Term
| What two events usually occur during colonization of a host? |
|
Definition
Adherence to tissue
Multiplication
21-2 |
|
|
Term
| How are pathogens able to colonize host tissue, when it's already crowded by normal flora? |
|
Definition
Novel pili that allow it to attach to sites where the flora is not attaching.
21-2 |
|
|
Term
| Contrast pili from nonfrimbrial adhesions. |
|
Definition
Pili: Long-range
Nonfimbrial adhesions: Short-range
21-2 |
|
|
Term
| What are the 4 characteristics of Enterobacteriaceae? |
|
Definition
Facultative anaerobes
Oxidase negative
Can grow on media w/ only glucose
Bile resistant
21-4 |
|
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Term
| You culture an enteric on a MacConkey agar plate. It grows clear colonies at 24 hours. Which of the following could NOT be this organism:
a. Shigella dysenteriae
b. E. coli
c. Proteus mirabilis
d. Morganella morganii |
|
Definition
| E. coli. It is lactose positive and would not form clear colonies. It would be red.
21-5 |
|
|
Term
| What are 3 general virulence factors for E. coli? |
|
Definition
Fimbrial and afimbrial adhesions
Iron acquisition
Toxins
21-7 |
|
|
Term
| Name the most common manifestation of this organism: ETEC. |
|
Definition
Traveller's diarrhea.
21-8 |
|
|
Term
| Name the most common manifestation of this organism: EPEC. |
|
Definition
Infant diarrhea in developing countries
21-8 |
|
|
Term
| This strain of E. coli forms a "pedestal" with the proteins intimin, and TIR, but not Stx. |
|
Definition
|
|
Term
| This strain of E. coli forms a biofilm that colonizes the gut under the mucus layer. |
|
Definition
|
|
Term
| This strain of E. coli forms a type III secretion system and invades the cytoplasm of host cells. |
|
Definition
|
|
Term
| Does S. saprophyticus cause CA UTI's or nosocomial UTI's? |
|
Definition
|
|
Term
| Which adhesin protein is associated with pyelonephritis? |
|
Definition
|
|
Term
| What is the important antigen in E. coli that causes neonatal meningitis?
a. E44
b. K1
c. O42
d. K7 |
|
Definition
|
|
Term
| For what E. coli infection are antibiotics actually contraindicated? |
|
Definition
Hemolytic uremic syndrome (HUS)
21-12 |
|
|
Term
| T/F More people are colonized with H. pylori outside of the US than within. |
|
Definition
|
|
Term
| Name 5 virulence factors for H. pylori. |
|
Definition
Urease
Flagella
VacA: cytotoxin that can damage stomach cells
Type IV secretion system
CagA: the last to referred to as cag pathogenicity island
21-14 |
|
|
Term
| Colonization involves TWO (fairly obvious) aspects. What are they? |
|
Definition
Adherence and multiplication.
(Syllabus: 21-2) |
|
|
Term
What do bacteria use for
a) long-range attachment, and
b) short-range attachment
?
|
|
Definition
a) Pili
b) Non-fimbrial adhesins
(Syllabus: 21-2) |
|
|
Term
| Tell me about enterobacteriaceae. How do they Gram stain and what shape are they? Where are they found? Are they anaerobes or aerobes or what? Are they oxidase positive or negative? On what media do you grow/isolate them? |
|
Definition
Enterobacteriaceae are Gram negative rods that are often part of the normal GI flora. They are facultative anaerobes but are oxidase-negative (they have some other enzyme that they use in place of cytochrome C). They grow well on simple media using just glucose as an energy source, but you can use MacConkey agar to isolate them. (That's because MacConkey has bile salts, which the enterbacteriaceae can tolerate, but many other bacteria cannot.) Some enterbacteriaceae eat the lactose in the MacConkey agar; they produce lactic acid, which turns the pH-sensitive media PINK.
(Syllabus: 21-4) |
|
|
Term
| Name six important members of the enterobacteriacea. |
|
Definition
Shigella
Salmonella
Escherichia
Klebsiella
Proteus
Yersinia
(Mnemonic: SEKSY P. Mmm, that is one sexy pea that I'll eat and send to my GI tract.)
(Syllabus: 21-5) |
|
|
Term
| You have some enterbacteriaceae on a nice plate of MacConkey agar. How can you determine if they are Escherichia, Salmonella, or Shigella? |
|
Definition
Eschericia eat lactose; the others don't. (Escheria turn MacConkey agar pink.)
Salmonella makes hydrogen sulfide (H2S); the others don't.
(Syllabus: 21-5) |
|
|
Term
| Some members of enterobacteriaceae cause opportunistic infections. What is the most common type of infection that they cause? |
|
Definition
Urinary tract infections.
