IDC Mycoplasma/Legionella

  1. What are the general characteristics of Rickettsiae?
    • Intracellular organisms
    • Very small (0.2-0.8 micro meters)
    • Grown in egg yolk or cell lines
    • Zoonoses humans accidental host
    • Infection transmitted by ticks
    • Short, non-motile G(=) bacilli
    • Not grown in cell-free media
    • Groups divided according to clinical infection: Spotted Fever, Typhus, Scrub typhus
  2. What are the Etiologic agent?
    • Rocky Mountain Spotted (Rickettsia rickettsii)
    • Typhus (Rickettsia prowazekii (murine)) and R. typhi louse borne)
    • Scrub typhus (Orientia tsutsugamushi)
  3. What are the Laboratory Diagnosis?
    • ID in refernce laboratories
    • Requires Level 3
    • Most labs do serology (latex, IF, Weil-Felix OX19, OX2, OXK)
    • Molecular techniques not standarizd
  4. What are the characteristics of Rocky Mountain Spotted fever?
    • Transmitted by Ticks
    • R. rickettsii
    • Organism first seen 1916
    • Humans accidental host
    • Disease acquired by tick bite
    • Live and replicate in host endothelial cells
    • Spread is hematogenous
  5. What are the Clinical Manifestations of Rocky Mt Spotted Fever?
    • Flu-like symptoms, incubation 7 days
    • Symptoms:fever, myalgia, headache
    • Rash begins in ankles and wrist, extending to palms and soles of feet
    • Once disseminated can cause vasculitis of blood vessels, lungs, breain heart
    • Mechanism not understood
    • Te or chloramphenicol
  6. What are the characteristics of the Typhus group?
    • R. typhi (endemic)
    • Replicate in cytoplasm
    • Cell lysis release all ricketts
    • Vector is a flea
    • Symptoms include fever, headache and rash occurs in trunk and extremities, if present, rarely on palms of hands
  7. Characteristics of The other typhus group:
    • Epidemic louse-borne typhus
    • R. prowasekii transmitted by louse
    • Reservoirs are primarily humans
    • The clinical course may resemble spotted fever, the rash may appear in hands and feet
    • Unlike spotted fever may involve the face
    • Untreated has a mortality rate 40%
    • Recrudescent typhus called Brill-Zinsser
  8. What are the characteristics of Scrub typhus?
    • Occurs in India, Burma, Russia, and Australia
    • Orientia tsutsugamushi transmitted by mites
    • Similar symptoms of rickettsia fever, headache and rash
    • Rash starts in the trunk and spreads to extremities does not involve palms and hands
  9. What are the characteristics of Enrlichia chafeensis?
    • Human monocytic ehrlichiosis
    • Obligate intracellular G(=) coco bacillus
    • Multiply in phagosomes of host WBC
    • Patient is febrile, leukopenic, thromocytopenic, and anemic
    • Only 20% patients have rashes (most common in pediatric patients)
  10. What are the S/S of Ehrlichia?
    • Neutropenia in acute phase, leukocytosis in later stages (not always) thrombocytopenia
    • Hypoproteinemia, hypoalbuminemia, and decreased sodium, potassium, chloride during the first 10 days
    • CPK and LDH often elevated in acute infection
    • Elevated ALT, AST, and AlkP
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IDC Mycoplasma/Legionella