • Recruiting
      • Violett Antwerp
      • Contact: Ward Bauwens, MD; Phone Number: +32 3 293 95 91; Email: info@violett.be

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

A total of 73 Chlamydia positive female participants will be included.

Description

Inclusion Criteria:

• Female
• Chlamydia trachomatis NAAT positive vaginal sample or first-void urine sample.
• Able to understand the information brochure and what the study is about.
• Willing to give informed consent to use their samples for details described in the study protocol.

Exclusion Criteria:

• Pregnancy (self-reported)
• Being positive for Human Immunodeficiency Virus (HIV)
• Women that underwent hysterectomy.
• Menstruation at the time of sample collection.
• Current use of antibiotics effective against Chlamydia trachomatis (doxycyline or azithromycine) or use of such antimicrobials in the past 14 days before participating in the study.
• Participating in another clinical trial at the same time of participating in this study.
• Having a history or current evidence of any condition or abnormality that might confound the results of the study or is not in the best interest of the individual to participate, in the opinion of the investigator.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Concentration of total and Chlamydia-specific immunoglobulins in first-void urine and serum samples	Concentration of total and Chlamydia-specific immunoglobulins in first-void urine and serum samples determined using ELISA-based assays and the correlation of antibody titers between both sample types.	Within 6 months after study completion
Number of Chlamydia-specific SFCs per million cells	Quantification of antigen-specific cells in cells isolated from first-void urine samples, vaginal brush samples and whole blood samples (PBMC) using ELISpot-based assays.	Within 6 months after study completion
Measurement of percentage and median fluorescence intensity (MFI) of immune cell subsets in blood, first-void urine and vaginal brush samples.	Measuring percentage and MFI of immune cell subsets using flow cytometry	Within 6 months after study completion.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
STI DNA status of first-void urine and vaginal brush samples.	Nuclear acid amplification test for the presence of DNA from different sexually transmitted infections (including Chlamydia, Mycoplasma genitalium, Mycoplasma hominis, Neisseria gonorrhea, Trichomonas vaginalis, Ureaplasma parvum, Ureaplasma urealyticum) to investigate Chlamydia clearance or persistent infection and determine coinfections.	Within 6 months after study completion.
Other biomarkers	To test other biomarkers to normalize immune biomarkers measured in primary outcomes (antibody or cellular immune responses), for example total IgG, IgG subclasses, total protein, total human DNA etc.	Within 6 months after study completion.

Collaborators and Investigators

• Sponsor: Universiteit Antwerpen
• Collaborators: Violett Antwerp

Study record dates

Study Major Dates

• Study Start (Actual): December 10, 2025
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: May 12, 2026
• First Submitted That Met QC Criteria: May 12, 2026
• First Posted (Actual): May 19, 2026

Study Record Updates

• Last Update Posted (Actual): May 19, 2026
• Last Update Submitted That Met QC Criteria: May 12, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Chlamydia; Mucosal immunity; first-void urine; Colli Pee
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Infections; Communicable Diseases; Sexually Transmitted Diseases; Bacterial Infections; Bacterial Infections and Mycoses; Gram-Negative Bacterial Infections; Chlamydiaceae Infections; Sexually Transmitted Diseases, Bacterial; Chlamydia Infections
• Other Study ID Numbers: B3002025000147

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No