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Trial registered on ANZCTR


Registration number
ACTRN12622001340729
Ethics application status
Approved
Date submitted
12/10/2022
Date registered
18/10/2022
Date last updated
21/10/2022
Date data sharing statement initially provided
18/10/2022
Type of registration
Prospectively registered

Titles & IDs
Public title
Doxy Decay: The impact of doxycycline on the organism load and viability of urethral Mycoplasma genitalium and Chlamydia trachomatis
Scientific title
The impact of doxycycline 100mg PO twice daily for 7 days on the organism load and viability of urethral Mycoplasma genitalium and Chlamydia trachomatis
Secondary ID [1] 308173 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Urethral Mycoplasma genitalium 327894 0
Urethral Chlamydia trachomatis 327895 0
Nongonococcal urethritis 327896 0
Condition category
Condition code
Infection 324983 324983 0 0
Sexually transmitted infections

Intervention/exposure
Study type
Observational
Patient registry
False
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
This is a prospective observational study designed to determine the impact of doxycycline (100mg orally twice daily for 7 days) on urethral M. genitalium and C. trachomatis organism load and viability. Participants will be individuals with a known or suspected urethral M. genitalium and/or C. trachomatis infection who receive doxycycline as part of their standard treatment. Participants will be prescribed doxycycline 100mg twice daily for 7 days regardless of whether they choose to enrol in this study or not. Interested participants will be referred to the research team following their clinical consultation.

Participants will provide one urine sample prior to commencing doxycycline treatment (Day 0 sample). The Day 0 sample will be collected on the day of recruitment at Melbourne Sexual Health Centre. Participants will then be provided with a study kit and asked to self-collect one urine sample each day at home (Day 1 - Day 7) for the duration of their doxycycline treatment. A total of 8 urine samples will be collected by each participant.

Participants will be asked to complete a study diary each day (Day 0 -Day 7) for the duration of their doxycycline treatment outlining if and when they, a) took each dose of doxycycline and the approximate dose time, b) collected their urine sample and indicate time of collection. The diary will take approximately 2 minutes to complete.
Intervention code [1] 324622 0
Diagnosis / Prognosis
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 332785 0
Bacterial load of urethral M. genitalium over 7 days of doxycycline as measured by digital PCR using urine samples
Timepoint [1] 332785 0
Pre doxycycline dose (day 0), day 1, day 2, day 3, day 4, day 5, day 6 and day 7
Primary outcome [2] 332830 0
Bacterial load of urethral C. trachomatis over 7 days of doxycycline as measured by digital PCR using urine samples
Timepoint [2] 332830 0
Pre doxycycline dose (day 0), day 1, day 2, day 3, day 4, day 5, day 6 and day 7
Secondary outcome [1] 414707 0
Bacterial viability of urethral M. genitalium over 7 days of doxycycline as measured by the InSignia™ viability assay using urine samples
Timepoint [1] 414707 0
Pre doxycycline dose (day 0), day 1, day 2, day 3, day 4, day 5, day 6 and day 7
Secondary outcome [2] 414708 0
Change in male urethral microbiome composition (using urine samples) over 7 days of doxycycline as measured by 16S rRNA gene sequencing and/or shotgun metagenomic sequencing
Timepoint [2] 414708 0
Pre doxycycline dose (day 0), day 1, day 2, day 3, day 4, day 5, day 6 and day 7
Secondary outcome [3] 414709 0
Change in urethral microbiome composition (using urine samples) following 7 days of doxycycline among men with idiopathic urethritis as measured by 16S rRNA gene sequencing and/or shotgun metagenomic sequencing
Timepoint [3] 414709 0
Pre doxycycline dose (day 0), day 1, day 2, day 3, day 4, day 5, day 6 and day 7
Secondary outcome [4] 414813 0
Bacterial viability of urethral C. trachomatis over 7 days of doxycycline as measured by the InSignia™ viability assay using urine samples
Timepoint [4] 414813 0
Pre doxycycline dose (day 0), day 1, day 2, day 3, day 4, day 5, day 6 and day 7

Eligibility
Key inclusion criteria
Individuals attending Melbourne Sexual Health Centre (MSHC) will be eligible if they fulfil all the following criteria:
• Are prescribed doxycycline 100mg PO twice daily for 7 days for one of the indications below:
- men attending MSHC with NGU who receive presumptive doxycycline treatment, or
- men attending MSHC for doxycycline treatment (100mg PO twice daily for 7 days) for known or presumed/likely M. genitalium or C. trachomatis urethral infection, or
- men attending MSHC for a urethral M. genitalium test of cure with urethral symptoms and receive presumptive doxycycline treatment, or
- men attending MSHC as a sexual contact of M. genitalium or C. trachomatis with urethral symptoms in whom doxycycline is presumptively prescribed
• Are aged 18 years and older
• Are willing to participate in research
• Can understand and comply with study procedures
Minimum age
18 Years
Maximum age
No limit
Sex
Males
Can healthy volunteers participate?
No
Key exclusion criteria
Individuals will be ineligible if they fulfil any of the following criteria:
• Are currently taking or have been prescribed any antibiotics in addition to doxycycline on the day of enrolment.
• Are not fluent in English
• Are unwilling or unable to comply with study procedures

Study design
Purpose
Natural history
Duration
Longitudinal
Selection
Defined population
Timing
Prospective
Statistical methods / analysis
Sample size: Based on preliminary data, we anticipate that there will be a reduction in median M. genitalium load from 5 log10 copies/ml pre-treatment to 3.6 log10 copies/ml after 7 days of doxycycline. A sample size of 25 participants with a confirmed urethral M. genitalium infection will provide 90% power to detect this difference with a standard deviation of 2. As C. trachomatis infections have a higher organism load than M. genitalium infections and doxycycline effectively clears C. trachomatis infection, a sample size of 25 participants with a confirmed urethral C. trachomatis infection will provide adequate power to detect this difference. To account for 20% loss to follow-up, we will aim to recruit 32 participants with a confirmed urethral M. genitalium and 32 participants with a confirmed urethral C. trachomatis.

