What is the recommended treatment for a 2-month-old infant with suspected congenital syphilis?

Treatment of Congenital Syphilis in a 2-Month-Old Infant

Aqueous crystalline penicillin G 200,000-300,000 units/kg/day IV, administered as 50,000 units/kg every 4-6 hours for 10 days is the recommended treatment for a 2-month-old infant with suspected congenital syphilis. 1

Diagnostic Evaluation Before Treatment

Before initiating treatment, a comprehensive evaluation should be performed:

• CSF analysis for VDRL, cell count, and protein
• Complete blood count (CBC), differential, and platelet count
• Additional tests as clinically indicated:
  • Long-bone radiographs
  • Chest radiograph
  • Liver function tests
  • Abdominal ultrasound
  • Ophthalmologic examination
  • Auditory brain stem response
• HIV testing 1

Treatment Algorithm

1. First-line treatment: Aqueous crystalline penicillin G 200,000-300,000 units/kg/day IV, administered as 50,000 units/kg every 4-6 hours for 10 days 1

2. Alternative if IV access is problematic: Procaine penicillin G 50,000 units/kg IM daily in a single dose for 10 days 1

3. If more than 1 day of therapy is missed: The entire course should be restarted 1

4. After IV treatment completion: Some specialists suggest adding a single dose of benzathine penicillin G, 50,000 units/kg IM following the 10-day course of IV aqueous penicillin 1

Special Considerations

Penicillin Allergy

• Infants with history of penicillin allergy or who develop an allergic reaction should undergo desensitization and then be treated with penicillin 1
• No proven alternatives to penicillin exist for treating congenital syphilis 1
• If a non-penicillin agent must be used (extremely rare situation), close serologic and CSF follow-up are mandatory 1

Penicillin Shortage

During periods of penicillin shortage:

• Check local sources for aqueous crystalline penicillin G
• If limited, substitute some or all daily doses with procaine penicillin G
• Ceftriaxone (in age-appropriate doses) may be considered only if absolutely necessary, with careful clinical and serologic follow-up 1

Follow-Up Protocol

• Serologic testing (nontreponemal test) every 2-3 months until the test becomes nonreactive or the titer decreases fourfold 1
• Nontreponemal antibody titers should decline by 3 months of age and should be nonreactive by 6 months of age if adequately treated 1
• The serologic response may be slower for infants treated after the neonatal period 1
• If titers are stable or increase after 6-12 months of age, the child should be re-evaluated (including CSF examination) and retreated with a 10-day course of parenteral penicillin G 1

CSF Abnormalities

• Infants with abnormal initial CSF evaluations should undergo repeat lumbar puncture approximately every 6 months until results normalize 1
• A reactive CSF VDRL test or abnormal CSF indices that cannot be attributed to other ongoing illness requires retreatment for possible neurosyphilis 1

Important Caveats

• Treponemal tests should not be used to evaluate treatment response as they can remain positive despite effective therapy 1
• Passively transferred maternal treponemal antibodies can be present in an infant until age 15 months 1
• A reactive treponemal test after age 18 months is diagnostic of congenital syphilis 1
• If the nontreponemal test is nonreactive at 18 months, no further evaluation or treatment is necessary 1
• If the nontreponemal test is reactive at 18 months, the infant should be fully re-evaluated and treated for congenital syphilis 1

Despite recent research suggesting potential alternatives like ceftriaxone or amoxicillin 2, the evidence for these alternatives remains limited, and penicillin G remains the gold standard treatment to ensure optimal outcomes and prevent long-term complications of congenital syphilis.