Multilocus sequence typing of <i>Treponema pallidum pallidum</i> in children with acquired syphilis by nonsexual contact.

<b>Background:</b> There are scarce data of <i>Treponema pallidum</i> subsp. <i>pallidum</i> (TPA) characterization in children with syphilis. Nonsexually acquired transmission (NSAT) of TPA is possible in infants through close contact. <b>Methods:</b> A descriptive study in five families with NSAT of syphilis was conducted. Polymerase chain reaction detection of TPA in pediatric index cases (n = 6) and their relatives (n = 44) were conducted followed by multilocus sequence typing (MLST). <b>Results:</b> TPA was detected in swab samples in 16 cases and 12 were characterized by MLST. Nichols lineage was identified in two of five families and SS14-lineage in three of five. In four families, MLST profiles linked index cases to relatives. <b>Conclusion:</b> This is the first report of TPA characterization in children infected by NSAT.