This regimen is also recommended for infants with possible syphilis if the mother fits any of the following criteria: Untreated Treatment status unknown Treated ≤ 4 weeks before delivery Inadequately treated (a nonpenicillin regimen) Maternal evidence of relapse or reinfection (≥ 4-fold increase in maternal titer) In infants with possible syphilis whose mothers were not adequately treated but who are clinically well and have a completely negative full evaluation, a single dose of benzathine penicillin 50, 000 units / kg IM is an alternative treatment choice in selected circumstances but only if follow-up is ensured.