Alternative Antibiotics for Syphilis

  • End date
    Sep 24, 2023
  • participants needed
  • sponsor
    Fundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia
Updated on 24 November 2021


The Trep-AB clinical trial will test the efficacy of an investigational neuropenetrative drug, Linezolid (LZD), compared to standard treatment, Benzathine penicillin G (BPG), for early syphilis in humans. The overarching idea of the work proposed herein is to investigate the use of LZD to treat syphilis, conducting a randomized controlled clinical trial to evaluate this new indication of a known antibacterial agent. It is estimated to include 360 participants.


The syphilis epidemic is rampant around the world, and therapeutic options are restricted to an antibiotic, intramuscular (IM) BPG, which does not efficiently cross the blood-brain barrier. Treponema pallidum (T.p.), the bacteria that causes syphilis, invades the central nervous system (CNS) in 40% of patients, usually without symptoms. The prognostic implications of CNS invasion are the potential for severe neurologic complications, and treatment failure due to sequestered bacteria in the CNS. When indicated, the only way to identify and treat neurosyphilis is by lumbar puncture to examine the cerebrospinal fluid (CSF), followed by intravenous (IV) Benzyl penicillin therapy. The invetigators have carried out in silico studies showing that oxazolidinones are potentially active against T.p., are neuropenetrative and can be administered orally. The invetigators have carried out preclinical studies using an in vitro culture system for T.p. and the use of the syphilis animal model with rabbits to test different antibiotics. The invetigators have confirmed that LZD was the best compound that could go on to be tested in clinical trials to treat syphilis.

The Trep-AB clinical trial will test the efficacy of an investigational neuropenetrative drug, LZD, compared to standard treatment BPG, for early syphilis in humans conducting a randomized controlled clinical. Primary objective is to demonstrate the non-inferiority of LZD treatment compared with standard BPG treatment to cure patients with early syphilis. Seconday objective is to isolate T.p. strains in clinical samples to subtype DNA from patients at baseline and during recurrence or treatment failure. It is estimated to include 360 participants.

Condition secondary syphilis, early latent syphilis, Syphilitic chancre
Treatment linezolid, Benzathine Penicilllin G
Clinical Study IdentifierNCT05069974
SponsorFundación FLS de Lucha Contra el Sida, las Enfermedades Infecciosas y la Promoción de la Salud y la Ciencia
Last Modified on24 November 2021


Yes No Not Sure

Inclusion Criteria

Age 18 years or older at baseline visit
Primary, secondary or early latent syphilis diagnosis based on SEIMC/IUSTI Guidelines .a.Primary syphilis is defined as typical ulcer (chancre) and positive test using darkfield examination (DFE) or Polymerase chain reaction (PCR) detection of T.p. with/without positive serological test for syphilis
b.Secondary syphilis is defined based on typical clinical symptoms with
positive treponemal and non-treponemal tests
c.Early latent syphilis is defined as positive serological treponemal and non-
treponemal tests with no clinical evidence of infection, with a previous
negative syphilis serology,or a four-fold increase in RPR titer of a non-
treponemal test within the past 12 months.Serological tests for syphilis
performed within 10 days prior to study inclusion visit willbe acceptable for
\. Signature of written informed consent
\. Ability to comply with the requirements of the study protocol
\. If women of childbearing potential, use of a highly effective method of
contraception (abstinence,hormonal contraception, intra-uterine device [IUD]
or anatomical sterility in self or partner)committed during 1 week after last
IMP administration
\. If men, use of condom during heterosexual intercourse and use of a highly
effective method ofcontraception (abstinence, hormonal contraception, intra-
uterine device [IUD], or anatomical sterilityin self or partner) in female
partner committed during 1 week after last IMP administration
For inclusion purposes, positive point of care tests (POCT) will be accepted in selected patients without previous syphilis history and negative serological tests for syphilis during the last 12 months (Syphilis rapid diagnostic test [RDT] or Chembio DPP syphilis screen & confirm assay [DPP]), or with a previous history of syphilis and negative non-treponemal tests during the last 12 months (DPP). Further confirmation by the methods described in a), b) or c) will benecessary

Exclusion Criteria

Known allergy to any of the IMPs and/or excipients, particularly known hypersensitivity to penicillin, cephalosporins or other beta-lactam agents and/or allergy to soya or peanut
Lactose or galactose intolerance or glucose-galactose malabsorbtion
Diagnosis criteria of symptomatic neurosyphilis
Pregnant or breastfeeding women
Current treatment with any drugs likely to interact with the study medication (see Appendix 6)
Have taken any antibiotics with potential activity against syphilis (e.g. beta lactams, cephalosporines, macrolides, tetracyclines) within 1 week prior to randomization
Uncontrolled hypertension, pheochromocytoma, thyrotoxicosis, carcinoid syndrome, bipolar disorder, incapacitating psycho-affective disturbance, acute confusional state
Renal function impairment requiring hemodialysis
Symptomatic concomitant STI (i.e., gonococcus, chlamydia, lymphogranuloma venereum, Mycoplasma genitalium) or other infection disease requiring antibiotic treatment potentially active against syphilis
Having received treatment for the early syphilis recently diagnosed (In the previous 6 months)
Clear my responses

How to participate?

Step 1 Connect with a study center
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact



Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note