What are the clinical manifestations and treatment options for a newborn with congenital syphilis?

Clinical Manifestations and Treatment of Congenital Syphilis

Clinical Manifestations

Newborns with congenital syphilis present with a constellation of findings that include hepatosplenomegaly, jaundice, skin rash with desquamation (especially palms and soles), rhinitis, pseudoparalysis of extremities, nonimmune hydrops, and bone abnormalities. 1

Early Clinical Features

The most common presenting signs include:

• Low birth weight and prematurity - frequently observed in affected infants 2
• Hepatosplenomegaly - one of the most consistent findings, present in the majority of cases 1, 2, 3
• Skin manifestations - symmetrical superficial desquamation affecting palms and soles (62% in premature infants), syphilitic rash (54.9% of cases) 2, 4, 3
• Hematologic abnormalities - anemia is the most common laboratory finding (56.9% of cases) 2, 3
• Jaundice - frequently present with elevated transaminases and bilirubin 2, 4, 3
• Rhinitis - "snuffles" with nasal discharge that can be examined by darkfield microscopy 1
• Pseudoparalysis of extremities - due to painful osteochondritis 1

Skeletal Manifestations

Bone changes are present in 85% of cases and include periosteal reaction and metaphyseal dystrophy on long-bone radiographs. 4, 5 These skeletal findings can be the primary manifestation, particularly in premature infants. 5

Severe Presentations

• Nonimmune hydrops fetalis - should always raise suspicion for congenital syphilis when rhesus or ABO isoimmunization is excluded 2
• Stillbirth or neonatal death - can occur in untreated cases 6

Hepatic Involvement

When syphilitic hepatitis is present, expect:

• Elevated alanine aminotransferase and aspartate aminotransferase 3
• Elevated bilirubin with decreased albumin 3
• These markers significantly improve after appropriate penicillin treatment 3

Diagnostic Evaluation

Initial Assessment

All infants born to mothers with reactive serologic tests require quantitative nontreponemal testing (RPR or VDRL) performed on infant serum, NOT umbilical cord blood, as cord blood can be contaminated with maternal blood and yield false-positive results. 1, 7

Key Diagnostic Criteria

The diagnosis hinges on four factors:

1. Identification of maternal syphilis 1
2. Adequacy of maternal treatment 1
3. Clinical, laboratory, or radiographic evidence in the infant 1
4. Comparison of maternal and infant nontreponemal titers using the same test 1

Proven or Highly Probable Disease

Infants meet criteria for proven/highly probable disease with ANY of:

• Abnormal physical examination consistent with congenital syphilis 1
• Infant serum nontreponemal titer fourfold higher than maternal titer 1
• Positive darkfield examination of body fluids 1

Complete Evaluation for Proven/Probable Disease

Perform CSF analysis for VDRL, cell count, and protein - though interpretation is challenging as normal neonatal values can reach 25 WBCs/mm³ and protein of 150 mg/dL, with some specialists recommending lower thresholds (5 WBCs/mm³ and 40 mg/dL protein) 1

Additional required tests:

• Complete blood count with differential and platelet count 1
• Long-bone radiographs 1
• Chest radiograph 1
• Liver function tests 1
• Cranial ultrasound 1
• Ophthalmologic examination 1
• Auditory brainstem response 1

Important Testing Caveats

• Do NOT perform treponemal tests (TP-PA, FTA-ABS) on newborn serum - these are unnecessary as maternal IgG antibodies transfer transplacentally 1
• No commercially available IgM test is recommended 1
• Darkfield microscopy of suspicious lesions or nasal discharge should be performed when present 1
• Pathologic examination of placenta/umbilical cord with fluorescent antitreponemal antibody staining is suggested 1

Treatment

For Proven or Highly Probable Disease

Treat with aqueous crystalline penicillin G 100,000-150,000 units/kg/day IV, administered as 50,000 units/kg/dose every 12 hours during the first 7 days of life and every 8 hours thereafter for a total of 10 days. 1

Alternative regimen:

• Procaine penicillin G 50,000 units/kg/dose IM once daily for 10 days 1

Critical Treatment Principles

• If more than 1 day of therapy is missed, restart the entire 10-day course 1, 7
• Penicillin is the only proven effective treatment - data are insufficient for other antimicrobials like ampicillin 1, 8, 7
• When ampicillin was given initially for possible sepsis, complete the full 10-day penicillin course when possible 1
• Use of non-penicillin agents requires close serologic follow-up to assess treatment adequacy 1

For Infants with Inadequately Treated Mothers

Infants with normal examination and nontreponemal titer ≤ fourfold maternal titer, whose mothers received inadequate or no treatment, require a full 10-day course of parenteral penicillin therapy. 7

For Infants with Adequately Treated Mothers

If the mother received appropriate treatment during pregnancy and the infant has normal examination with titer ≤ fourfold maternal titer:

• Benzathine penicillin G 50,000 units/kg IM as a single dose 7

Treatment Beyond the Newborn Period

For children diagnosed with congenital syphilis after the newborn period, treat with aqueous crystalline penicillin G 200,000-300,000 units/kg/day IV or IM for 10-14 days. 8 CSF examination must be performed to exclude neurosyphilis in these cases. 8

Follow-Up

Perform serologic testing with nontreponemal tests every 2-3 months until tests become nonreactive or titers decrease fourfold. 8

• Do NOT use treponemal tests to evaluate treatment response - they remain positive despite effective therapy 8
• Nontreponemal titers should decline and eventually become nonreactive with successful treatment 8

Prevention Context

Routine prenatal screening at the first prenatal visit is essential, with repeat testing at 28 weeks gestation and delivery in high-risk populations. 8 No infant should leave the hospital without documented maternal serologic status. 1