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Treponema pallidum Overview

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Treponema pallidum overview

  • Characteristics
    • Spirochete
    • Technically gram negative
      • Too thin to be visualized on light microscopy
    • Motile
  • Transmission
    • Sexually transmitted
      • Frequent in MSM, HIV positive patients
      • Most commonly intimate contact with infectious lesion
      • Blood transfusion
      • Transplacentally from mother to fetus
      • Common in developing countries
  • Disease (syphilis
    • Primary syphilis
      • Painless chancre (ulcer on genitals)
        • Localized disease, occurs within 5 weeks from contact
        • Painless ulcer with raised, red borders
        • Heals within weeks without treatment
    • Secondary syphilis
      • Disseminated disease presenting 5-10 weeks after chancre resolution
      • condyloma lata
        • smooth, painless, wart-like white/grey lesions on genitals
      • maculopapular rash including palms and soles
        • Note: Palm and soles rash is also seen in Coxsackievirus and Rocky Mountain spotted fever
      • constitutional symptoms, lymphadenopathy, patchy hair loss also seen
    • Latent syphilis (+ serology without symptoms) may follow
    • Tertiary syphilis
      • Occurs many years after untreated infection
      • Gummas (chronic granulomas)
        • Painless, indurated granulomatous lesion that may ulcerate
        • Found in skin, bones, liver, heart (new murmur)
      • Aortitis/aortic aneurysm
        • Involvement and obliteration of vasa vasorum
          • blood vessels supplying thoracic aorta (not present in abdominal aorta)
        • Resulting  inflammation and ischemia weakens the aortic wall, causing aneurysm
      • Neurosyphilis
        • Can technically occur at any stage of syphilis, but more common in late-stage disease
        • Tabes Dorsalis
          • Occurs decades after initial infection with untreated syphilis
          • Posterior column of spinal cord impaired
            • Loss of proprioception and vibratory sense
            • Hyporeflexia
            • Stabbing nerve pain
            • Sensory ataxia
              • Broad-based gait
              • Inability to maintain balance with eyes closed (+ Romberg sign)
              • Charcot joint (joint damage due to neurodegeneration)
            • Loss of bladder function (neurogenic incontinence)
        • Argyll Robertson pupils
          • Constrict normally in accommodation (light-near-dissociation)
          • Fail to constrict in response to light (non-reactive)
          • Thought to result from damage to tectum of midbrain
        • Meningoencephalitis
          • Presents with headaches, dementia, or stroke
        • General paresis
          • Presents with progressive dementia and diffuse paralysis
  • Treatment
    •  Penicillin G
      • IM penicillin for primary or secondary syphilis and early latent syphilis
      • IV penicillin G for late latent syphilis 
      • Doxycycline as alternative for treating early and late latent syphilis
    • Treatment can cause Jarisch-Herxheimer reaction
      • Flu-like syndrome (fever, chills, headache, myalgia) after antibiotics are started
        • due to killed bacteria releasing gram-negative endotoxin