Chapter 1.2 Cell Structures, Virulence Factors And Toxins

Question 1

What is the virulence of an organism?

Answer 1

Degree of organism pathogenicity

Question 2

What does virulence depend on?

Answer 2

Presence of certain cell structures and on bacterial exotoxins and endotoxins (which are all virulence factors)

Question 3

What are the 2 tests used by doctors or visualize capsules under a microscope to help identify bacteria?

Answer 3

India ink stain and Quellung Reation

Question 4

What is the India Ink Stain?

Answer 4

This stain is not taken up by the capsule and the capsule appears as a transparent halo around the cell

Question 5

What fungus uses primarily the India ink stain?

Answer 5

Crytococcus

Question 6

What is the Quellung reaction?

Answer 6

When bacteria are mixed with antibodies that bind to the capsule causing the capsule to swell with water

Question 7

How does the vaccine for Stretococcus pneumoniae work?

Answer 7

The vaccine contains antigens from the 23 most common capsules
A immune response is elicited against the capsular antigens
Production of antibodies that protects the individual against future infections of this organism

Question 8

What are endospores?

Answer 8

Metabolically dormant forms of bacteria that are resistant to heat, cold, drying, and chemical agents

Question 9

What are the 2 genera of bacteria that have endospores?

Answer 9

2 gram-positive bacteria: aerobic Bacillus and the anaerobic Clostridium

Question 10

What is a plasmid?

Answer 10

Small adjacent circles of double-stranded DNA

*are often antibiotic resistant

Question 11

What is special about bacteria that have endospores?

Answer 11

They are safe from antibodies and other immune defenses

Question 12

When do spores form?

Answer 12

When there is a shortage of needed nutrients and can lie dormant for years

Question 13

What is the mechanism of a facultative intracellular organism?

Answer 13

Inhibit phagosome-lysosomes fusion and escape the hydrogen peroxide and superoxide radials

Question 14

What are exotoxins?

Answer 14

Proteins released by both gram-negative and gram-positive bacteria

Question 15

What gram-positive bacteria does NOT release exotoxins?

Answer 15

Listeria monocytogenes (induces endotoxin instead)

Question 16

What are 2 examples of gram-negative cells that secrete exotoxins?

Answer 16

Vibrio cholera

E. Coli

Question 17

What diseases can be caused by bacterial exotoxins?

Answer 17

Anthrax, botulinum, tetanus, and cholera

Question 18

What are enterotoxins?

Answer 18

Exotoxins that act on the GI tract to cause diarrhea

Question 19

What is the end mechanism of enterotoxins?

Answer 19

Osmotic pull of fluid into the intestine which causes diarrhea

Question 20

What disease manifestations are caused by enterotoxins?

Answer 20

Infectious diarrhea and food poisoning

Question 21

How does infectious diarrhea occur by enterotoxins?

Answer 21

Bacteria colonize and bind to GI tract and continually release enterotoxins
Diarrhea will continue until the bacteria are destroyed by immune system or antibiotics

Question 22

What are examples of bacteria that cause infectious diarrhea?

Answer 22

Vibrio cholera, E. Coli, Campylobacter jejuni, and Shigella dysenteriae

Question 23

How does food poisoning occur by enterotoxins?

Answer 23

Bacteria grow in food and release enterotoxins in the food

The enterotoxin is ingested resulting in diarrhea and vomiting for less than 24 hours

Question 24

What are examples of bacteria that cause food poisoning?

Answer 24

Bacillus cereus

Staphylococcus aureus

Question 25

What are pyrogenic exotoxins?

Answer 25

Exotoxins that stimulate the release of cytokines

Question 26

What are the manifestations from a pyrogenic exotoxin?

Answer 26

Rash, fever, toxic shock syndrome

Question 27

What are examples bacteria that release of pyrogenic exotoxins?

Answer 27

Staphylococcus aureus and Streptococcus pyogenes

Question 28

What are tissue invasive exotoxins?

Answer 28

Exotoxins that allow bacteria to destroy and tunnel through tissues

Question 29

How does endotoxin differ from exotoxin?

Answer 29

Endotoxin is not a protein exerted from cells but a normal part of the outer membrane that sheds off, especially during lysis

Question 30

What bacteria is endotoxin present in?

Answer 30

ONLY gram-negative bacteria with one exception: Listeria monocytogenes
*Listeria monocytogenes is the only gram-positive bacteria that has endotoxin

Question 31

What is septic shock?

Answer 31

Deadly response to gram-positive and gram-negative infections

Question 32

What is bacteremia?

Answer 32

Bacteria in the blood-stream and can be detected in blood culture
Can trigger immune system and result in sepsis and possibly death

Question 33

What is sepsis?

Answer 33

Bacteremia that a uses a systemic immune response to the infection

Question 34

What can be the symptoms of sepsis?

Answer 34

High or low temperature, elevation of the white blood cell count, fast heart rate or breathing rate.

Question 35

What are the symptoms of septic shock?

Answer 35

Dangerous drop in blood pressure and organ dysfunction

Question 36

What is the most famous endogenous mediator of sepsis?

Answer 36

TNF (also called cachectin)

Question 37

What does TNF do during sepsis?

Answer 37

Triggers releases of IL-1 from macrophages and endothelial cells

Question 38

What do the mediators cause during sepsis?

Answer 38

Vasodilation, hypotension, and organ system dysfunction

Question 39

Where is the most common site for bacteria?

Answer 39

Respiratory system

Question 40

What is the most common bacteria in the lung?

Answer 40

Pneumonia

Question 41

What is the “fire early and hit everything” concept?

Answer 41

If a patient looks like they are going into septic shock- give them all the antibiotics to try and fight everything
*make sure to culture before giving them antibiotics because after you won’t have any to culture

Question 42

What is used to block inflammation during septic shock?

Answer 42

TNF, IL-1, and anti-inflammatory agents (ibuprofen and steroids)