Practice questions 1 Infectious gastroenteritis

Practice questions 1

Infectious gastroenteritis

© Jun Wang, MD, PhD

 
1. Use this case for next 3 questions. A 19-year-old woman presents to the emergency department with mild to moderate mid-abdominal cramps, nausea, vomiting and watery diarrhea twice in the past 4 hours. She reports attending a social gathering the previous day at a local sea food restaurant. Her past medical history is unremarkable. She appears alert but a little bit tired. Her vital signs are within normal ranges. She has mild lower abdominal tenderness and hyperactive bowel sounds. No abdominal guarding is noted. Her stool is watery and negative for blood components. Other laboratory results are unremarkable. What is most likely the cause of her diarrhea?
A. Activation of guanylate cyclase
B. Efflux of Cl^– and H₂O
C. Invasion of jejunal mucosa
D. Malabsorption
E. Suppression of normal colonic flora
 
2. A 19-year-old woman presents to the emergency department with mild to moderate mid-abdominal cramps, nausea, vomiting and watery diarrhea twice in the past 4 hours. She reports attending a social gathering the previous day at a local sea food restaurant. Her past medical history is unremarkable. She appears alert but a little bit tired. Her vital signs are within normal ranges. She has mild lower abdominal tenderness and hyperactive bowel sounds. No abdominal guarding is noted. Her stool is watery and negative for blood components. Other laboratory results are unremarkable. What test be used for a quick identification of possible pathogens?
A. Colonoscopic examination and biopsy
B. Darkfield microscopic examination of stool
C. Multi-pathogen molecular tests
D. Regular microscopic examination of stool
E. Stool culture
 
3. A 19-year-old woman presents to the emergency department with mild to moderate mid-abdominal cramps, nausea, vomiting and watery diarrhea twice in the past 4 hours. She reports attending a social gathering the previous day at a local sea food restaurant. Her past medical history is unremarkable. She appears alert but a little bit tired. Her vital signs are within normal ranges. She has mild lower abdominal tenderness and hyperactive bowel sounds. No abdominal guarding is noted. Her stool is watery and negative for blood components. Other laboratory results are unremarkable. What pathogen is most likely the cause of her diarrhea?
A. Campylobacter
B. Clostridium difficile
C. Enterotoxigenic E. coli
D. Giardia intestinalis
E. Norovirus
F. Shigella
 
 
4. Use this case for the next 3 questions. A 21-year-old man presents with watery diarrhea for one day. He reports frequent, loose stools and mild abdominal cramps but does not have fever or vomiting. He recently returned from a five-day trip to a developing country and consumed street food, including raw vegetables and grilled meats. He is alert and has no signs of dehydration. Abdominal examination reveals mild tenderness in the lower abdomen and hyperactive bowel sounds. No guarding is noted. Stool exam reveals watery consistence without blood or excessive inflammatory cells. No cyst or trophozoites are seen. What is the most likely cause of his diarrhea?
A. Efflux of Cl^– and H₂O
B. Inhibition of guanylate cyclase
C. Invasion of jejunal mucosa
D. Malabsorption
E. Suppression of normal colonic flora
 
5. A 21-year-old man presents with watery diarrhea for one day. He reports frequent, loose stools and mild abdominal cramps but does not have fever or vomiting. He recently returned from a five-day trip to a developing country and consumed street food, including raw vegetables and grilled meats. He is alert and has no signs of dehydration. Abdominal examination reveals mild tenderness in the lower abdomen and hyperactive bowel sounds. No guarding is noted. Stool exam reveals watery consistence without blood or excessive inflammatory cells. No cyst or trophozoites are seen. What is the best way to confirm the diagnosis?
A. Colonoscopic examination and biopsy
B. Darkfield microscopic examination of stool
C. Molecular tests for enterotoxin LT
D. Regular microscopic examination of stool
E. Stool culture
 
6. A 21-year-old man presents with watery diarrhea for one day. He reports frequent, loose stools and mild abdominal cramps but does not have fever or vomiting. He recently returned from a five-day trip to a developing country and consumed street food, including raw vegetables and grilled meats. He is alert and has no signs of dehydration. Abdominal examination reveals mild tenderness in the lower abdomen and hyperactive bowel sounds. No guarding is noted. Stool exam reveals watery consistence without blood or excessive inflammatory cells. No cyst or trophozoites are seen. What is the most likely diagnosis?
A. Cholera
B. Enterotoxigenic Escherichia coli (ETEC) diarrhea
C. Norovirus gastroenteritis
D. Salmonella enterocolitis
E. Shigella dysentery
 
