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Salmonella typhi

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Topic updated on 04/19/16 7:36pm

Introduction
  • Classification
    • Bacteria
      • Gram-negative bacilli
        • The Enterics
          • facultative anaerobes
            • Enterobacteriaceae
              • non-lactose fermenting
              • Salmonella
                • S. typhi
  • Pathogenesis
    • transmission
      • fecal-oral
        • "food, fingers, feces, flies"
    • reservoir
      • humans only
      • no animal reservoir
    • molecular biology
      • Vi antigen
        • blocks antibody attack on O antigen
      • invades intestinal mucosa
        • replicates within macrophages
        • infection begins in ileocecal region
        • bacteria progress to mesenteric lymph nodes and blood
        • severe inflammation in Peyer's patches can result in hemorrhage and gut perforation
        • can remain in gallbladder chronically
        • less virulent than Shigella
      • motile
        • flagella allow heterogenous dissemination ("salmon swim")
Diseases
  • Typhoid fever   
    • fever, abdominal pain, diarrhea, headache
    • rose spots on abdomen
    • mimics appendicitis
    • chronic carrier state is possible
      • Typhoid Mary
  • "Salmonella typhi gives salmon-colored spots and does the salmon swim"
  • Risk factors
    • poor hand hygiene
    • poor sanitation
    • drinking non-potable water
    • travel to regions with underdeveloped infrastructure
Laboratory
  • Vi antigen can be detected with Widal test
  • Produces H2S gas
  • Non-lactose fermenting
Treatment
  • Drugs
    • fluoroquinolones
    • 3rd generation cephalosporins
  • Vaccine
    • 3 vaccines are available
      • attenuated oral
      • parenteral heat-killed
        • no longer used in U.S.
      • parenteral ViCPS polysaccharide capsular


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Qbank (1 Questions)

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(M1.MC.83) A 43-year-old Caucasian male spent the past month on a business trip in the Caribbean. Two weeks following his return, he began experiencing diarrhea, pain in his abdomen, and a headache. He presents to the hospital and is noted to be febrile with prominent rose-colored spots on his chest and abdomen. Following recovery, the patient may become a carrier of the bacteria with the bacteria heavily localized to the: Topic Review Topic

1. Gallbladder
2. Spleen
3. CD4 T-helper cells
4. Lungs
5. Sensory ganglia

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