Systemic Infections

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Systemic Infections
2012-04-11 22:20:07

systemic infection bugs
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  1. Rickettsia
    • Like Chlamydia obligated intracellular parasite replicate in cytoplasm however invade endothelial cells causing vasculitis in many organs
    • Cause high fevers, rashes (vasculitis, thrombosis), bad headaches, confusion, vomiting
    • gram neg rod
    • spreads by arthropod vector
    • Weil-Felix reaction - cross-reacting Proteus vulgaris antigens (OX2,19, K) to help confirm rickettsial infection (negative in Coxiella infection)
    • Indirect Immunofluorescence assay (IFA)
    • Rx: doxycycline
  2. Rickettsia rickettsii
    • Rocky mountain spotted fever (EMERGENCY)
    • vector: dermacentor tick
    • reservoir: wild rodents, domestic animals (dogs)
    • Rash starts on hands and feet and migrate to trunk
    • Endemic to East Coast (North/south Carolina, tennessee and oklahoma)
  3. Rickettsia prowazekii
    • Epidemic typhus (trunk)
    • Vector: Human body louse
    • Reservoir: humans, squirrels
    • flu-like symptoms, maculopapular rash (first on trunk --> spread to extremities) spares the plams, soles and face
    • war, overcrowding, poverty, unsanitary conditions
  4. Rickettsia typhi
    • Endemic typhus
    • Vector: flea
    • reservoir: rats
    • flu-like symptoms, maculopapular rash (first on trunk --> spread to extremities) spares the plams, soles and face
    • less seviour then prowazekii
  5. Coxiella burnetii
    • Q fever
    • Endospore form
    • spores from tick feces and cattle placenta
    • spores are inhaled cause human disease (atypical pneumonia)
    • NO rash
    • growth and division must occur intracellularly using host's ATP
  6. Ehrlichia chaffeensis
    • Granulocytes w/ berry cluster organisms (morula)
    • Vector: tick
    • Reservoir: dogs, deer
    • infect leukocytes --> inhibition of phagosome lysosome fusion + multiplication in cytoplasmic vacuoles (Morula)
    • symptoms similar to rickettsia rickettsii but no rash
    • found in same area as Lyme disease and transmitted by same tick as Lyme....therefore, can cause co-infection (much higher fever)
    • Rx: doxycycline
  7. Yersinia pestis
    • flea bite (coagulated blood in flea's gut is injected into human skin)
    • Southwest desert (arizona, new mexico)- prairie dogs, chipmunks, rodents
    • gram - rod, bipolar stain (safety pin like), facultative intracellular pathogen, type III secretion system: YOP proteins, F1 protein on the capsule has antiphagocytic properties, V and W antigens
    • Bubonic plaque: flu-like symptoms. the bacteria invade the skin and are gobbled up by macrophages. Within week move to nearest LN, usually the inguinal node. nodes swell like eggs and become hot red and painful. Fever and headache set in. Septicemic plaque (black death): bacilli invade the bloodstream, liver, lungs, and other organs. Hemorrhages under the skin cause a blackish discoloration.
    • Pneumonic plaque: from bacteremia or inhalation: flu-like symptoms + cough, bloody sputum, dyspnea and cyanosis (rapid death due to septic shock)
    • Rx: streptomycin, gentamicin
  8. Francisella tularensis
    • gram - coccobacilli, requires cysteine, facultative intracellular pathogen (inhibition of phagosome-lysosome fusion)
    • Tularemia
    • Rabbits, ticks (dermacentor), deer fly
    • bioweapon
    • just 10 organisms can cause disease- most labs will not culture it; if cultured need cysteine glucose blood agar
    • Ulceroglandular tularemia: demarcated hole in the skin w/ a black base develops at the site of bite or contact. Fever and systemic symptoms and swollen, red and painful LN like bubonic plague develops. But bubonic plague doesn't have skin ulcer
    • Oculoglandular form: areas of eye contact
    • Pneumonic: usually people who work w/ rabbits
    • Typhoidal tularemia -Gastrointertinal: after eating infected rabbit
    • Rx: streptomycin or gentamicin
  9. Brucella melitensis (goats), abortus (abortions in cows), suis (pigs)
    • Brucellosis/ undulant fever
    • unpasteurized dairy
    • gram - coccobacilli, facultative intracellular pathogens
    • direct contact, inhalation, ingestion of unpasteurized dairy products
    • CA, Texas, Mexico
    • Biowarfare
    • Multiply in macrophages (inhibit phagosome-lysosome fusion) --> granulomas --> septicemia
    • Flu-like symptoms, night sweats (undulant fever); profuse sweating (head to toe), depression
    • Rx: doxycycline + rifampin for 6 weeks
  10. Leptospira interrogans
    • gram - spiral morphology, motile, tight terminal hooks (question mark-shaped)
    • Shed in urine of infected animals
    • most prevalent among surfers and in the tropics (Hawaii highest incidence)
    • flulike symptoms, jaundice and photophobia w/ conjunctivitis (red eyes)
    • Weil's disease (icterohemorrhagic leptospirosis): jaundice and azotemia from liver and kidney dysfunction, fever, mental status changes, hemorrhage and anemia
    • Rx: penicilin or doxycycline
  11. Borrelia burgdorferi
    • large gram - spiral morphology, motile (endoflagella)
    • mice and deer are imp to tick (Ixodes) life cycle. Northeastern US.
    • late spring/early summer months
    • Early localized stage (bull's eye): 10 days after the bite lasts 4 weeks: erythema chronicum migrans (outer border remains bright red, while the center will clear, turn blue or even necrosis), flulike illness and regional lymphadenopathy
    • Stage 2:disseminated infect: cardiac (AV block, myocarditis)and neurologic (nerve palsies) abnormalities
    • Stage 3: persistent infect: fluctuating arthritis (migratory) lasts more than a year. involve 1 or2 of the large peripheral joints.
    • ELISA or IFA then Western blot
    • Rx: doxycycline or ceftriaxone
  12. Borrelia recurrentis
    • large gram - Spiral, motile (endoflagella)
    • Recurrent fever due to variable surface antigens
    • Human body louse
    • high fever, headache, muscle pain
    • drenching sweats, fever and symptoms resolve after 3-6 days. the patient remains afebrile for about 8 days, but then relapses, developing similar features for another 3-6 days.
    • Rx: doxycycline or erthromycin
    • microscopy (during febrile period) giemsa or wright staining