A continuing challenge to determining the response to treatment of early syphilis (primary, secondary, early latent syphilis) is exemplified by the substantial proportion of patients who fail to achieve serological cure and remain serofast. Although retreatment is often done in clinical practice, optimal management remains uncertain due to the paucity of data regarding serological response to retreatment and long-term outcomes. Furthermore, the investigators cannot rule out that the gradually increasing seroreversion/serological cure rates may have been due to the natural decline in rapid plasma regain (RPR) titers after initial therapy, rather than due to the additional dose of benzathine penicillin. Thus, the investigators would like to conduct a clinical trial to compare the serological response rates of serofast early syphilis cases retreated with three doses benzathine penicillin and absence of any retreatment (control group).

Inclusion Criteria:

• Early Syphilis Cases Determined to Be Serofast at 6 Months after Initial Treatment

Exclusion Criteria:

• Human immunodeficiency virus (HIV)-infected
• Baseline serology showed a nonreactive RPR test
• follow-up is inadequate
• Allergic to penicillin
• Pregnant woman