 
7. Use this case for the next 3 questions. A 32-year-old woman presents to the emergency department with a two-day history of fever, abdominal cramps and bloody diarrhea. She reports recent travel to a developing area in South America and consumed unpasteurized dairy products. On examination, she appears acutely-ill. She has a heart rate of 110 and a temperature of 101.5°F. Abdominal examination reveals diffuse tenderness, particularly in the left lower quadrant. Stool studies are positive for leukocytes and red blood cells, but no cysts or trophozoites are seen.  Multiplex molecular panels are positive for bacterial pathogens. What test should be performed next to confirm the cause of her presentations?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Molecular tests for enterotoxin LT
E. Stool culture
 
8. A 32-year-old woman presents to the emergency department with a two-day history of fever, abdominal cramps and bloody diarrhea. She reports recent travel to a developing area in South America and consumed unpasteurized dairy products. On examination, she appears acutely-ill. She has a heart rate of 110 and a temperature of 101.5°F. Abdominal examination reveals diffuse tenderness, particularly in the left lower quadrant. Stool studies are positive for leukocytes and red blood cells, but no cysts or trophozoites are seen.  Multiplex molecular panels are positive for bacterial pathogens.
 
Stool culture at 37°C reveals Gram-negative bacilli, forming dark pink colonies on sorbitol MacConkey agar. No Shiga toxin is detected. What is the most likely pathogen?
A. Clostridium difficile
B. Campylobacter
C. Enteroinvasive e coli
D. Enterohemorrhagic E coli
E. Shigella
F. Vibrio Cholerae
 
9. A 32-year-old woman presents to the emergency department with a two-day history of fever, abdominal cramps and bloody diarrhea. She reports recent travel to a developing area in South America and consumed unpasteurized dairy products. On examination, she appears acutely-ill. She has a heart rate of 110 and a temperature of 101.5°F. Abdominal examination reveals diffuse tenderness, particularly in the left lower quadrant. Stool studies are positive for leukocytes and red blood cells, but no cysts or trophozoites are seen.  Multiplex molecular panels are positive for bacterial pathogens.
 
Stool culture at 37°C reveals Gram-negative bacilli, forming dark pink colonies on sorbitol MacConkey agar. No Shiga toxin is detected. What is the most pathogenetic factor causing her diarrhea?
A. Activation of guanylate cyclase
B. Efflux of Cl^– and H₂O
C. Intestinal endothelial injury
D. Invasion of colonic mucosa
E. Malabsorption
 
 
10. Use this case for the next 4 questions. A 22-year-old woman presents to the emergency department with severe abdominal cramps and bloody diarrhea. Her abdominal cramps has been worsening for the last 24 hours. She had watery diarrhea 8 hours ago, which has now has blood in the stool. She denies history of recent travel, but she had consumed undercooked ground beef at a local restaurant three days ago. On examination, the patient appears dehydrated, and there is diffuse abdominal tenderness. Her CBC reveals a white cell count of 15 x 10³/μL (4.5-11 x 10³/μL) with slight left shift. Her hemoglobin and platelets are within normal ranges. Other laboratory tests results are unremarkable. What should be done next to confirm the diagnosis?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Molecular tests for enterotoxin LT
E. Stool culture
 
11. A 22-year-old woman presents to the emergency department with severe abdominal cramps and bloody diarrhea. Her abdominal cramps has been worsening for the last 24 hours. She had watery diarrhea 8 hours ago, which has now has blood in the stool. She denies history of recent travel, but she had consumed undercooked ground beef at a local restaurant three days ago. On examination, the patient appears dehydrated, and there is diffuse abdominal tenderness. Her CBC reveals a white cell count of 15 x 10³/μL (4.5-11 x 10³/μL) with slight left shift. Her hemoglobin and platelets are within normal ranges. Other laboratory tests results are unremarkable.
 
Stool culture at 37°C reveals Gram-negative bacilli forming white colonies on sorbitol MacConkey agar. What is most likely the pathogen?
A. Campylobacter jejuni
B. Enteroinvasive e coli
C. Enterohemorrhagic E coli
D. Enterotoxigenic E. coli
E. Shigella
F. Vibrio Cholerae
 
12. A 22-year-old woman presents to the emergency department with severe abdominal cramps and bloody diarrhea. Her abdominal cramps has been worsening for the last 24 hours. She had watery diarrhea 8 hours ago, which has now has blood in the stool. She denies history of recent travel, but she had consumed undercooked ground beef at a local restaurant three days ago. On examination, the patient appears dehydrated, and there is diffuse abdominal tenderness. Her CBC reveals a white cell count of 15 x 10³/μL (4.5-11 x 10³/μL) with slight left shift. Her hemoglobin and platelets are within normal ranges. Other laboratory tests results are unremarkable.
 
