Intestinal Infections - Mclean

Question 1

ALL TARGET QUESTIONS:

a.) Vibrionaceae disease and characteristic of it:
b.) EHEC (Enterohemorrhagic) involved with which syndrome?
c.) Contaminated ground beef associated with what serotype?
d.) Shigella virulence
e.) Similarities and differences between shigella and salmonella
f.) Vibrio cholerae Characteristics and symptoms

Answer 1

a.) Diarrhea. Looks like Rice water + mucus.
b.) Hemolytic Uremic Syndrome (HUS) leading to acute renal failure. Leads to anemia, platelet levels going down, kidney problems.
c.) Serotype O157:H7. Most common in USA. Type of EHEC. Cattle intestine is a major reservoir for this serotype.
d.) Shiga exotoxin - inhibit protein synthesis, damage intestinal epithelium and glomerular endothelium
e.)
f.) Produce cholera enterotoxin (Choleragen). Increase cAMP, increases HCl production. Watery diarrhea (rice water) with mucus

Question 2

Serologic classification: 3 major group of antigens:

Answer 2

O antigens: Somatic / cell wall
H antigens: Flagellar
K antigens: Capsule

Question 3

Flagellar Antigens

Answer 3

Denatured by heat
Protein in nature

Question 4

Capsular Antigens

Answer 4

(K)
K antigens
Vi antigen (subtype of K)-> Salmonella typhi ***
Most are polysaccharides
Antiphagocytic, increase virulence

Question 5

Enterobacteriaceae General properties

Answer 5

Gram-negative rods.
Nonfastidious
Facultative anaerobes

Some have capsule, some are motile
Ferment sugars
Great antigenic variation
Engage in genetic exchange (conjugation / transduction)

Question 6

3 Main members of Enterobacteriaceae:

Answer 6

E coli
Salmonella
Shigella

Question 7

3 Main types of Salmonella

Answer 7

Typhoid fever (most common)
Bacteremia
Enterocolitis

Question 8

Escherichia coli (e coli)

Answer 8

Small, straight Gram - rods, occur singly
Ferment lactose (salmonella and shigella do not do this)
Can be pathogenic, some have capsule, usually motile

Question 9

Major classes of pathogenic E. coli:

Answer 9

Enteropathogenic
Enteroaggregative
Enteroinvasive
Enterotoxigenic
Enterohemorrhagic
Nephropathogenic

PAITH nephro

Question 10

ETEC (enterotoxigenic) virulence/treatment:

Answer 10

Enterotoxins:
LT (heat labile) - activate cAMP
ST (heat stable)- activate cGMP

Treatment: Antibiotics are contraindicated- increase toxin production.

Question 11

EHEC virulence:

Answer 11

Exotoxin:
Shiga-like toxin or VEROTOXIN (similar to Shigella dysentery toxin)

Question 12

Helicobacter pylori metabolism

Answer 12

Urease positive. Ammonia protects h pylori from acidic environments
Mucinase (facilitates tissue penetration)

Use breath test to detect.

Question 13

Clostridium perfringens

Answer 13

Anaerobic, so use hyperbaric oxygen to treat