lecture 10

Question 1

What are some characteristics of enterhemmoragic ecoli?

Answer 1

• they are facultive anaerobes and can respirate using oxygen or ferment without O2
• The optimum temperature is 37 degrees celsius
• Ecoli can survive anywhere between 4-45 degrees celsius
• they grow at water activity of .90 and higher
• survive fermentation in addition to the drying of storage of sausage for 2 months due to protection by animal fat
• inactivated by heat
• inactivated by radiation

Question 2

Resovoirs:

Answer 2

-Mainly located on cattle, sheep, deer, cat, rodents, dogs, horses and seaguls
-Also located in agricultural water and manuer fertilizers
which can contaiminate crops and drinking water
-can infect people by contaminting lakes, swimming pools, water parks and drinking water.

Question 3

Most commonly associated foods:

Answer 3

-beef, dairy, produce, cake, ice cream
In order of occurance
1)beef
2)leafy vegetables
3) diary products

Question 4

how much E.coli does it take to infect a person?

Answer 4

It takes 1-100cells to infect someone. Food bourne outbreaks occur with low amounts:
It takes as little as
.3-15CFU-E.coli O157:H7 per gram of frozen ground beef patties
.3-.4CFU-E.coli O157:H7 per gram of salami
to cause an outbreak

Question 5

E.coli O157:H7 symptoms

Answer 5

Can vary from no symptoms to mild diareah to hemmoragic colitis

• Form of severe diareah which is bloody in 70-90 percent of the cases
• stomach pain and throwing up
• the symptoms last for anywhere between 5-7 days
• may still be present in feces for more than 3 weeks

Question 6

Post infectious disorders

Answer 6

hemolytic uremic syndrome-kidney failure

thrombotic thrombocytopenic purpura (TTP)-reduction in blood platelets

Question 7

Treatment

Answer 7

Should not use antiobiotic as it may make the disease worse by releasing endotoxins and shigatoxins from the bacteria that it kills (Known to be released by dead bacteria).

Question 8

What are some virulence factors of Ecoli 015H7

Answer 8

Enterohemmoragic bacteria

1. Stx 1 or shigatoxin 1 produced by ecoli is almost identifcal to shigatoxin dysenteriae type 1 produced by shigella.
2. Stx 2 is most often associated with hemolytic uremic syndrome which results in acute renal failure or failure of the kidney.

all Shigatoxins (whether stx 1 or stx2) work by binding to G3 glycolipids located in on kidney cells. Whether or not illnesses develop or how serious these illnesses are when they do develop depends upon the number of stx toxins that are able to pass through the intestinal epilitheum barrier.

Question 9

Describe the pathogenisis cylcle of ecoli O157:

Answer 9

Pathogenisis can occur in two possible mechanisms:
1)Inserts a TTSS receptor on to the cell and then releases one of it’s proteins called interim which will bind to the ttss receptor and allow the bacteria to release other proteins into the cell which will cause rearrangements of the ccell cytoskeleton. An example of such a rearrangement is the removal of microvilli on the surface of the cell causing a feature known as ACE lesion.

2) Ecoli O157 can also enter peyers patches, be consumed by macrophages in lamina propria. It then can survive and produce shiga toxin which will cause the macrophage to die of programmed cell death and then release into the body to travel to other areas of the body such as the
-brain
-intestine
-kidney
to cause other major illnesses

Question 10

Vibrio species taxonomy:

Answer 10

Phylum: proteobacteria
Class: Gamma proteobacteria
Species:
V. cholera-causes cholera a diareahal illness. Found in seawater
V. vulfificus- most often found in raw oysters
V. Parahelmiths-most often found in raw oysters

Question 11

Resovoirs:

Answer 11

-located in esutaries, aquatic and marine habitats put their through fecal contamination
-colonize sea invertebrates
-can be free living
-attached to plankton
- mostly found in sea or brackish water
Over 80 species and at least 12 cause diseases in people
-also attach to surfaces through biofilms
-most popular in summer months where they are commonly found attached to shellfish, oysters and mollusks

Question 12

What are some of the most important pathogens that comes from seas, lakes and ponds:

Answer 12

• V. vulnificus

- V. parahelmithus

Question 13

How does parahemolyticus differ from vibrivulnificus

Answer 13

Parahelmithus is a milder disease which usually does not result in death. Whereas v. vulnficus does result in death.

Question 14

What are some of the characteristics of vibrio?

Answer 14

• non moving

- Facultive anaerobes-

Question 15

What are some of the resovoirs that vibrio grow in?

Answer 15

-found mainly in seawater