Session 4

Question 1

what is the process of gram staining

Answer 1

1. smearing bacteria onto a slide
2. Adding crystal violet and iodine
3. Adding saffrin
4. Creating gram + and Gram - bacteria

Question 2

Differences between gram + and gram - bacteria

Answer 2

Gram +

Question 3

Char. of staph aureus

Answer 3

Aerobic: 
-ph: 4.2
-aw-.82
-Doubling time: 25min
Anaerobic:
-pH: 5.6
-aw:.92
-Doubling time: 56 min

makes 3% of all food bourne illness

Question 4

char. staph aureus bacteria

Answer 4

• made up 239 amino acids
• its resistant to heat
• enteric toxin
• A, B,C, D, and F serotypes
• D55:
• D121:
• looks like a cluster of grapes

Question 5

Char. of staph aureus food bourne illness:

Answer 5

Onset: .5hours to 6hours
recovery: 24-72hours
major symptoms: vomiting and diareah
other symptoms: prostration, retching, nausea, and stomach cramps

Question 6

what are the toxic doses of staph aureus

Answer 6

• 10^5 cells per gram

- 1ng of toxin per gram

Question 7

Describe clostridium botulinum:

Answer 7

• Gram +
• rod shaped
• sporogenic
• A,B,C,D,E,F and G

Question 8

Human botulism in five forms

Answer 8

1. Wound-through injection
2. inhalation
3. infant-spores
4. Food bourne
5. Latrogenic-too much given during medical examination

Question 9

Describe the Mech. of Bont Intoxication:

Answer 9

Botulinum cell is ingested into a cell and thioredexin breaks disulphide bonds, releasing N-ethalmaide factor which breaks up snare proteins preventing the release of acetycholine causing paralysis.

Question 10

dosage of Clostridum Botulinum toxin to be effective?

Answer 10

• 3000ug will kill a 104kg person
• 300 ng to kill a 104 pound person
• 10^5-10^6(.1ng)-cultures produce

Question 11

How to kill clostridum botulinum

Answer 11

-Proteolytic heat resistant (spore forming): D121 degrees celsius- longer time
-Non proteolytic non heat resistant (spore forming): D121 degrees-shorter time
Toxin: kill by 100 degrees celsius

Question 12

What is botulism?

Answer 12

It’s an infection that is born in low acid canned food, poorly processed and preserved meat. It’s found eggs, pies, mushrooms and onions.

Question 13

Infant botulism

Answer 13

Spores germinate in the gut of a child and cause paralysis, sudden death and floppy head

Question 14

clostridium perferngins survival conditions

Answer 14

pH (mildly acidic to basic)
Neutral is preferred
Temp.
-cold-very hot
-0-53 degrees celsius
-optimum:43-47 degrees celsius (very hot)

Question 15

Clostridum perferengins characteristics:

Answer 15

-gram +
-tolerant towards o2
-encapsulated
-cannot move
-

Question 16

how do spores help c. perferngins survive?

Answer 16

-help it resist heat and refrigerated temperatures

Question 17

What is heat resistance of C. perferingins influenced by?

Answer 17

• environment

- genetics

Question 18

Whats the difference between plasmid CPE gene and chromosomal CPE gene

Answer 18

• Plasmid cpe gene-soil

- Chromosomal cpe gene- found in 1% of meat and fish

Question 19

How are CPE genes produced

Answer 19

Spooa gene is phosphorlated which activates the sig F gene to activate several other sig genes which lead to the activation of a CPE gene translating to a CPE protein.

Question 20

Char. of clostridium perferingins

Answer 20

onset: 8-72 hours(less than 1 day to 3 days)
recovery-1 day
symptoms-diareah and gas

Question 21

what is bacillius cereus?

Answer 21

• Metabolizes citrate
• aerobic
• gram +
• converts glycerol and sucrose into acid