A Phase 2 interventional study of Linezolid (LZD) and Amoxicillin in Syphilis, Congenital, sponsored by London School of Hygiene and Tropical Medicine. Recruiting at 3 sites in 3 countries. Open to participants aged 0 Days to 7 Days. Per ClinicalTrials.gov, last updated 2026-10-22.
Sponsored by London School of Hygiene and Tropical Medicine · Phase 2, Interventional, and Treatment
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.
London School of Hygiene and Tropical Medicine is the lead sponsor of 298 studies on the registry; 15 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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.
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
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).
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.
2. They have a birthweight \<2kg 3. They are nil by mouth. 4. They have a life-limiting congenital anomaly
10 day course of Linezolid twice a day
Drug: Linezolid (LZD)
10 day course of Amoxicillin twice a day
Drug: Amoxicillin
Single IM dose of IM Benzathine penicillin
Drug: Benzathine Penicillin G
Ten day course. Oral Linezolid dosed at 10mg/kg twice a day.
Ten day course. Oral Amoxicillin dosed at 50mg/kg twice a day.
Single IM dose 50,000iu/kg
Time above MIC in serum
Time above MIC of T. pallidum for the dosing interval in serum
Time frame: From enrolment through to day 10 of the study
Time above MIC in CSF
Time above MIC in CSF throughout the dosing interval
Time frame: 10 days
Adverse Events
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.
Time frame: Assessed from enrolment through to 24 weeks
Clinical Outcome
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.
Time frame: Enrolment through to week 24
AUC/MIC Ratio in serum
Proportion of individuals achieving an AUC/MIC ratio ≥100 in serum
Time frame: Enrolment through to day 10
AUC/MIC Ratio in CSF
Proportion of individuals achieving an AUC/MIC ratio ≥100 in CSF
Time frame: Enrolment through to day 10
Plan to share: Yes — At completion of the study an anonymised dataset will be deposited in an appropriate repository to facilitate sharing of IPD.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Time frame: Following completion of the study
Access criteria: Data will be available via a repository to other researchers
No publications or documents are linked to this record.
Started May 2026 (actual). Primary completion is estimated for Mar 2027, 10 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drugs tested here: Linezolid · Amoxicillin
Syphilis, Congenital
London School of Hygiene and Tropical Medicine →