(Syllabus: 21-5) |
|
|
Term
| What are the three antigens used to distinguish different strains of E. coli? |
|
Definition
O (surface--LPS), H (flagella), and K (capsule).
(Syllabus: 21-6) |
|
|
Term
|
Definition
Molecules with a high affinity for iron. E. coli produce them to steal our iron. Jerks!
(Syllabus: 21-7) |
|
|
Term
| E. coli can produce up to five toxins. What are they, and what do they do? |
|
Definition
Endotoxin (LPS): Summons a powerful immune response.
Hemolysin (Hly): Can damage kidney cells (possibly leading to pyelonephritis).
Heat-stable enterotoxin (STa): Increases cGMP levels in enterocytes; this somehow causes diarrhea.
Heat-labile enterotoxin (LT): Increases cAMP levels in enterocytes; again, diarrhea.
Shiga toxin (STX): Inactivates ribosomes, preventing protein synthesis--especially in kidney cells.
(Syllabus: 21-7) |
|
|
Term
| E. coli can produce five kinds of infection. What are they (and what do the acronyms mean?) |
|
Definition
ETEC: Enterotoxigenic E. coli
EPEC: Enteropathogenic E. coli
EAEC: Enteroaggregative E. coli
EIEC: Enteroinvasive E. coli
EHEC: Enterohemorrhagic E. coli
(Syllabus: 21-8) |
|
|
Term
| I really want to get ETEC. How would I go about getting it, and what would I enjoy as my symptoms? |
|
Definition
It's transmitted by contaminated food and water. It causes watery diarrhea.
(Syllabus: 21-8) |
|
|
Term
| What's a Type III secretion system? |
|
Definition
It's a way for Gram-negative bacteria to excrete proteins directly from their cytoplasm to the external environment. It's like a tube or syringe.
(Syllabus: 21-9) |
|
|
Term
| Which E. coli infections use a Type III secretion system? |
|
Definition
EPEC, EIEC, and EHEC.
(Syllabus: 21-8 and 9) |
|
|
Term
| Hello. I'm an E. coli bacterium. I like to cruise down the epithelium with my bundle-forming pilus (bfp) dangling, until it grabs onto a nice, juicy cell. Then I get down to business. What kind of infection do I cause, and what are the symptoms? |
|
Definition
I am EPEC. After grabbing the cell, I use my Type III secretion system to create a close attachment to my host cell and I rise up on a pedestal. I like to cause diarrhea in infants.
(Syllabus: 21-8 and 9) |
|
|
Term
| A biofilm is characteristic of which E. coli infection? |
|
Definition
EAEC (enteroaggregative E. coli).
(Syllabus: 21-9) |
|
|
Term
| THIS E. coli infection resembles Shigella, both in pathogenesis and disease symptoms. |
|
Definition
What is EIEC (enteroinvasive E. coli)?
It doesn't produce enterotoxins, though it does cause diarrhea.
(Syllabus: 21-9 and 10) |
|
|
Term
| THIS E. coli infection is like EPEC, but with Shiga toxin. |
|
Definition
What is EHEC (enterohemorrhagic E. coli)?
(Syllabus: 21-10) |
|
|
Term
| What is hemolytic uremic syndrom (HUS), and how do you get it? |
|
Definition
It's acute kidney failure, usually as a result of EHEC. (Shiga toxin can affect the kidneys.)
(Syllabus: 21-10) |
|
|
Term
| What bacterium is the most common cause of community-acquired urinary tract infections? |
|
Definition
E. coli.
(Syllabus: 21-11) |
|
|
Term
| What are the two leading causes of neonatal meningitis? |
|
Definition
E. coli and Group B strep.
(Syllabus: 21-11) |
|
|
Term
TRUE OR FALSE:
I should treat HUS with antibiotics. |
|
Definition
FALSE. (Unless you don't like your patient.)
(Syllabus: 21-12) |
|
|
Term
| Compare and contrast the morphology and biological properties of H. pylori and C. jejuni. |
|
Definition
They are both curved, Gram-negative rods that are motile and microaerophilic. H. pylori grows well at 37°C, while C. jejuni prefers a tropical 42°C.
(Syllabus: 21-12) |
|
|
Term
H. pylori is a Sith lord, fighting a jedi neutrophil above the bubbling, acidic pit of the stomach. The neutrophil force-pushes the H. pylori into the stomach acid--surely it's curtains for the dark lord!
But no... Darth Pylori manages to survive in that acidic cesspool. HOW???? |
|
Definition
H. pylori produces urease, which raises the pH in its immediate vicinity. It also uses its flagellum to move into the mucus layer, where the pH is much higher than in the acid.
(Syllabus: 21-14) |
|
|
Term
| Most stomach and duodenal ulcers stem from what bacterium? |
|
Definition
H. pylori.
(Syllabus: 21-15) |
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