Practice questions 2 Infectious gastroenteritis

Practice questions 2

Infectious gastroenteritis

©Jun Wang, MD, PhD

 
1. Use this case and image for next 2 questions. A 41-year-old man presents to the emergency department with vomiting, diarrhea, and leg cramps for a day. He recently returned from a trip to a developing area and consumed seafood from street vendors. He appears critically ill and sluggish in communicating. His blood pressure is 85/55 mmHg, heart rate is 140 beats per minute. His eyes are sunken, and his skin and oral mucosa are dry. Laboratory tests reveal a hematocrit of 60% (normal 40-54%) and a serum bicarbonate level of 18 mmol/L (normal range: 22-28 mmol/L). An image of his stool is shown. What is the most likely pathogen?
 

(Image credit: F1jmm, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons)

A. Campylobacter jejuni
B. Entamoeba histolytica
C. Enterotoxigenic E. coli
D. Giardia intestinalis
E. Shigella
F. Vibrio Cholerae
 
2. A 41-year-old man presents to the emergency department with vomiting, diarrhea, and leg cramps for a day. He recently returned from a trip to a developing area and consumed seafood from street vendors. He appears critically ill and sluggish in communicating. His blood pressure is 85/55 mmHg, heart rate is 140 beats per minute. His eyes are sunken, and his skin and oral mucosa are dry. Laboratory tests reveal a hematocrit of 60% (normal 40-54%) and a serum bicarbonate level of 18 mmol/L (normal range: 22-28 mmol/L). An image of his stool is shown. What is the cause of his low blood pressure?

(Image credit: F1jmm, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons)
A. Abnormal dilatation of vessels
B. Diffuse microthrombi formation
C. Impaired right heart diastolic filling
D. Left ventricular dysfunction
E. Reduced circulating volume
 
 
3. Use this case for the next 4 questions. A 28-year-old female presents to the clinic with abdominal cramps and frequent, small-volume bloody stools for two days. She recently traveled to a developing country and consumed street food. Her past medical history is unremarkable. On examination, she appears acutely ill, with a temperature of 101.8°F (38.8°C). Abdominal examination reveals tenderness on palpation in the left lower quadrant. Initial stool microscopy shows abundant polymorphonuclear leukocytes and red blood cells. No cysts or trophozoites are seen. What test can be done for a fast diagnosis?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Molecular tests for enterotoxin LT
E. Multiplex molecular panels
F. Shiga toxin test

4. A 28-year-old female presents to the clinic with abdominal cramps and frequent, small-volume bloody stools for two days. She recently traveled to a developing country and consumed street food. Her past medical history is unremarkable. On examination, she appears acutely ill, with a temperature of 101.8°F (38.8°C). Abdominal examination reveals tenderness on palpation in the left lower quadrant. Initial stool microscopy shows abundant polymorphonuclear leukocytes and red blood cells. No cysts or trophozoites are seen.

Multiplex molecular tests reveal pathogen suspicious for Shigella or salmonella. What additional test should be done to confirm the diagnosis?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Shiga toxin test
E. Stool culture
 
5. A 28-year-old female presents to the clinic with abdominal cramps and frequent, small-volume bloody stools for two days. She recently traveled to a developing country and consumed street food. Her past medical history is unremarkable. On examination, she appears acutely ill, with a temperature of 101.8°F (38.8°C). Abdominal examination reveals tenderness on palpation in the left lower quadrant. Initial stool microscopy shows abundant polymorphonuclear leukocytes and red blood cells. No cysts or trophozoites are seen.
 
Stool culture at 37°C reveals Gram-negative, non lactose-fermenting bacilli that do not produce H₂S. How would this pathogen spread between colonic epithelium?
A. Cause host cell apoptosis and membrane damage
B. Direct invasion from apical surface
C. Form fibrin-rich deposits on the surface of epithelial cells
D. Promote formation of intracellular actin jet trail
E. Utilize flagellar motility
 
6. A 28-year-old female presents to the clinic with abdominal cramps and frequent, small-volume bloody stools for two days. She recently traveled to a developing country and consumed street food. Her past medical history is unremarkable. On examination, she appears acutely ill, with a temperature of 101.8°F (38.8°C). Abdominal examination reveals tenderness on palpation in the left lower quadrant. Initial stool microscopy shows abundant polymorphonuclear leukocytes and red blood cells.
 
Stool culture at 37°C reveals Gram-negative, non lactose-fermenting bacilli that do not produce H₂S. What is the pathogen?
A. Campylobacter jejuni
B. Entamoeba histolytica
C. Enterotoxigenic E. coli
D. Salmonella enterica
E. Shigella
F. Vibrio Cholerae
 
 
7. Use this case for the next 4 questions. A 35-year-old man presents to the clinic with abdominal cramps and non-bloody diarrhea for three days. He started having fever in the past 24 hours. Prior to these presentations, he ate a reheated chicken dish a few days ago. On examination, the patient is alert with mild stress. He has a temperature of 101.5°F. His other vital signs are within normal ranges. Physical examinations reveals mild abdominal tenderness. What test should be done to confirm the diagnosis?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Shiga toxin test
E. Stool culture
 
8. A 35-year-old man presents to the clinic with abdominal cramps and non-bloody diarrhea for three days. He started having fever in the past 24 hours. Prior to these presentations, he ate a reheated chicken dish a few days ago. On examination, the patient is alert with mild stress. He has a temperature of 101.5°F. His other vital signs are within normal ranges. Physical examinations reveals mild abdominal tenderness. What test should be done to confirm the diagnosis?
 
