Treponema pallidum - Syphilis

Treponema pallidum - Syphilis

 

Treponema pallidum subspecies pallidum is the causative agent of syphilis, a sexually transmitted infection (STI).

Epidemiology

  • Incidence
    • 2-5/100,000
    • Varies by region
  • Age
    • Peak age – teens to late twenties
  • Transmission    
    • Sexual contact
    • Maternal vertical transmission

Organism

  • Treponema pallidum subspecies pallidum is a member of the Spirochaetales family that causes syphilis and is distinct from endemic treponematoses of yaws (T. pallidum subspecies pertenue), pinta (T. pallidum subspecies carateum) and endemic syphilis (T. pallidum subspecies endemicum)
  • The Spirochaetales family also includes:
    • Leptospira species
    • Borrelia burgdorferi

Risk Factors for syphilis

  • Early aged onset of sexual activity
  • Multiple sex partners
  • Non-Caucasian
  • Infection with gonorrhea
  • Non-use of barrier methods
  • Previous history of STI
  • Infected with HIV

Clinical Presentation

  • Primary syphilis
    • Painless chancre at site of inoculation begins at about 3 weeks and may persist 4-6 weeks
  • Secondary syphilis
    • Two types
      • Latent and early latent <1 year
      • Late latent ≥1 year
    • Diffuse lymphadenopathy
    • Mucocutaneous lesions (condyloma lata)
    • Macular skin rash (palms and soles frequently)
    • Meningitis (rarely)
  • Tertiary (late) syphilis
    • 15-40% of untreated patients develop disease
    • Cardiovascular – aortitis
    • Gummatous syphilis – granulomatous, nodular lesions in organs (commonly skin and bones)
    • Neurologic – general paresis, tabes dorsalis
  • Congenital syphilis
    • Occurs during all stages of maternal syphilis
    • Typed according to age at diagnosis
      • Early (<2 years old, untreated)
        • Snuffles
        • Rash
        • Condyloma lata
        • Bone changes
        • Hepatosplenomegaly
        • Jaundice
        • Anemia
      • Late (>2 years, untreated)
        • 8th nerve deafness
        • Arthropathy (Clutton joints)
        • Neurosyphilis
        • Keratitis
      • Residual stigmata
        • Hutchinson’s teeth
        • Mulberry molars
        • Saddle nose
        • Saber shin
        • Rhagades scars
  • Central nervous system manifestations (may occur at any stage)
    • Symptomatic forms
      • Meningeal syphilis (usually <1 year after infection)
        • Involves the brain or spinal cord
        • Symptoms include headache, stiff neck
      • Meningovascular syphilis (usually 5-10 years after infection)
        • Inflammation of pia and arachnoid, with focal arteritis
        • Stroke syndrome involving middle cerebral artery is common in young adults
      • Parenchymatous (late syphilis)
        • General PARESIS (acronym for Personality, Affect; Reflexes, Eye (argyll Robertson pupil), Sensorium, Intellect, Speech)
        • Tabes Dorsalis – demyelination of posterior columns, dorsal roots and dorsal root ganglia
          • Characterized by wide-based gait and bladder symptoms
        • Charcot joints – trophic joint degeneration
        • Optic atrophy, frequently associated with tabes dorsalis (Argyll Robertson pupil)
    • May also be asymptomatic

Diagnosis

  • Laboratory testing
    • Culture not useful
    • Darkfield exam if chancre (primary) or condylomata lata (secondary) present
    • Nontreponemal tests
      • Rapid plasma reagin (RPR) – if reactive, order titers
      • VDRL may be used first but has higher false-positive rate
      • Use treponemal tests for confirmation or:
        • Fluorescent treponemal antibody absorption (FTA-Abs)
        • Microhemagglutination tests for antibodies to Treponema pallidum (MHA-TP)
        • IgM antibody detection by ELISA
    • Patient with newly diagnosed HIV should have syphilis testing, and patient with newly diagnosed syphilis should have HIV testing
    • Nontreponemal tests measure IgM and IgG antibodies
      • Positive titers are used to follow response to therapy for infected patients
    • Treponemal tests should not be used for screening purposes, given their higher false-positive rates (~1% in the general population) compared with non-treponemal tests
  • Diagnosis of neurosyphilis
    • In suspected cases, order VDRL on cerebrospinal fluid (CSF) and RPR from serum
    • If RPR is negative and a high index of suspicion for neurosyphilis remains, perform FTA-Abs from serum.  (Some patients have non-reactive non-treponemal tests in late neurosyphilis.)
    • Central nervous system (CNS) usually affected site in HIV patient
    • Follow treatment with repeat VDRL titers

Differential Diagnosis

  • Herpes simplex (primary syphilis)
  • Chancroid (primary syphilis)
  • Lymphogranuloma venereum (primary syphilis)
  • Behçet disease (primary syphilis)
  • Contact dermatosis (secondary syphilis)

Treatment

  • All stages of neurosyphilis require treatment to prevent disease progression and sequelae
  • Jarisch-Herxheimer reaction sometimes follows initial syphilis treatment
    • Fever/chills
    • Headache
    • Tachypnea
    • Tachycardia
    • Usually lasts <24 hours
    • Supportive care only
  • Treatment follow up:
    • Nontreponemal tests best for monitoring treatment or testing for reinfection (RPR for serum, VDRL for spinal fluid)
    • In CNS disease – CSF titers with VDRL should decrease
  • Intrauterine treatment <16 weeks into pregnancy prevents fetal damage

Click here for table of Comparisons of STI Screening Recommendations for Sexually Active Nonpregnant Women

Click here for table of Comparisons of STI Screening Recommendations for Pregnant Women


See Also