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.

Inclusion Criteria:

1. Infants at risk of congenital syphilis at birth defined as:

   1. 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

   2. 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).

2. Infants who are asymptomatic for a diagnosis of congenital syphilis following application of a clinical proforma by the study team (Appendix 1)

3. Infants who are less than <= 7 days of life AND with a post-menstrual age (PMA) of 34-42 weeks (Appendix 2).

4. 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.

2. They have a birthweight <2kg 3. They are nil by mouth. 4. They have a life-limiting congenital anomaly

At completion of the study an anonymised dataset will be deposited in an appropriate repository to facilitate sharing of IPD.

Following completion of the study

Data will be available via a repository to other researchers

It is not possible to blind the intervention to either participants or care providers given variation in route of administration and duration of therapy. Individuals assessing clinical and laboratory outcomes will be blinded to study group.