Men with nongonococcal urethritis (NGU) will be the principal recruitment source for this study, with recruitment supplemented by the other patient populations outlined in the inclusion criteria. We expect approximately 15% of men with NGU to have M. genitalium detected and 20% to have C. trachomatis detected. Therefore, we estimate will need to recruit 214 men with NGU to achieve a sample size of 32 participants with M. genitalium and 32 participants with C. trachomatis. Recruitment will stop when a sample size of 32 participants with M. genitalium and 32 participants with C. trachomatis is reached.

The primary analysis will be based on the bacterial load of M. genitalium and C. trachomatis over 7 days of doxycycline as measured by digital PCR. Digital PCR detects single molecules of target DNA which enables accurate quantification of organism load. To assess the bacterial load, the mean load of M. genitalium and C. trachomatis after each daily doxycycline dose will be calculated. Changes in bacterial load over time will be determined using linear mixed modelling.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
1/11/2022
Actual
Date of last participant enrolment
Anticipated
1/11/2023
Actual
Date of last data collection
Anticipated
8/11/2023
Actual
Sample size
Target
214
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 23366 0
Melbourne Sexual Health Centre (MSHC) - Carlton
Recruitment postcode(s) [1] 38747 0
3053 - Carlton

Funding & Sponsors
Funding source category [1] 312430 0
Government body
Name [1] 312430 0
Australian Research Council
Country [1] 312430 0
Australia
Primary sponsor type
University
Name
Monash University
Address
Level 1 Chancellery Building D
26 Sports Walk, Monash University,
Wellington Road, Clayton VIC 3800
Country
Australia
Secondary sponsor category [1] 314008 0
None
Name [1] 314008 0
Address [1] 314008 0
Country [1] 314008 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 311777 0
Alfred Hospital Ethics Committee
Ethics committee address [1] 311777 0
The Alfred
55 Commercial Rd,
Melbourne VIC 3004
Ethics committee country [1] 311777 0
Australia
Date submitted for ethics approval [1] 311777 0
22/08/2022
Approval date [1] 311777 0
18/10/2022
Ethics approval number [1] 311777 0
497/22

Summary
Brief summary
Mycoplasma genitalium and Chlamydia trachomatis are two of the most common sexually transmitted bacteria. Doxycycline is an antibiotic that is very effective for treating C. trachomatis and it is also used for M. genitalium. Doxycycline reduces the bacterial load of M. genitalium and can help to improve M. genitalium cure when taken before a second antibiotic. Current treatment guidelines recommend 7 days of doxycycline before starting the second antibiotic for M. genitalium. However, it is possible that taking the doxycycline for less than 7 days is just as effective. To determine if the duration of doxycycline treatment can be shortened without any impact of overall treatment efficacy, we need to understand how the amount and viability (if the bacteria is alive or dead) of M. genitalium and C. trachomatis changes each day during doxycycline treatment. Therefore, this study aims to determine the impact of doxycycline on the:
1. bacterial load of M. genitalium and C. trachomatis over 7 days in men attending a sexual health service
2. viability of M. genitalium and C. trachomatis over 7 days in men attending a sexual health service
3. urethral microbiota composition
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 122326 0
Prof Catriona Bradshaw
Address 122326 0
Melbourne Sexual Health Centre
580 Swanston Street
Carlton VIC 3053
Country 122326 0
Australia
Phone 122326 0
+61393416244
Fax 122326 0
Email 122326 0
catriona.bradshaw@monash.edu.au
Contact person for public queries
Name 122327 0
Dr Erica Plummer
Address 122327 0
Melbourne Sexual Health Centre
580 Swanston Street
Carlton VIC 3053
Country 122327 0
Australia
Phone 122327 0
+61393416258
Fax 122327 0
Email 122327 0
erica.plummer@monash.edu
Contact person for scientific queries
Name 122328 0
Dr Erica Plummer
Address 122328 0
Melbourne Sexual Health Centre
580 Swanston Street
Carlton VIC 3053
Country 122328 0
Australia
Phone 122328 0
+61393416258
Fax 122328 0
Email 122328 0
erica.plummer@monash.edu

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
Any sequencing data generated from this project will be made available
When will data be available (start and end dates)?
On completion of the study following publication. There is no end date for when data will be available.
Available to whom?
De-identified sequencing data will be uploaded in a public repository (e.g. Short Read Archive) accessible to anyone.
Available for what types of analyses?
Re-analysis of sequencing data
How or where can data be obtained?
De-identified sequencing data will be uploaded in a public repository (e.g. Short Read Archive) accessible to anyone.


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.