Enteric Bacteria I+II

Question 1

Noninvasive bacteria

Answer 1

1. V. Cholerae
2. ETEC
3. EPEC
4. EHEC

*all ecoli other than EIEC

Question 2

Invasive bacteria

Answer 2

1. Shigella
2. EIEC (enteroinvasive e.coli)
3. Salmonella
4. Yersinia
5. Campylobacter

Question 3

Sources of enteric pathogens

Answer 3

1. vegetables
2. beef
3. milk
4. eggs
5. poultry

Question 4

Which enteric bacteria infxns peak in the summer? Winter?

Answer 4

Summer:

1. campylobacter
   - heat tolerant
2. salmonella
3. E. coli

Winter:
Yersinia

Question 5

O157 is located where in e.coli?

Answer 5

present in flagellum

Question 6

Pili are used for adhesion, what 2 special properties aid to this?

Answer 6

inhibits competition

tropism

• tissue of host aides growth
• by hanging on better, can use host to advantage

Question 7

Shellfish

Answer 7

V. cholera

• estuarine and marine environments
• eat shellfish –> now you poop and spread in household if poor sanitation

Question 8

Virulence factors of V. cholera

Answer 8

Colonization: TCP co-regulated pilus

Enterotoxin: cholera toxin

Question 9

toxic part of LPS

Answer 9

Lipid A

Question 10

Pathogenicity islands

Answer 10

specific regions of DNA found only in chromosomes of pathogenic strains encode virulence factors

• ie: invasion genes, or toxins

Question 11

Which is primarily toxigenic and which is primarily invasive?
V. Cholerae
Salmonella

Answer 11

Toxigenic: V. cholerae

Invasive: salmonlella

*note that shigella is both

Question 12

Cholera causes profuse watery diarrhea using an ______. How long does it incubate?

Answer 12

enterotoxin
- an exotoxin that acts at intestines

*they incubate and prod. this over 2-5 days.

Question 13

Does cholera cause:
vomiting?
fever?
abrupt or slow onset diarrhea?

Answer 13

Some vomiting
No fever
Abrupt onset diarrhea

Question 14

Fxn of A-B type toxin of cholera

Answer 14

B subunit binds cell surface receptors (ganglioside GM1)

A subunit enters the cell cytoplasm and activates Gs –> adenylate cyclase –> cAMP

Question 15

Heat-labile enterotoxin vs

Heat-stable enterotoxin

Answer 15

Heat labile: activates cAMP

Heat stable:
activates cGMP

*eL Agua
de
San Gabriel

Question 16

Organisms with type III secretion systems

Answer 16

EPEC
Shigella
Salmonella
Yersinia

*secretes translocated-intimin receptor, allowing for attachment and effacement lesions –>
microvilli destruction –>
interferes with absorption

Question 17

antibiotics recommended for EHEC?

Answer 17

No

*also not recomm. for travelers diarrhea

Question 18

difference between shiga toxin and shiga like toxin

Answer 18

They are same:

Stx and SLT: Inactivates 60s by removing adenine from rRNA
- binds to sphingolipids of enterocytes and renal endothelial cells

• only shigella is invasive

Question 19

Major initial targets of entry for invasive pathogens

Answer 19

Intestinal epithelial M cells:

- antigen-sampling cells that overly the lymphoid follicles of the gut

Question 20

Which type of Shigella makes Shiga toxin?

Answer 20

Only S. dysenteriae Type I

- causes epidemic dysentery

Question 21

Transmission of shigella

Answer 21

4 F’s

1. Food
2. Fingers
3. Feces
4. Flies

Question 22

First and second leading cause of bacterial gastroenteritis

Answer 22

1. Campylobacter

2. Salmonella

Question 23

How long after ingestion does Salmonella induced gastroenteritis present?

Answer 23

24-48 hours after ingestion.

Question 24

Is N/V present in salmonella and shigella infxns?

Answer 24

Salmonella enteriditis only
- followed by chills, fever, cramps, watery diarrhea

• self limiting, do not require ab tx
• tx w/ S. typhi for tyhoid fever.

Question 25

Yersinia enterocoliticia affects which part of the intestines?

Answer 25

Terminal ileum | - pseudoappendicitis

Question 26

Organisms that can cause Reiters syndrome

Answer 26

1. Yersinia 2. Campylobacter *commonly occurs in HLA B27 indiv.

Question 27

Complications of Campylobacter

Answer 27

1. Guillain-Barre syndrome - ab response against O antigen --> cross react with sphingomyelin --> demyelinates nerves 2. Reiters syndrome - autoimmune reactive arthropathy

Question 28

Treatment for campylobacter is usually fluid replacement, what about when it is severe?

Answer 28

Erythromycin or quinolones

Question 29

The most common hu bacterial pathogen

Answer 29

H. pylori | - primarily in gastric mucosa

Question 30

Virulence factors of H. pylori

Answer 30

1. Highly motile - reach less acidic environment of gastric epithelium 2. Powerful urease production - makes NH3 --> raises pH 3. Has pathogenicity islands encoding virulence genes

Question 31

When are H. pylori infxns typically acquired?

Answer 31

In childhood

Question 32

Gold std of diagnosing H. pylori

Answer 32

histological examination of multiple biopsies followed by culture and isolation of organism

Question 33

tx for H. pylori

Answer 33

``` triple therapy 1. PPI 2. BIsmuth 3. Tetracycline (helidac) for 14 days ```

Question 34

Which organisms have NADPH activity?

Answer 34

1. Listeria - NADPH oxidase cannot be assembled to make O2 --> superoxide --> ROS and it lyses and escapes the phagosome 2. Legionella - inhibits mobilization of cytosolic components of NADPH oxidase to membrane 3. Salmonella - uses superoxide dismutase and catalase to detoxify ROS