Stool culture at 37°C reveals Gram-negative, catalase-positive, oxidase-negative, bacilli that produce H₂S. What is most likely the pathogen?
A. Campylobacter jejuni
B. Entamoeba histolytica
C. Enterotoxigenic E. coli
D. Salmonella enterica
E. Shigella
F. Vibrio Cholerae
 
9. A 35-year-old man presents to the clinic with abdominal cramps and non-bloody diarrhea for three days. He started having fever in the past 24 hours. Prior to these presentations, he ate a reheated chicken dish a few days ago. On examination, the patient is alert with mild stress. He has a temperature of 101.5°F. His other vital signs are within normal ranges. Physical examinations reveals mild abdominal tenderness. What test should be done to confirm the diagnosis?
 
Stool culture at 37°C reveals Gram-negative, catalase-positive, oxidase-negative, bacilli that produce H₂S. Which part of the GI tract does this pathogen start invasion?
A. Cecum
B. Duodenum
C. Jejunum
D. Ileum
E. Colon
 
10. A 35-year-old man presents to the clinic with abdominal cramps and non-bloody diarrhea for three days. He started having fever in the past 24 hours. Prior to these presentations, he ate a reheated chicken dish a few days ago. On examination, the patient is alert with mild stress. He has a temperature of 101.5°F. His other vital signs are within normal ranges. Physical examinations reveals mild abdominal tenderness. What test should be done to confirm the diagnosis?
 
Stool culture at 37°C reveals Gram-negative, catalase-positive, oxidase-negative, bacilli that produce H₂S. What is the direct cause of his diarrhea?
A. Colonic vascular endothelial damage
B. Increased cAMP
C. Invasion of jejunal mucosa
D. Malabsorption
E. Suppression of normal colonic flora
 
 
11. Use this case for the next 4 questions. A 31-year-old woman presents to the emergency department with complaints of watery diarrhea, abdominal cramps, and low-grade fever for one days. Her stool is watery with a distinct foul odor. She was diagnosed with urinary tract infection a week ago and is taking oral antibiotics. Her significant past history include type 1 diabetes, Hashimoto thyroiditis, obesity and irregular uterine bleeding. She has a temperature of 100.5°F. Her other vital signs are within normal ranges. Abdominal examination reveals mild tenderness, but there is no rebound or guarding. What test should be done to confirm the diagnosis?
A. Clostridium difficile exotoxin tests
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Shiga toxin test
E. Stool culture
 
12. A 31-year-old woman presents to the emergency department with complaints of watery diarrhea, abdominal cramps, and low-grade fever for one days. Her stool is watery with a distinct foul odor. She was diagnosed with urinary tract infection a week ago and is taking oral antibiotics. Her significant past history include type 1 diabetes, Hashimoto thyroiditis, obesity and irregular uterine bleeding. She has a temperature of 100.5°F. Her other vital signs are within normal ranges. Abdominal examination reveals mild tenderness, but there is no rebound or guarding.
 
Her clostridium difficile exotoxin test is positive for toxin B, but negative for toxin A. What is the most likely pathogen?
A. Campylobacter jejuni
B. Clostridium difficile
C. Enterotoxigenic E. coli
D. Salmonella enterica
E. Shigella
F. Vibrio Cholerae
 
13. A 31-year-old woman presents to the emergency department with complaints of watery diarrhea, abdominal cramps, and low-grade fever for one days. Her stool is watery with a distinct foul odor. She was diagnosed with urinary tract infection a week ago and is taking oral antibiotics. Her significant past history include type 1 diabetes, Hashimoto thyroiditis, obesity and irregular uterine bleeding. She has a temperature of 100.5°F. Her other vital signs are within normal ranges. Abdominal examination reveals mild tenderness, but there is no rebound or guarding.
 
Her clostridium difficile exotoxin test is positive for toxin B, but negative for toxin A. What is the most likely cause of her diarrhea?
A. Activation of guanylate cyclase
B. Colonic mucosal injury
C. Increased cAMP
D. Invasion of jejunal mucosa
E. Malabsorption
 
14. A 31-year-old woman presents to the emergency department with complaints of watery diarrhea, abdominal cramps, and low-grade fever for one days. Her stool is watery with a distinct foul odor. She was diagnosed with urinary tract infection a week ago and is taking oral antibiotics. Her significant past history include type 1 diabetes, Hashimoto thyroiditis, obesity and irregular uterine bleeding. She has a temperature of 100.5°F. Her other vital signs are within normal ranges. Abdominal examination reveals mild tenderness, but there is no rebound or guarding.
 
