Linezolid for Syphilis Pilot Study

March 9, 2026 updated by: Jeffrey D Klausner, University of Southern California

Pilot Study of Linezolid for Early Syphilis Treatment

The study aims to evaluate the efficacy of linezolid for the treatment of syphilis.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This will be a randomized, open-label, non-comparative, pilot trial to evaluate the efficacy of linezolid 600mg orally, twice a day, for ten days, using a contemporaneous historical control group benzathine penicillin G (single dose of 2.4 million units) in participants with and without HIV infection.

In total, 24 participants will be enrolled across multiple clinical sites in the United States. Participants will participate in follow-ups to monitor clinical outcomes and serological response (RPR titer) at 1 month, 3 months, and 6 months. A 5 and 10-day phone call will ensure adherence to treatment and evaluate safety.

Study findings may identify an efficacious alternative syphilis treatment to penicillin that is effective for people living with HIV. Study findings may also help address the crisis of penicillin shortages, difficulty in administration, and offer options for those with penicillin allergy.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
24

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Illinois
      • Chicago, Illinois, United States, 60613
        • Howard Brown Health
    • Mississippi
      • Jackson, Mississippi, United States, 39216
        • University of Mississippi Medical Center
      • Jackson, Mississippi, United States, 39216
        • Open Arms HealthCare Center
    • North Carolina
      • Greensboro, North Carolina, United States, 27405
        • Wake Forest Baptist Health
    • Rhode Island
      • Providence, Rhode Island, United States, 02907
        • Open Door Health

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

16 years and older (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria: To be eligible for this study, participants must be:

  1. Diagnosed cases of primary, secondary or early latent syphilis with RPR titer ≥1:8 within 3 weeks prior to enrollment
  2. 16 years of age or older
  3. Able to provide informed consent/assent.
  4. Individuals with HIV infection must be on treatment for HIV-infection and virologically suppressed (viral load < 200 copies/mL) or have a CD4 count ≥ 350 cells/mm3 as of their most recent test prior to enrollment.

Exclusion Criteria include:

  1. Pregnancy or a positive pregnancy test on the day of enrollment
  2. Patients showing signs and symptoms of neurosyphilis.
  3. Participants who receive certain psychotropic medications, e.g., MAO inhibitors, SNRIs, SSRIs
  4. Serofast RPR titer, defined as persistently positive RPR titer without more than 4-fold (2-titer level) change for 12 months or greater.
  5. Recent (within the past 7 days) or concomitant antimicrobial therapy with activity against syphilis, namely azithromycin, tetracycline, doxycycline, cefixime, ceftriaxone or other beta lactam antibiotics (e.g. amoxicillin)
  6. Individuals with HIV infection who report HIV treatment interruption for more than 4 weeks since their most recent viral load or CD4 test.
  7. Individuals with known myelosuppressive conditions or receiving myelosuppressive medication
  8. Individuals weighing 150kg (330 lbs) or more.
  9. Individuals with known end renal stage disease, for example individuals in hemodialysis.
  10. Self-reported allergy to linezolid or penicillin.
  11. Unwilling or unable to attend follow-up visits.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Linezolid 10 Day
Oral linezolid 600mg, taken twice a day for 10 days
Drug: Group B, Linezolid 10d
Oral Linezolid 600mg, taken twice a day for 10 days
Other Names:
  • zyvox
Active Comparator: Benzathine Penicillin G
Single intramuscular injection of 2.4 million units of benzathine penicillin G
Drug: Group A, Penicillin
Standard of care benzathine penicillin G, one intramuscular injection, 2.4MU
Other Names:
  • bicillin

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Response to Treatment
Time Frame: 6 months
Percentage of linezolid participants with a 4-fold decrease or greater in the serum RPR titer by 180 days after treatment
6 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Treponema pallidum susceptibility
Time Frame: 6 months
Determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of linezolid against 6 historical and 3 clinical isolated strains
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Southern California

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
The University of Texas Health Science Center, Houston
Universidad Peruana Cayetano Heredia

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Jeffrey D Klausner, MD MPH, University of Southern California

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 28, 2023

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 16, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 16, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 21, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 9, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • APP-22-04165

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

No IPD will be shared with other researchers

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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