Infections of the GI Tract

Question 1

What are some common bacterial infections of the GIT?

Answer 1

Salmonella
Campylobacter
Shigella
EHEC
C. difficile

Question 2

What are some common protozoan infections of the GIT?

Answer 2

Giardia
Entamoeba
Cryptosporidium

Question 3

Hygiene 101: How do you prevent food-borne illness?

Answer 3

Peel it, Cook it, Boil it

Question 4

What are the virulence factors of E. coli?

Answer 4

• Fimbriae (allow for colonization)
• Adhesins (allow for cell invasion)
• Toxins (endo=part of cell; or exo=secreted such as LT, ST, or Shiga-toxin)

Question 5

What is STEC?

Answer 5

STEC = EHEC
STEC = "Shiga Toxin producing E. coli"

Question 6

What does the O157:H7 refer to?

Answer 6

The serotype of E. coli:
O157 is the somatic antigen
H7 is the flaggelar antigen

Question 7

What is the recommended treatment of EHEC?

Answer 7

Supportive measures;

Do not give Abo due to risk of HUS.

Question 8

What is the reservoir for Salmonella typhi?

Answer 8

Humans (not other animals)

Question 9

What are the main virulence factors of Salmonella typhi?

Answer 9

• Vi capsular antigen (inhibits phagocytosis)

Question 10

What is the treatment of Salmonella typhi?

Answer 10

Antibiotics - based on susceptibility - increasing resistance especially to Cipro

Question 11

What are clinical symptoms associated with Salmonella typhi?

Answer 11

• Gastroenteritis (Diarrhea &/or constipation)
• Typhoid fever (invasion of Peyers patches in gut, then blood –> fever, rash, headache, ileum perforation)
• May be asymptomatic

Question 12

What is the reservoir for campylobacter?

Answer 12

Poultry - chicken

Question 13

What are the clinical symptoms of campylobacter?

Answer 13

• Diarrhea
• Reactive arthritis
• Guillain Barre syndrome (ascending paralysis)

Question 14

What is the treatment for Campylobacter?

Answer 14

It’s self-limiting; therefore, no Abo tx unless severe or immunocompromised.

Question 15

Give an overview of the Giardia lifecycle

Answer 15

Eat in cyst form;
Exits in feces in trophozoite form and cyst form;
Trophozoites do not survive in the environment;
Giardia is a cyst in its infective stage.

Question 16

What are the symptoms of Giardia infection?

Answer 16

• Diarrhea
• Steatorrhea
• No fever

Question 17

What are clinical findings for Entamoeba infection?

Answer 17

• 90% of patients are asymptomatic
• diarrhea
• chronic disease mimicking IBD

Question 18

What are imaging findings for Entamoeba infection?

Answer 18

Enlarged liver on CT and raised right hemidiaphragm.

Question 19

Briefly, what is the lifecycle of Entamoeba?

Answer 19

Mature cysts are ingested;
Enters GI tract, then skin, then liver, lungs, & brain;
Trophozoites and cysts passed in feces.

Question 20

What is the treatment for Entamoeba?

Answer 20

Metronidazole - kills trophozoites

Paromomycin/Loqoquinol - kills cysts

Question 21

What are the symptoms of cryptosporidium infection?

Answer 21

• Abd cramping/pain
• dehydration
• nausea
• vomiting
• fever
• weight loss

Question 22

Treatment of cryptosporidium?

Answer 22

Usually self-limiting.

Nitazoxanide is a new drug ~$3000/wk

Question 23

What is the toxin for C. diff?

Answer 23

Binary toxin –> A (enterotoxin) and B (cytotoxin)

Question 24

What are some risk factors for C. diff infection?

Answer 24

• Hospitalization
• Broad-spectrum Abo
• PPIs (b/c they reduce effect of gastric acid in killing spores
• Multiple co-morbidities

Question 25

Clinical Presentation of C. diff?

Answer 25

Diarrhea (watery, foul-smelling)
Increased WBC
Mild abd discomfort/pain

Question 26

What are some complications of C. diff infection?

Answer 26

• Pseudomembranous colitis
• Toxic megacolon
• Intestinal perforation
• Sepsis
• Death