A Phase 4 interventional study of azithromycin and doxycycline in Chlamydia Trachomatis Infection, Vaginal Infection and Anal Infection, sponsored by University Hospital, Bordeaux. Completed at 7 sites in France. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-01.
Sponsored by University Hospital, Bordeaux · Phase 4, Interventional, and Treatment
Chlamydia trachomatis is the most commonly reported bacterial sexually transmitted infection (STI), especially among young women. Up to 75% of C. trachomatis infected women are asymptomatic. If untreated, C. trachomatis infection can cause sequelae such as pelvic inflammatory disease, ectopic pregnancy and tubal factor infertility. C. trachomatis can also cause anorectal infections, which are typically asymptomatic. Among women with urogenital chlamydial infection, around 36-91% also had concurrent anorectal chlamydial. Notably, there was no association with anal intercourse in the studies that reported it. However, guidelines do not recommend routine anorectal testing, but restricted testing in people who are in high-risk groups, report anal sexual behavior, or have anal symptoms, i.e., on selective indications. This is in contrast to urogenital testing, which is a routine procedure in STI care services.
The anal transmission of C. trachomatis in women may occur by autoinoculation from the vagina due to the close proximity of the vagina and the anus. C. trachomatis could lead to a persistent infection in the lower gastrointestinal tract, suggesting the potential role of autoinoculation of cervical chlamydial infection from the rectal site. Such (repeat) urogenital infections could lead to reproductive tract morbidity. Recommended treatments for C. trachomatis infections are a single 1g dose of azithromycin or 100mg of doxycycline 2 times a day for 7 days. Although these two regimens are equivalent for urogenital infection, no study has compared the effectiveness of these two treatments on anorectal infection. If rectal C. trachomatis is a hidden reservoir influencing transmission rates, and considering the potential complications of cervical infections, providing further evidence of the need for effective rectal treatments among women is highly relevant.
A possible reason for C. trachomatis detection after treatment may be transmission (self or another) or treatment failure. Whether antimicrobial treatment failure for C. trachomatis plays a role remains poorly understood. There is no evidence of antimicrobial resistance and testing for antimicrobial resistance for C. trachomatis is not routinely available. The hypothesis of transmission is most likely, especially as recontamination is very common among young people, either due to an untreated partner or a new partner. When these two conditions are ruled out, the hypothesis of autoinoculation from rectum to vagina is quite probable.
With regard to anorectal C. trachomatis infections, some studies concluded that azithromycin is a suboptimal treatment], while another study found doxycycline and azithromycin treatment to be equally effective. However, there are no robust studies that shows conclusive evidence relating to a suboptimal effect of any time of treatment or that prefers one treatment over the other.
The current study attempts to clarify the above question. The team propose to conduct the first open-label randomized controlled trial comparing the efficacy (measured as microbial cure) of a single 1g dose of azithromycin versus 100 mg of doxycycline twice daily for seven days for the treatment of anorectal C. trachomatis infection concurrent to urogenital infection in women. The experimental group will include women with C. trachomatis-positive vaginal and anorectal swabs treated with doxycycline twice daily for seven days with one tablet of 100 mg of doxycycline in the morning and evening. The control group will include women with C. trachomatis-positive vaginal and anorectal swabs treated with azithromycin consisting of four tablets of 250 mg of azithromycin in one intake.
The team made the hypothesis that the efficacy of azithromycin for anorectal infections may be lower than that of doxycycline, resulting in reinfections by autoinoculation from rectum to vagina. The expected result is that the number of women with a C. trachomatis-positive NAAT result in the anorectal swab will be significantly higher in the control group than in the experimental group after treatment.
98 studies on the registry are indexed under Vaginitis; 12 are open to participants now.
This study's enrollment of 460 is above the median of 108 across 71 interventional studies indexed under Vaginitis.
Browse Vaginitis studies →University Hospital, Bordeaux is the lead sponsor of 806 studies on the registry; 197 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The patients in the doxycycline group take one tablet of 100 mg twice a day for seven days. Antibiotics will be dispensed in their usual packaging with a clinical trial label.
Drug: doxycycline
The patients in the azithromycin group take 4 tablets of 250 mg in the morning as a single dose. Antibiotics will be dispensed in their usual packaging with a clinical trial label.
Drug: azithromycin
The route of administration is oral. It is administered at a dose of 1 g (4 tablets), as a single dose with or without food.
Also known as: Treatment
The patients in the doxycycline group take one tablet of 100 mg twice a day for seven days.
Also known as: Treatment
Nucleic Acid Amplification Assay result
C. trachomatis-positive NAAT result in anorectal specimens after treatment
Time frame: 6 weeks
the number of women with an anorectal C. trachomatis infection concomitant to a vaginal infection
The prevalence of anorectal C. trachomatis infection concomitant to a vaginal infection is the number of women with an anorectal C. trachomatis infection divided by the total number of women included in the study
Time frame: Day 1
C. trachomatis genotype
The number of subjects for whom the same C. trachomatis genotype profile will be identified in the vaginal-positive and anorectal-positive specimens obtained on the day of inclusion (self-infection), and in the anorectal-positive specimen obtained six weeks after treatment initiation (persistence) and in the vaginal-positive specimen obtained four months after treatment (autoinoculation).
Time frame: Day 1
C. trachomatis genotype
The number of subjects for whom the same C. trachomatis genotype profile will be identified in the vaginal-positive and anorectal-positive specimens obtained on the day of inclusion (self-infection), and in the anorectal-positive specimen obtained six weeks after treatment initiation (persistence) and in the vaginal-positive specimen obtained four months after treatment (autoinoculation).
Time frame: 6 weeks
C. trachomatis genotype
The number of subjects for whom the same C. trachomatis genotype profile will be identified in the vaginal-positive and anorectal-positive specimens obtained on the day of inclusion (self-infection), and in the anorectal-positive specimen obtained six weeks after treatment initiation (persistence) and in the vaginal-positive specimen obtained four months after treatment (autoinoculation).
Time frame: 4 months
Plan to share: No
This study is completed, as verified in Apr 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Doxycycline
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