Gastrointestinal Pathogens

Question 1

What does ETEC stand for?

Answer 1

Enterotoxigenic

ETEC is associated with diarrhea in tropical and subtropical climates.

Question 2

What type of diarrhea is commonly associated with ETEC?

Answer 2

• Diarrhea for people in tropical/subtropical climate
• Infant bacterial diarrhea
• Traveler’s diarrhea

ETEC is linked to poor hygiene and sanitation, particularly in third world countries.

Question 3

What is the infective dose range for ETEC?

Answer 3

10^6 to 10^10 organisms

This high infective dose indicates the number of organisms needed to cause infection.

Question 4

What allows ETEC to bind to intestinal microvilli?

Answer 4

Fimbriae

After binding, ETEC releases heat-labile toxin (LT) and heat-stable toxin.

Question 5

Is ETEC disease self-limiting?

Answer 5

Yes

ETEC infections typically resolve without extensive medical intervention.

Question 6

What does EPEC stand for?

Answer 6

Enteropathogenic

EPEC requires certain O and H serogroups for infection.

Question 7

Where is EPEC commonly found?

Answer 7

• Hospital nurseries
• Daycare centers

EPEC causes a specific type of diarrhea characterized by a lot of mucus.

Question 8

What type of dysentery does EIEC produce?

Answer 8

Enteroinvasive Escherichia coli

Dysentery with direct penetration, invasion, and destruction of intestinal mucosa

EIEC is rare in the US and is similar to Shigella.

Question 9

What does EHEC stand for?

Answer 9

Enterohemorrhagic

An example of EHEC is O157:H7.

Question 10

What are the symptoms of EHEC infection?

Answer 10

• Hemorrhagic diarrhea
• Colitis
• Hemolytic uremic syndrome (HUS)

EHEC can be potentially fatal, especially in young children and elderly adults.

Question 11

What types of food are commonly associated with EHEC infections?

Answer 11

• Undercooked processed meats (like hamburgers)
• Unpasteurized dairy
• Apple cider
• Spinach

These foods can harbor EHEC bacteria, leading to severe illness.

Question 12

What are the cytotoxins produced by EHEC?

Answer 12

• Verotoxin I
• Verotoxin II

These toxins are similar to shiga toxin.

Question 13

What is the purpose of SMAC in testing for O157:H7?

Answer 13

*Contains sorbitol instead of lactose
* Differentiate O157:H7 from othe E. coli

E. coli O157:H7 appears colorless with heavy growth on SMAC.

Question 14

What does the MUG assay test for?

Answer 14

Screening isolates for O157:H7

O157:H7 rarely produces the enzyme β-glucuronidase.

Question 15

What does ELISA immunoassay detect?

Answer 15

O157 antigen

This assay is used for identifying EHEC infections.

Question 16

What does STEC stand for?

Answer 16

Shiga toxin producing E. Coli

STEC can be identified by finding shiga toxin in stool or a significant increase in shiga toxin neutralizing antibody titer.

Question 17

What does DEAC stand for?

Answer 17

Enteroadherent

DEAC is associated with UTIs and diarrheal disease.

Question 18

What conditions are associated with DEAC?

Answer 18

• UTIs
• Cystitis in children
• Acute pyelonephritis in pregnant women
• Chronic UTIs

DEAC can lead to significant urinary tract issues.

Question 19

What does EAEC stand for?

Answer 19

Enteroaggregative

EAEC causes diarrhea by adhering to the surface of intestinal mucosa.

Question 20

How do EAEC bacteria appear in stool?

Answer 20

No pus cells or red blood cells

EAEC is an important cause of diarrhea in infants and immunodeficient individuals.