Term
| What are the major enteric bacteria with a type III secretion system? |
|
Definition
E.coli
Yersina
Salmonella
Shigella
Vibrio cholera |
|
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Term
What are the lactose fermenters grown on Maconkey or EMB agar?
Which is indole (+)? |
|
Definition
E.coli-Indole (+)
Klebsiella
Enterobacter |
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Term
| What are the virulence factors of E.coli |
|
Definition
Enterotoxins:
LT:ADPR->Gs like cholera(secretes ions)
ST:cGMP(decreases ion absorption)
Cytotoxins(shiga-like)
Type III Secretion
Endotoxin
Capsule
Bundle Forming Pillus |
|
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Term
What group of e.coli stains has prominent blood in the stool?
Which has prominent WBC's in the stool? |
|
Definition
|
|
Term
| Which type of E.coli strains cause hemolytic uremic syndrome and why? |
|
Definition
EHEC
Bc the Cytotoxin(shiga-like) has a predilection for the GB3 which predominate in the kidneys and GI |
|
|
Term
| What are the main virulence factors of each of the types of E.coli stains? |
|
Definition
ETEC(1A:5B):
LT-ADPR transferase activating adenylate cyclase
ST-peptide activating Guanyl Cyclase
EPEC:
Bundle forming pillus
Type III secretion-Injects TIR(autoreceptor), peptides for actin rearrangement(pedicles)
EHEC:
Cytotoxin(Shiga-like)
Type III secretion |
|
|
Term
| What is the pathogenesis of the lesions seen in EPEC |
|
Definition
Attachment and Effacement lesions with loose villus structure and bacteria on pedicles
Injection of Tir by Type III secretion allows strong attachment
Other injected factors rearrange the cytosolic structure of the microvilli |
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|
Term
| What are the lab Characteristics of E.coli |
|
Definition
Gram (-) Rod
Lactose Fermenter
Indole (+) |
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Term
| What are the lab characteristics of Vibrio cholera |
|
Definition
Gram (-) Comma-shaped Rod
Oxidase (+)
Motile |
|
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Term
| Which vibrio strain is responsible for epidemics and which type causes most pandemics? |
|
Definition
Epidemics: V. cholera O1(El Tor and Classic)
Pandemics: El tor |
|
|
Term
| What are the major virulence factors of V.cholera |
|
Definition
Cholera toxin: ADPR-> AC-> cAMP
Adhesins
Mucinase |
|
|
Term
| What is the major clinical feature of V. cholera infection and how does it cause death? |
|
Definition
Rice water stool
profound dehydration |
|
|
Term
| Does immunity to V.cholera prevent reinfection? |
|
Definition
|
|
Term
| What areas are hotspots for cholera |
|
Definition
Brazil, Peru
Northern Africa
Southeast Asia
Lousiana
Texas |
|
|
Term
How is Vibro parahemolyticus typically transmitted?
Does the infection produce blood? |
|
Definition
Raw or Undercooked Seafood
Frequently on cruiseships
Blood: Occasionally blood in the stool |
|
|
Term
Who most commonly gets a vibrio vulnificus infection?
Who gets a more severe infection? |
|
Definition
Common: Shellfish handlers in the Gulf of Mexico
Severe(Rapidly fatal Septicemia):
Immunocompromised eating raw shellfish
People with chronic liver disease |
|
|
Term
What are the lab characteristics of Clostridium difficile?
What people have the highest carrier rates? |
|
Definition
Lab:
Large Gram(+) Spore-forming Rod
Obligate Anaerobe
Carriers: Common in health-care workers
|
|
|
Term
When does C.difficile typically cause infection?
What is a severe manifestation? |
|
Definition
Antibiotic therapy allows resistant C.diff growth
Pseudomembranous colitis: layer of fibrin, mucus, leukocytes and necrotic cells
Toxic Megacolon |
|
|
Term
| What are the toxins of C.diff and what are their effects? |
|
Definition
Toxin A(enterotoxin): Fluid secretion and Hemorrhagic Necrosis
Toxin B(Cytotoxin): Blocks Protein Synthesis |
|
|
Term
| How is C.diff diagnosed and treated |
|
Definition
DX
Toxin Detection
Endoscopy
TX
Antibiotic discontinuation
Metronidazole or Vancomycin |
|
|
Term
| What do the O, H, and K antigens refer to? |
|
Definition
O: Polysachirides
H: Flagellar
K: Capsular |
|
|
Term
How does MacConkey agar and EMB agar inhibit gram (+) growth?
How do lactose fermenters appear on each? |
|
Definition
Mac: Bile salts
Lac-Purple/Red
EMB: Aniline Dyes
Lac: Black/Green(Strong fermenters)
Pink-Purple(Mild fermenters) |
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|
Term
What virulence factor is important to the K1 strain of E.coli?
What disease does this strain cause? |
|
Definition
|
|
Term
| What bacterial enteritis can you detect toxin in the stool? |
|
Definition
|
|
Term
Which Toxins increase cAMP
Which Toxins increase cGMP
What toxins are Cytotoxins?
What toxins are Emetic? |
|
Definition
cAMP
LT E.coli toxin
B. cereus LT toxin
Cholera toxin
cGMP
E.coli ST toxin
Y. Enterolytica ST toxin
Cytotoxin
EHEC Verotoxin
Shiga Toxin
C.diff B toxin
Emetic
Staph Enterotoxin
B.cereus ST Toxin |
|
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Term
| What is the media used to culture V. cholera |
|
Definition
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