USMLE

Rickettsia typhi vs. prowazekii

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Bacteria - Gram Negative
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  10. Salmonella Overview
  11. Salmonella typhi
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  25. Treponema pallidum: Diagnosis
  26. Congenital syphilis
  27. Chlamydia: Overview
  28. Chlamydia trachomatis
  29. Chlamydia pneumoniae vs. psittaci
  30. Rickettsia rickettsii
  31. Rickettsia typhi vs. prowazekii
  32. Anaplasma vs. Ehrlichia
  33. Coxiella burnetii (Q fever)

Rickettsia typhi + prowazekii 

  • R. prowazekii is a subtype of R. typhi
  • Characteristics
    • Gram negative
    • Obligate intracellular
  • Transmission
    • R. typhi vectors are usually fleas
      • Endemic, limited to areas where rats are common (rat fleas are implicated)
    • R. prowazekki vector is human body louse (lice)
      •  Epidemic - widespread due to human-to-human transmission
  • Presentation
    • Both species cause (murine) typhus
    • Nonspecific symptoms: fever, headache, myalgias
    • Rash spreads outwards
      • starts centrally on trunk and spreads to extremities
      • spares palms and soles
        • Contrast w Rickettsia rickettsii, which presents w/ rash on palms and soles
  • Diagnosis
    • Clinical, may be confirmed by indirect fluorescent assays
  • Treatment
    • Doxycycline
      • Caution during pregnancy; alternative is chloramphenicol