12 Questions
Which of the following statements about Shigella is incorrect?
It is motile and produces hydrogen sulfide (H2S) on MacConkey agar.
What is the mechanism by which Shigella causes cellular invasion?
It induces M cells in Peyer's patches to phagocytose it, then escapes the phagolysosome.
What is the significance of Shigella being 'acid stable'?
It can survive in the acidic environment of the stomach.
Which of the following is a characteristic feature of Shigella dysentery (shigelosis)?
Bloody, inflammatory diarrhea with fever and tenesmus.
How does Shigella spread from cell to cell within the host?
By utilizing the host cell's actin cytoskeleton to propel itself.
Which of the following complications is most commonly associated with Shigella infection in children under 10 years of age?
Hemolytic uremic syndrome (HUS).
Which characteristic of Shigella is depicted by the 'Red Stool with flames surrounding it' in the text?
Produces bloody, inflammatory diarrhea
What does the 'Green Tutu' in the text represent about Shigella?
Shigella is indole positive, unlike Salmonella
What does the 'Chained to the weight' in the text indicate about Shigella?
Shigella is immotile and non-lactose fermenting
What is the significance of Shigella being 'acid stable' as mentioned in the text?
Shigella requires fewer organisms to cause infection
How does Shigella use the host cell's actin cytoskeleton as described in the text?
Shigella creates a tail to propel itself from one cell to another
What is the most common complication associated with Shigella infection in children under 10 years of age?
Hemolytic uremic syndrome (HUS)
Study Notes
Shigella Characteristics
- Gram-negative, enteric bacteria causing gastroenteritis
- Leads to watery diarrhea, followed by bloody diarrhea
Colony Characteristics
- Green colonies on Hektoen-enteric agar
- INDOLE POSITIVE, differentiating it from Salmonella, which grows black
Motility and Metabolism
- Immotile, non-lactose fermentation on MacConkey agar
- Non-H2S producing
Pathogenesis
- LPS (endotoxin) leads to inflammation and tissue damage
- Causes cellular membrane ruffling, leading to cell-to-cell passage
- Facultative intracellular, similar to Salmonella
Disease and Symptoms
- Causes Shigellosis, a severe form of enterocolitis
- Presents with fever, lower abdominal cramps, tenesmus, and bloody, inflammatory diarrhea
Complications
- Can lead to Hemolytic Uremic Syndrome (HUS) in children under 10 years old
Test your knowledge on Shigella, a Gram-negative enteric bacterium that causes gastroenteritis leading to watery and bloody diarrhea. Learn about its distinguishing features such as green colonies on Hektoen-enteric agar, indole positivity, and immotility.
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