What is the recommended workup and treatment for an infant born to a mother with syphilis?

Workup and Treatment for an Infant Born to a Mother with Syphilis

All infants born to mothers with syphilis require a thorough evaluation and possible treatment based on maternal history, physical examination findings, and laboratory results. 1

Initial Evaluation

Required for All Infants:

• Thorough physical examination for signs of congenital syphilis:
  • Nonimmune hydrops
  • Jaundice
  • Hepatosplenomegaly
  • Rhinitis
  • Skin rash
  • Pseudoparalysis of extremity 1
• Quantitative nontreponemal serologic test (RPR or VDRL) on infant serum (not cord blood) 1
• Comparison of infant's nontreponemal titer with mother's titer (using same test and preferably same laboratory) 1
• Pathologic examination of placenta/umbilical cord using fluorescent antitreponemal antibody staining 1
• Darkfield microscopy or direct fluorescent antibody staining of suspicious lesions or body fluids 1

Treatment Decision Algorithm

Scenario 1: Treat for Proven/Highly Probable Congenital Syphilis if:

• Abnormal physical examination consistent with congenital syphilis, OR
• Infant's nontreponemal titer is ≥4 times the maternal titer, OR
• Positive darkfield/fluorescent antibody test of body fluids 1

Additional Evaluation for Scenario 1:

• CSF analysis for VDRL, cell count, and protein
• Complete blood count with differential and platelet count
• Additional tests as indicated:
  • Long-bone radiographs
  • Chest radiograph
  • Liver function tests
  • Cranial ultrasound
  • Ophthalmologic examination
  • Auditory brainstem response 1

Treatment for Scenario 1:

• Aqueous crystalline penicillin G 100,000-150,000 units/kg/day IV, administered as 50,000 units/kg/dose every 12 hours during first 7 days of life and every 8 hours thereafter for a total of 10 days, OR
• Procaine penicillin G 50,000 units/kg/dose IM in a single daily dose for 10 days 1

Scenario 2: Treat if Normal Physical Exam and Nontreponemal Titer ≤4x Maternal Titer, but:

• Mother was not treated, inadequately treated, or has no documentation of treatment
• Mother was treated with erythromycin or non-penicillin regimen
• Mother received treatment <4 weeks before delivery
• Mother has early syphilis with inadequate serologic response (nontreponemal titer hasn't decreased fourfold or has increased) 1

Additional Evaluation for Scenario 2:

• CSF analysis for VDRL, cell count, and protein
• Complete blood count with differential and platelet count
• Long-bone radiographs 1

Treatment for Scenario 2:

Same as Scenario 1

Scenario 3: No Treatment Required if:

• Normal physical examination, AND
• Maternal treatment was adequate before pregnancy, AND
• Maternal nontreponemal titers remained low and stable during pregnancy and at delivery 2

Follow-up Recommendations

• For treated infants: Follow-up examinations and serologic testing at 3-month intervals until nontreponemal tests become nonreactive 1
• For untreated infants: Serologic testing every 2-3 months until test becomes nonreactive or titer decreases fourfold 2
• Nontreponemal antibody titers should decline by 3 months and become nonreactive by 6 months if infant was not infected 2

Important Caveats and Pitfalls

1. Do not use cord blood for testing - it may be contaminated with maternal blood and yield false-positive results 1

2. Treponemal tests are not useful in newborns - maternal IgG antibodies can persist in infant serum until 15 months of age 1, 2

3. False-negative results can occur - some infants with congenital syphilis may have negative serologic tests at birth if maternal infection occurred late in pregnancy 3

4. Late manifestations can develop - symptoms may first appear weeks after birth even with negative testing at delivery 3

5. Use the same test and laboratory for comparing maternal and infant titers to ensure accurate interpretation 1, 2

6. If treatment is interrupted (more than 1 day of therapy missed), the entire course should be restarted 1

7. Penicillin G is the only proven effective treatment - other antibiotics have not been proven effective and should not be used 1, 4

By following this structured approach to evaluation and treatment, congenital syphilis can be effectively diagnosed and managed, preventing serious long-term complications and mortality.