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NCT Number: NCT06921213

Comprehensive Ambulatory Antibiotics for the Treatment of Congenital Syphilis

CARES-1 is a randomised, open-label, phase II pharmacokinetic (PK) and safety study of ambulatory antibiotics for the treatment of neonates with "all-risk" asymptomatic congenital syphilis.

Recruiting

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Key information

Age range

0 day–7 day

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

Universitas Indonesia, Jakarta, Indonesia

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Infants at risk of congenital syphilis at birth defined as:
  • an infant born to a mother who tests positive for syphilis in pregnancy using registered and licensed locally-available diagnostic tests for example but not limited to a Treponemal rapid POCT, an RPR or both.

AND

  • the mother is untreated in the current pregnancy defined as:

i. she tested positive at antenatal care and received no treatment OR ii. she was never tested during antenatal care OR iii. she tested negative at antenatal care and positive on re-testing at delivery

OR c. the mother is inadequately treated in the current pregnancy defined as:

i. Having received a non-penicillin based treatment regimen; and/or ii. Does not have documentation of 3 doses of IM Benzathine Penicillin, given 7-10 days apart, with the last dose given > 30 days prior to delivery OR b. The mother was adequately treated in the current pregnancy BUT considers herself at risk of re-infection following a midwife delivered explanation of risk (partner treatment, multiple partners etc).

  • Infants who are asymptomatic for a diagnosis of congenital syphilis following application of a clinical proforma by the study team (Appendix 1)
  • Infants who are less than <= 7 days of life AND with a post-menstrual age (PMA) of 34-42 weeks (Appendix 2).
  • Infants who are tolerating enteral feeds, including if they are being administered by an NG tube.

Exclusion criteria

  • 1. The infant's clinical condition at birth or prior to randomisation requires ongoing (> 48 hours) treatment with antibiotics with the potential for anti-treponemal activity i.e. B-lactams, Cephalosporins, Carbapenems.
  • They have a birthweight <2kg 3. They are nil by mouth. 4. They have a life-limiting congenital anomaly

Treatment and study plan

Linezolid (LZD)

Drug

Ten day course. Oral Linezolid dosed at 10mg/kg twice a day.

Amoxicillin

Drug

Ten day course. Oral Linezolid dosed at 50mg/kg twice a day.

Benzathine Penicillin G

Drug

Single IM dose 50,000iu/kg

Primary outcomes

  1. Time above MIC in serum

    Time frame: From enrolment through to day 10 of the study

    Time above MIC of T. pallidum for the dosing interval in serum

  2. Time above MIC in CSF

    Time frame: 10 days

    Time above MIC in CSF throughout the dosing interval

  3. Adverse Events

    Time frame: Assessed from enrolment through to 24 weeks

    The proportion of individuals experiencing an adverse event through to week 24. The trial will record SAE, SUSARS, and drug related AEs of grade 3 or higher.

Secondary outcomes

  1. Clinical Outcome

    Time frame: Enrolment through to week 24

    Proportion of infants who have clinical or laboratory evidence of congenital syphilis as adjudicated by an expert committee, blinded to treatment allocation, based on clinical and laboratory data.

  2. AUC/MIC Ratio in serum

    Time frame: Enrolment through to day 10

    Proportion of individuals achieving an AUC/MIC ratio ≥100 in serum

  3. AUC/MIC Ratio in CSF

    Time frame: Enrolment through to day 10

    Proportion of individuals achieving an AUC/MIC ratio ≥100 in CSF

Study contacts

Contact information is provided by the study sponsor or research team.

Sarah Prentice

CONTACT

[email protected]

+4420 7636 8636

Sponsors and collaborators

Lead sponsor

London School of Hygiene and Tropical Medicine

Other

Collaborators

  • MRC CTU at UCL
  • Malawi Liverpool Wellcome Programme
  • Murdoch Childrens Research Institute
  • PHPT/AMS Laboratory, Faculty of Associated Medical Sciences, Chiang Mai University
  • University College Dublin
  • University of Stellenbosch
  • University of Sydney

Registry information

Acronym: Cares-1

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Apr 10, 2025
Registry last updated
May 11, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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