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Source: Knodel LC, Duhon B, Argamany J. Sexually transmitted diseases. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. Accessed March 9, 2017.


  • Sexually transmitted infection (STI)


  • Causative organism: Treponema pallidum, a spirochete.

  • Usually acquired by sexual contact with infected mucous membranes or cutaneous lesions.

    • On rare occasions can be acquired by nonsexual personal contact, accidental inoculation, or blood transfusion.


  • Organism penetrates intact mucous membrane or break in epithelium, resulting in spirochetemia.


  • Highly contagious infection that can progress to chronic, seriously disabling, or fatal, systemic disease.

  • Strong evidence of association between syphilis and HIV infection.

    • Centers for Disease Control and Prevention (CDC) recommends HIV testing in all patients diagnosed with syphilis.


  • Mutually monogamous sexual relationship between uninfected partners.

  • Barrier contraceptive methods.


  • Unprotected sex.

    • Risk of syphilis after unprotected sex with individual with infectious syphilis is ~50–60%.

  • Number of sexual partners.

  • Sexual preference.

  • Age.

    • Two-thirds of STIs occur in persons in teens and twenties.


  • Clinical presentation of syphilis varies, with progression through multiple stages possible in untreated or inadequately treat patients (Table 1).

  • Primary syphilis.

    • Characterized by appearance of chancre on cutaneous or mucocutaneous tissue.

    • Chancres persist only for 1–8 weeks before spontaneously disappearing.

  • Secondary syphilis.

    • Characterized by variety of mucocutaneous eruptions, resulting from widespread hematogenous and lymphatic spread of T. pallidum.

    • Lesions may be generalized or localized to a small portion of the body, and are mostly (except for follicular lesions) nonpruritic.

    • Signs and symptoms of secondary syphilis disappear in 4–10 weeks; however, in untreated patients, lesions may recur at any time within 4 years.

  • Latent syphilis.

    • Positive serologic test but no other evidence of disease.

    • Early latency (1 year from onset of infection, up to 2–4 years): patient is considered potentially infectious.

    • Late latency: mostly considered noninfectious, except in pregnancy, disease can pass from mother to fetus.

    • Most untreated patients with latent syphilis have no further sequelae.

      • ~25–30% progress to neurosyphilis or late syphilis with clinical manifestations other than neurosyphilis.

  • Tertiary syphilis and neurosyphilis.

    • If untreated, syphilis can produce an inflammatory reaction in any organ in the body.

    • Neurosyphilis: any patient with CSF abnormalities consistent with CNS infection (affects approximately 40% of patients with primary or secondary syphilis).


TABLE 1.Presentation of Syphilis Infections

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