Stool culture at 37°C reveals Gram-negative bacilli forming white colonies on sorbitol MacConkey agar. What is most likely the cause of her diarrhea?
A. Activation of guanylate cyclase
B. Efflux of Cl^– and H₂O
C. Intestinal endothelial injury
D. Invasion of colonic mucosa
E. Malabsorption
 
13. A 22-year-old woman presents to the emergency department with severe abdominal cramps and bloody diarrhea. Her abdominal cramps has been worsening for the last 24 hours. She had watery diarrhea 8 hours ago, which has now has blood in the stool. She denies history of recent travel, but she had consumed undercooked ground beef at a local restaurant three days ago. On examination, the patient appears dehydrated, and there is diffuse abdominal tenderness. Her CBC reveals a white cell count of 15 x 10³/μL (4.5-11 x 10³/μL) with slight left shift. Her hemoglobin and platelets are within normal ranges. Other laboratory tests results are unremarkable.
 
Stool culture at 37°C reveals Gram-negative bacilli forming white colonies on sorbitol MacConkey agar. What additional test can be used to confirm the pathogen?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Molecular tests for enterotoxin LT
E. Shiga toxin test

 
14. Use this case for the next 4 questions. A 36-year-old woman presents to the primary care clinic with history of abdominal cramps, nausea, and diarrhea for three days. Her diarrhea started as watery and occasionally contain blood over the past 24 hours. She did not travel recently but consumed grilled chicken from a street vendor five days ago. She has a history including iron deficiency anemia, hypertension, autoimmune gastritis, Hashimoto thyroiditis and irregular uterine bleeding. Her vital signs are within normal ranges except for a temperature of 102°F. Physical examination reveals mild abdominal tenderness, but no signs of dehydration. Her CBC and other laboratory test results are within normal ranges. What additional test should be performed to confirm the diagnosis?
 
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Molecular tests for enterotoxin LT
E. Stool culture
 
15. A 24-year-old woman presents to the primary care clinic with history of abdominal cramps, nausea, and diarrhea for three days. Her diarrhea started as watery and occasionally contain blood over the past 24 hours. She did not travel recently but consumed grilled chicken from a street vendor five days ago. She has a history including iron deficiency anemia, hypertension, autoimmune gastritis, Hashimoto thyroiditis and irregular uterine bleeding. Her vital signs are within normal ranges except for a temperature of 102°F. Physical examination reveals mild abdominal tenderness, but no signs of dehydration. Her CBC and other laboratory test results are within normal ranges.
 
Stool culture on MacConkey agar at 37°C reveals no significant pathogens. However, stool culture on Skirrow agar at 42.0°C reveals colonies of Gram-negative curved rods. What is most likely the pathogen?
A. Campylobacter jejuni
B. Enteroinvasive e coli
C. Enterohemorrhagic E coli
D. Enterotoxigenic E. coli
E. Shigella
F. Vibrio Cholerae
 
16. A 24-year-old woman presents to the primary care clinic with history of abdominal cramps, nausea, and diarrhea for three days. Her diarrhea started as watery and occasionally contain blood over the past 24 hours. She did not travel recently but consumed grilled chicken from a street vendor five days ago. She has a history including iron deficiency anemia, hypertension, autoimmune gastritis, Hashimoto thyroiditis and irregular uterine bleeding. Her vital signs are within normal ranges except for a temperature of 102°F. Physical examination reveals mild abdominal tenderness, but no signs of dehydration. Her CBC and other laboratory test results are within normal ranges.
 
Stool culture on MacConkey agar at 37°C reveals no significant pathogens. However, stool culture on Skirrow agar at 42.0°C reveals colonies of Gram-negative curved rods. What is the major cause of her diarrhea?
A. Activation of guanylate cyclase
B. Efflux of Cl^– and H₂O
C. Inflammation of colonic mucosa
D. Intestinal endothelial injury
E. Malabsorption

17. A 24-year-old woman presents to the primary care clinic with history of abdominal cramps, nausea, and diarrhea for three days. Her diarrhea started as watery and occasionally contain blood over the past 24 hours. She did not travel recently but consumed grilled chicken from a street vendor five days ago. She has a history including iron deficiency anemia, hypertension, autoimmune gastritis, Hashimoto thyroiditis and irregular uterine bleeding. Her vital signs are within normal ranges except for a temperature of 102°F. Physical examination reveals mild abdominal tenderness, but no signs of dehydration. Her CBC and other laboratory test results are within normal ranges.
 
