A 3-year-old boy is brought to the emergency department because of abdominal pain and diarrhea for the past 3 days.. The stools were initially watery but have now become bloody. On physical examination, his temperature is 100.4 F (38 C). There are signs of dehydration and he has a mildly distended abdomen with diffuse pain elicited on palpation. Stool studies are positive for fecal leukocytes and occult blood. Fecal cultures grow non-lactose fermenting, gram-negative rods on MacConkey agar. The bacteria ferment glucose without gas production, do not generate hydrogen sulfide when grown on triple sugar iron agar, and cannot replicate at refrigeration temperatures. Which of the following bacterial factors is the most important during the pathogenesis of this patient's disease?

Question

A 3-year-old boy is brought to the emergency department because of abdominal pain and diarrhea for the past 3 days..  The stools were initially watery but have now become bloody.  On physical examination, his temperature is 100.4 F (38 C).  There are signs of dehydration and he has a mildly distended abdomen with diffuse pain elicited on palpation.  Stool studies are positive for fecal leukocytes and occult blood.  Fecal cultures grow non-lactose fermenting, gram-negative rods on MacConkey agar.  The bacteria ferment glucose without gas production, do not generate hydrogen sulfide when grown on triple sugar iron agar, and cannot replicate at refrigeration temperatures.  Which of the following bacterial factors is the most important during the pathogenesis of this patient's disease?

Quizplus · Accepted Answer

Eductional Objective: Shigella is a non-motile, non-lactose fermenting organism that does not produce H₂S when grown on triple sugar iron agar. Mucosal invasion of the M cells that overlie Peyer's patches is an essential pathogenic mechanism for Shigella infection. Shigella then escapes the phagosome and spreads laterally to other epithelial cells via actin polymerization.

A 3-Year-Old Boy Is Brought to the Emergency Department Because