GI: Diarrhea

Question 1

• Bloody Diarrhea
• Comma- or S-shaped organisms
• Growth at 42 Celcius

Answer 1

Campylobacter

Question 2

• Bloody Diarrhea
• Protozoan
• Amebid dysentery
• Liver abscess

Answer 2

E. Histolytica

Question 3

• Bloody Diarrhea
• O157:H7
• Hemolytic Uremic Syndrome (HUS)
• Shiga-like toxin
• Adheres to Colonic Epithelium but does not invade –> secretes Shiga-like toxin (SLT 1 and 2) –> Inflammation and Bleeding –> Dysentery (Hemorrhagic colitis)
• SLTs enter bloodsteam and can damage kidneys (HUS)

Answer 3

Enterohemorrhagic E. coli (EHEC)

Question 4

• Bloody Diarrhea
• Invades the Colonic mucosa
• Adheres to Colonic epithelium –> Invade mucosal layer and Secrete SLT 1 and SLT 2 –> Fever, Inflammation –> Bleeding –> Dysentery w/ Leukocytes in Stool (similar to shigellosis)

Answer 4

Enteroinvasive E. coli (EIEC)

Question 5

• Bloody Diarrhea
• Gram - rod cultured in Stool or Urine
• Lactose -
• Oxidase -
• Flagellar Motility
• Animal resrvoir (esp. Poultry and Eggs)
• Chicken / Turtles

Answer 5

Salmonella

Question 6

• Bloody Diarrhea
• Gram -
• Lactose - / non-fermentor
• Oxidase -
• Very low ID₅₀
• Shiga toxin producing –> Inactivates 60S Ribosome
• Hemolytic Uremic Syndrome (HUS)
• Human reservoir only
• Bacillary dysentery

Answer 6

Shigella dysenteriae

Question 7

• Bloody Diarrhea
• Day-care Outbreaks –> transmitted Raw-milk or Fecal-oral
• Pseudoappendicitis
• Localizes in Terminal Ileum –> secretes Heat-stable enterotoxin –> diarrhea
• Inflammation –> Colon Ulceration
• < 5 years –> Bloody diarrhea
• > 5 years –> Bloody diarrhea + Appendicitus-like Pain
• Adults –> Bloody diarrhea + Arthritis

Answer 7

Yersinia enterocolitica

Question 8

• Watery Diarrhea
• Pseudomembranous colitis (PMC)
• Caused by ABX
• Occasionally bloody diarrhea
• Toxin A –> alters fluid secretion –> watery diarrhea
• Toxin B –> Cytotoxic to Epithelial cells –> Pseudomembrane (Colonoscopy = Yellow-white plaques)(Toxin B presents in Feces)
• Gram + rod, strict anaerobe

Answer 8

Clostridium difficile

Question 9

• Watery Diarrhea
• Also causes Gas gangrene (Myonecrosis w/ Crepitus)
• Cellulitis
• Spores in Meat / Poultry foods –> survive cooking and Germinate –> Contaminated food ingested –> Bacteria release heat-liable enterotoxin in GI tract –> Enterotoxin inhibits glucose transport, damages epithelium –> diarrhea, gastric pain, nausea (No Fever, No Vomiting)
• Gram + rod, Strict Anaerobes, Nonmotile

Answer 9

Clostridium perfringens

Question 10

• Watery Diarrhea
• Travelers’ diarrhea
• Produces Heat-liable (LT) and Heat-stable (ST) toxins
  
  • LT - AB5 Toxin - activates adenylate cyclase –> increase cAMP –> Cl- and Na+ –> Osmotic water loss
  • ST - activates Guanylate cyclase –> increase cGMP
• -> decrease cotransport of NaCl into cells –> water remains in Lumen –> watery diarrhea
• Adhere to Jejunum, Ileum epithelium but do not invade

Answer 10

Enterotoxigenic E. coli (ETEC)

Question 11

• Watery Diarrhea
• Giardia
• Cryptosporidium (immunocompromised)

Answer 11

Protozoa

Question 12

• Watery Diarrhea
• Comma-shaped organisms
• “Rice-water” diarrhea
• Often from infected Seafood
• Dehydration
• Gram - bacilli
• Lactose non-fermenter
• Oxidase +
• Glucose fermenter

Answer 12

Vibrio Cholerae

Question 13

• Watery Diarrhea
• Rotavirus
  
  • Gastroenteritis
  • Vomiting followed by watery diarrhea
  • Nonenveloped DS segmented
• Norovirus
  
  • Gastroenteritis
  • Contaminated food / water w/ Local inflammation

Answer 13

Viruses