1-11 Commensalism vs. Pathology Flashcards Preview

MSI Unit I > 1-11 Commensalism vs. Pathology > Flashcards

Flashcards in 1-11 Commensalism vs. Pathology Deck (30):
1

Define:
Mutualism
Commensalism
Parasitism

Mutualism (symbiosis): organism 1 (initiates interaction) benefits, organism 2 ALSO benefits

Commensalism: organism 1 benefits, organism 2 neither benefits nor is harmed.

Parasitism (in micro, pathogenesis): Organism 1 benefits, organism 2 is HARMED

2

Describe the condition under which a commensal microorganism can become a pathogen

Many commensal microorganisms are opportunistic pathogens, and can become pathogenic when they are in the wrong part of the body (out of their appropriate “container”), when the host is immunocompromised, or when the population balance among commensals is disrupted (e.g. due to antibiotic exposure).

3

Define normal flora

The normal flora are bacteria which are found in or on our bodies on a semi-permanent basis without causing disease
Human normal flora is mostly commensal.

4

Name two commensal microorganisms common in each system:
Gastrointestinal
Respiratory
Reproductive
Skin

Gastrointestinal System– Clostridium difficile, Escherichia coli

Respiratory System – Streptococcus pyogenes, Staphylococcus aureus

Reproductive System- Candida albicans, Lactobacillus acidophilus

Skin – Staphylococcus epidermidis

5

Define colony resistance and explain how it serves as an element of innate immunity

Colonization resistance is the process by which commensal bacteria help to prevent the colonization of foreign bacteria.
It is anti-pathogenic and nonspecific, and thusly is an important element in the nonspecific innate immunity.

6

Define ID50 and LD50

ID50 – The dosage needed to infect half of the host cells (used to determine how much is needed to cause disease).

LD50 – The dosage needed to kill half of the host cells (used to determine how much is needed to kill the host).

7

Define:
Obligate Intracellular Parasites
Facultative Intracellular Parasites

Obligate Intracellular Parasites – Parasites that can only propagate by using a cellular host.

Facultative Intracellular Parasites – Parasites that can propagate without a cellular host when necessary.

8

What are the 5 major activities of virulence factors?

1. Survival in extreme environments
2. adhesion
3. immune evasion
4. host cell takeover
5. poisoning host

9

What are Types 3 & 4 secretion systems?

Used for host cell takeover
Type 3: injects toxin "injectosome"
Type 4: comparable but able to transport DNA in addition to proteins

10

Recite Koch's Postulates

1. Observe potential pathogen of sick animal
2. Grow a pure culture of pathogen
3. Infect a new animal from the culture (this is not done at a usual office visit)
4. Observe same disease in new animal
5. Culture the same potential pathogen from the new animal
If fulfilled, can say with certainty that the pathogen causes disease

11

What are exotoxins?

Involved in "poisoning of host" virulence factor. These are polypeptides secreted from the pathogen or injected into host cell by T3SS.
Common activities may include: profound toxicity may result from superantigenicity, interference with signal transduction, depolymerization of actin, or other acitvities

12

What the function of each subunit in A-B subunit structure?

A unit is the active toxic activity
B unit binds the host cell to deliver A

13

What is heat- or chemically inactivated exotoxin called?
What can this be used for?

Toxoid...useful as a vaccine

14

Are previous exposure or vaccination protective against endotoxins?

No-endotoxins are intrinsic to the surface of bacteria, cause immunogenic symptoms, and neither previous exposure NOR vaccination are protective against endotoxins

15

Endotoxin are cell wall components of which type of bacteria? (Gram+/-) and what is an example of one?

Gram -

LPS

16

which are more toxic, endo or exo toxins?
-

exotoxins are more toxic

17

which type of toxin is more heat stable?

endotoxcins are more heat stable

18

what type of toxins are part of the bacterial cell wall?

endotoxins

19

which type of toxin binds to specific cell receptors?

both endo and exo.

20

main defense against exotoxins

IgG and IgM antibodies

21

bacteriodis fragilis?

colon

22

straph aureus

nose

23

what best describes the endotoxin mode of action

causes release of tumor necrosis factor cytokine

24

serologic tests are based on antigen presence. which is least likely to give useful antigens? capsule, flagella, exotoxins, ribosomes

ribosomes

25

3 effects of exotoxin

fever, coagulation cascade initiation, hypotension

26

the toxicity of endotoxins is due to what portion of molecule?

lipid portion

27

the antigenicity of somatic (O) antigen is due to

repeating oligosaccharides

28

exotoxins are

polypeptides

29

exotoxins are less toxic than the same amount of endotoxins, TF

false.

30

what contributes to dental caries?

step mutans

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