Her clostridium difficile exotoxin tests is positive for toxin B, but negative for toxin A. What is the most significant risk factor for her diarrhea?
A. Antibiotics usage
B. Estrogen effects
C. Hypothyroidism
D. Overweight
E. Type 1 diabetes
 
 
15. Use this case and image for next 4 questions. A 25-year-old man presents to the clinic with progressively worsening abdominal pain and diarrhea for the past two weeks. He has loose stools containing visible blood. He returned from a trip to a tropical region before these symptoms. His past medical history is unremarkable. He appears fatigued and his vital signs are within normal ranges, except for a temperature of 100.5°F. There is tenderness over the lower abdomen without rebound or guarding. What laboratory tests should be performed to confirm the diagnosis?
A. Clostridium difficile exotoxin tests
B. Darkfield microscopic examination of stool
C. Regular light microscopic examination of stool
D. Shiga toxin test
E. Stool culture
 
16. A 25-year-old man presents to the clinic with progressively worsening abdominal pain and diarrhea for the past two weeks. He has loose stools containing visible blood. He returned from a trip to a tropical region before these symptoms. His past medical history is unremarkable. He appears fatigued and his vital signs are within normal ranges, except for a temperature of 100.5°F. There is tenderness over the lower abdomen without rebound or guarding.
 
An image of his stool microscopic exam is shown. What is the cause of his diarrhea?

(Image credit: The Other 95%, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons)
A. Activation of guanylate cyclase
B. Colonic mucosal injury
C. Increased cAMP
D. Invasion of jejunal mucosa
E. Malabsorption
 
17. A 25-year-old man presents to the clinic with progressively worsening abdominal pain and diarrhea for the past two weeks. He has loose stools containing visible blood. He returned from a trip to a tropical region before these symptoms. His past medical history is unremarkable. He appears fatigued and his vital signs are within normal ranges, except for a temperature of 100.5°F. There is tenderness over the lower abdomen without rebound or guarding.
 
An image of his stool microscopic exam is shown. What is most likely the source of his infection?

(Image credit: The Other 95%, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons)
A. Beef
B. Chicken
C. Rice
D. Seafood
E. Water
 
18. A 25-year-old man presents to the clinic with progressively worsening abdominal pain and diarrhea for the past two weeks. He has loose stools containing visible blood. He returned from a trip to a tropical region before these symptoms. His past medical history is unremarkable. He appears fatigued and his vital signs are within normal ranges, except for a temperature of 100.5°F. There is tenderness over the lower abdomen without rebound or guarding.
 
An image of his stool microscopic exam is shown. What is the pathogen?


(Image credit: The Other 95%, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons)
A. Entamoeba histolytica
B. Enterotoxigenic E. coli
C. Giardia intestinalis
D. Salmonella enterica
E. Shigella
F. Vibrio Cholerae
 
 
19. Use this case and image for next 4 questions. A 25-year-old woman presents to her primary care physician with diarrhea and abdominal discomfort for the past two weeks. She describes the diarrhea as foul-smelling, greasy, and accompanied by excessive gas. She went hiking and drank stream water in a remote area a month ago. Her vital signs are within normal ranges. On examination, she is well-nourished and alert. There is no evidence of dehydration. Abdominal examination reveals mild tenderness in the right upper quadrant. What test can be done for a quick diagnosis?
A. Clostridium difficile exotoxin tests
B. Darkfield microscopic examination of stool
C. Regular light microscopic examination of stool
D. Shiga toxin test
E. Stool culture
 
20. A 25-year-old woman presents to her primary care physician with diarrhea and abdominal discomfort for the past two weeks. She describes the diarrhea as foul-smelling, greasy, and accompanied by excessive gas. She went hiking and drank stream water in a remote area a month ago. Her vital signs are within normal ranges. On examination, she is well-nourished and alert. There is no evidence of dehydration. Abdominal examination reveals mild tenderness in the right upper quadrant.
 
Microscopic exam of her stool reveals finding similar to the image shown. What is the direct cause of her diarrhea?

(Image credit: Kalumet, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons)
A. Activation of guanylate cyclase
B. Colonic mucosal injury
C. Increased cAMP
D. Invasion of jejunal mucosa
E. Malabsorption
 
21. A 25-year-old woman presents to her primary care physician with diarrhea and abdominal discomfort for the past two weeks. She describes the diarrhea as foul-smelling, greasy, and accompanied by excessive gas. She went hiking and drank stream water in a remote area a month ago. Her vital signs are within normal ranges. On examination, she is well-nourished and alert. There is no evidence of dehydration. Abdominal examination reveals mild tenderness in the right upper quadrant.
 
Microscopic exam of her stool reveals finding similar to the image shown. What is the pathogen of her diarrhea?

(Image credit: Kalumet, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons)
A. Entamoeba histolytica
B. Enterotoxigenic E. coli
C. Giardia intestinalis
D. Salmonella enterica
E. Shigella
F. Vibrio Cholerae
 
 
 
Answers

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