Lecture Notes: Salmonella (Andrew from Sketchy Micro)

Overview

• Discussing characteristics and differences between two subspecies of Salmonella:
  • Salmonella typhi
  • Salmonella enteritidis
• Using a visual sketch of a salmon dinner to illustrate features.

Shared Characteristics of Salmonella Subspecies

• Motility: Salmon tail flapping around
• H2S Positive: Grows black colonies on Hektoen agar plates
  • Represented by painting the plate black
• Encapsulation: Both are encapsulated
  • Illustrated by a glass dome over the salmon dish
• Acid Labile: Easily degraded in the stomach
  • High dose needed to cause infection
  • Conditions lowering stomach acidity increase susceptibility
  • Represented by a slice of lemon

Salmonella enteritidis

• Association: Under-cooked chicken
  • Represented by a chicken
  • Chicken as a main reservoir
• Clinical Feature: Causes inflammatory diarrhea
  • Represented by a candle flame (inflammatory)
• Pathogenic Factor: Type 3 secretion system
  • Represented by a turkey baster

Salmonella typhi

• Association: Gall bladder
  • Represented by a seagull (Gall bladder reservoir)
• Typhoid Mary: Historical carrier of typhoid fever
  • Seagull wears an apron with red spots
    • Rose spots in typhoid fever (25% of cases)
• Clinical Feature: Number one cause of osteomyelitis in sickle cell patients
  • Represented by exposed salmon bones
  • Seagull holding a sickle above the fish bones
• Diarrheal Description: Pea soup diarrhea (occasional)
  • Represented by bird droppings colored like pea soup
• Treatment: Responsive to antibiotics (fluoroquinolones)
  • Represented by a flower on the table
• Prevention: Live attenuated vaccine available
  • Represented by a syringe

Pathogenesis of Both Subtypes

• Facultative Intracellular: Capable of surviving within macrophages
  • Represented by bird cages with open doors

Final Review

• Salmon: Represents Salmonella
• Tail Flapping: Motile
• Black Plate: H2S positive
• Glass Dome: Encapsulated
• Lemon: Acid labile
• Chicken: Salmonella enteritidis (inflammatory diarrhea, type 3 secretion system)
• Seagull: Salmonella typhi (Gall bladder reservoir, Typhoid Mary, osteomyelitis in sickle cell, pea soup diarrhea, live attenuated vaccine, fluoroquinolones)
• Bird Cages: Facultative intracellular (macrophages)

Additional Resources

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• Access PDFs and sketches at website
• Feedback and suggestions welcome on YouTube