Gi Pathogens

Front 1

Enteritis

Back 1

Inflammation of the mucosa of the intestines

Front 2

Enterocolitis

Back 2

Enteritis involving both small and large intestines

Front 3

Gastroenteritis

Back 3

Inflammation of both stomach and intestinal linings

Front 4

Diarrhea

Back 4

Symptoms include frequent/fluid stools and electrolyte loss

Front 5

Dysentery

Back 5

Inflammation of GI tract w/ blood and pus in the feces, symptoms of pain and fever.

Normally a disease of the large intestine.

Front 6

What are the 2 families of Enteric Bacilli?

Give some examples.

Back 6

1. Enterobacteriaceae
-Lactose fermenters (Coliform bacteria) = E. coli, Klebsilelle, Enterobacter, Serratia
-Lactose non-fermenters = Salmonella, Shigella, Proteus, Yersinia

2. Vibrionaceae
-Polar flagella, oxidase-positive
- Vibrio cholerae

Front 7

What are the common features of the enteric bacilli?

(4)

Back 7

1. Gram neg. rods
2. Facultative anaerobes
3. Grow in simple media
4. Ferment glucose

Front 8

O Antigen

Back 8

Polysaccharide portion of LPS

Front 9

H Antigen

Back 9

flagella protein found on motile cells

Front 10

K Antigen

Back 10

Capsular polysaccharide

Front 11

What test would tell you if you have Lac+ vs. Lac-?

Back 11

MacConkey Lactose Agar

(also selects for gram neg.)

Front 12

List the 5 types of pathogenic Escherichia coli

Back 12

1. ETEC = Enterotoxigenic
2. EPEC = Enteropathogenic
3. EHEC = Enterohemorrhagic
4. EIEC = Enteroinvasive
5. EAggEC = Enteroaggregative

Front 13

General features of Pathogenic E. coli

(3)

Back 13

1. Lac+ Enterobacteriaceae
2. Normal flora of GI
3. Pathogenic when it posses a virulence factor not normally found in the GI flora

Front 14

ETEC: Enterotoxigenic E. coli

Back 14

Diseases: Traveler's Diarrhea (montezuma's revenge). Found in uncooked foods/unpeeled fruits, cold drinks

Virulence Factors:
1. Heat-Labile Toxin (LT) = just like Cholera toxin (Gs stim. via glycosylation)
2. Heat-Stable Toxin (ST) = stim. guanylate cyclase = anti-absorptive mechanism by inhibiting NaCl absorption
3. Type 1 pili (binds D-mannose) = adhesion
4. Colonization factor antigens (CFA) = pili/fimbriae

Front 15

EPEC: Enteropathogenic E. coli

Back 15

Diseases: MCC infant diarrhea (watery), usually self-limiting

Virulence Factors:
1. Adhesins (BfpA = bundle-forming pilus) allow for initial attachment to small bowel
2. Type III Secretion/Intimate Adherence = actin rearrangement/pedestal formation for attachment

Front 16

EHEC: Enterohemorrhagic E. coli

Back 16

Very Acid-tolerant, only need 10 bugs b/c they can make it through the stomach

Diseases:
1. Hemorrhagic Colitis (BLOODY diarrhea, like Shigella, Salmonella)
2. O157:H7 = biggest group. SORBITOL NONFERMENTING (can use a Mac-sorbitol agar)
3. Hemolytic-Uremic Syndrome (HUS) = kidney failure. SLT goes to kidney. MCC acute renal failure in kids in USA
Virulence Factors:
1. Shiga-like toxin (SLT) = stops protein synth (28S rRNA modification) = intestinal epithelial lining cooked.
2. EPEC-like binding (Intimin, type III, actin-polymerize)
3. Acid resistance

Front 17

EIEC: Enteroinvasive E. coli

Back 17

Diseases:
1. Dysentery (like Shigella) via invasion of epithelial cells. Less severe than Shigella

Virulence Factors:
1. Plasma-encoded invasion factors (like Shigella)
2. Actin mobilization like Lysteria
3. Type III/membrane reffling/actin rearrangement/bacterial engulfment

Front 18

EAggEC: Enteroaggregative E. coli

Back 18

Disease:
1. Persistent childhoot watery diarrhea

Virulence Factors:
1. Fimbrial adhesions

not well understood

Front 19

Other E. coli infections:

Uropathogenic E. coli

Back 19

UTIs

MCC cystitis

Virulence Factor:
1. P-fimbriae allows adherence to upper urinary tract

Front 20

Other E. coli infections:

E. coli systemic opportunistic infections

Back 20

MCC nosocomial gram-neg. bacteremia

Death can occur via endotoxin shock