Stool culture on MacConkey agar at 37°C reveals no significant pathogens. However, stool culture on Skirrow agar at 42.0°C reveals colonies of Gram-negative curved rods. What is the risk for her diarrhea?
A. Autoimmune gastritis
B. Estrogen effects
C. Hypertension
D. Hypothyroidism
E. Iron deficiency anemia  

 
18. Use this case for the next 3 questions. A 35-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 is lethargic. His blood pressure is 90/60 mmHg, heart rate is 120 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). His stool is watery, milky, with abundant whitish mucus-like contents. What initial test can be done to confirm the diagnosis?
A. Clostridium difficile test
B. Colonoscopic examination and biopsy
C. Darkfield microscopic examination of stool
D. Molecular tests for enterotoxin LT
E. Shiga toxin test
 
19. A 35-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 is lethargic. His blood pressure is 90/60 mmHg, heart rate is 120 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). His stool is watery, milky, with abundant whitish mucus-like contents.
 
Darkfield microscopic examination of stool reveals numerous motile, comma-shaped organisms. What is the most likely pathogen?
A. Campylobacter jejuni
B. Entamoeba histolytica
C. Enterotoxigenic E. coli
D. Giardia intestinalis
E. Shigella
F. Vibrio Cholerae
 
20. A 35-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 is lethargic. His blood pressure is 90/60 mmHg, heart rate is 120 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). His stool is watery, milky, with abundant whitish mucus-like contents.
 
Darkfield microscopic examination of stool reveals numerous motile, comma-shaped organisms. What is the most likely cause of his diarrhea?
A. Activation of adenylate cyclase
B. Inflammation of colonic mucosa
C. Inhibition of ribosome function
D. Intestinal endothelial injury
E. Malabsorption

 

21. Use this case for the next 2 questions. A 6-year-old boy is brought to the emergency department with abdominal pain, bloody diarrhea and dark urine for two days. He consumed unpasteurized milk during a visit to a local farm a week ago. On examination, he appears pale and lethargic. He has a temperature of 100.5°F, a blood pressure of 135/80 mmHg, a heart rate of 135 bpm (normal 70-120 bpm), and a respiratory rate of 30 per minutes (normal 20-25). His CBC reveals a hemoglobin of 7.5 g/dL (11.5-13.5 g/dL), white cell count of 13.5 x 10⁹/L (5.3-11.5 x 10⁹/L) and platelet count of 110 x 10⁹/L (204-405 x 10⁹/L). Additional Laboratory tests reveal a BUN of 22 mg/dL (7-17 mg/dL), and a creatinine of 1.2 mg/dL (0.2-0.8 mg/dL). Peripheral blood smears reveals many fragmented red cells. Direct Coombs test is negative. What is most likely the cause of his diarrhea?
A. Campylobacter jejuni
B. Entamoeba histolytica
C. Enteroinvasive e coli
D. Enterohemorrhagic E coli
E. Salmonella enterica
F. Vibrio Cholerae

22. A 6-year-old boy is brought to the emergency department with abdominal pain, bloody diarrhea and dark urine for two days. He consumed unpasteurized milk during a visit to a local farm a week ago. On examination, he appears pale and lethargic. He has a temperature of 100.5°F, a blood pressure of 135/80 mmHg, a heart rate of 135 bpm (normal 70-120 bpm), and a respiratory rate of 30 per minutes (normal 20-25). His CBC reveals a hemoglobin of 7.5 g/dL (11.5-13.5 g/dL), white cell count of 13.5 x 10⁹/L (5.3-11.5 x 10⁹/L) and platelet count of 110 x 10⁹/L (204-405 x 10⁹/L). Additional Laboratory tests reveal a BUN of 22 mg/dL (7-17 mg/dL), and a creatinine of 1.2 mg/dL (0.2-0.8 mg/dL). Peripheral blood smears reveals many fragmented red cells. Direct Coombs test is negative. What is most likely the source of his infection? 
A. Chicken
B. Milk
C. Rice
D. Sea food
E. Water

 
 
Answers

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