Internal Medicine - Infectious Diseases - Infectious Diarrhea

Question 1

What is the best initial test for diagnosis in a patient with diarrhea?

Answer 1

Test for blood and/or fecal leukocytes in stool.

Note: lactoferrin is a better answer than fecal leukocytes if it’s an option.

Question 2

What seven organisms commonly cause bloody diarrhea with WBCs in stool?

Answer 2

Salmonella
Campylobacter
E. coli
Shigella
Vibrio
Yersinia
Clostridium

Question 3

What five organisms commonly cause diarrhea with no blood and no WBCs in stool?

Answer 3

Viruses
Giardia
Cryptosporidium 
Bacillus
Staphylococcus

Question 4

Bloody diarrhea with history of consuming poultry?

Answer 4

Salmonella

Question 5

Bloody diarrhea with history of attending a picnic recently and presenting with signs of hemolysis?

Answer 5

E. coli 0157:H7 (most commonly)
OR
Shigella (second most common in US)

Question 6

Bloody diarrhea with history of shellfish consumption or travel in cruise ships?

Answer 6

Vibrio

Note: if history of liver disease or skin lesions, think Vibrio vulnificus specifically.

Question 7

Bloody diarrhea with history of hemochromatosis or multiple blood transfusions?

Answer 7

Yersinia (has a high affinity for iron!)

Question 8

Non-bloody diarrhea with history of camping/hiking and possibly drinking unfiltered fresh water? Treatment?

Answer 8

Giardia

Metronidazole (or tinidazole)

Question 9

Non-bloody diarrhea in a patient with history of HIV (CD4 count <100)? Treatment?

Answer 9

Cryptosporidiosis

Nitazoxanide (and treat underlying AIDS)

Question 10

Best method for confirming diagnosis of cryptosporidium-associated diarrhea?

Answer 10

Modified acid fast stain of stool

Question 11

Non-bloody diarrhea with vomiting? Treatment?

Answer 11

Bacillus cereus or Staphylococcus

Fluid support as needed

Question 12

Patient presents with sudden-onset wheezing, flushing, rash, and non-bloody diarrhea that began soon after eating fish at a seafood restaurant. What is the most likely diagnosis?

How would you treat this patient?

Answer 12

Scombroid

Antihistamines

Question 13

What are the six characteristics of “severe” infectious diarrhea?

Answer 13

Hypotension
Tachycardia
Fever
Abdominal pain
Blood in diarrhea
Metabolic acidosis

Question 14

How would you treat severe diarrhea?

How would you treat non-severe diarrhea?

Answer 14

Fluid replacement + oral antibiotics (ex: ciprofloxacin)

Oral fluid replacement