Unit 2- Determinants of Pathogenicity Flashcards Preview

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Flashcards in Unit 2- Determinants of Pathogenicity Deck (35):
1

What is a niche

a compartment with unique properties (ie. temperature, pH, nutrients)

2

What proportion of body cells do microbes make up?

90%

3

When do microbes start colonizing the human body

at birth and throughout lifetime

4

What is commensalism?

One organism benefiting without harming the other

5

What is mutualism?

Two organisms cooperating to both benefit (ie. bacteria in the grass cows eat help the cow digest grass)

6

What is parasitism?

One organism benefiting at the expense of another (harm is done to one)

7

How long does colonization of a baby take after birth?

8-12 hours

8

What protects the womb from vaginal microbes?

Fetal membranes

9

What microbes are exposed to bottle-fed babies?

coliforms, lactobacilli, enteric strepotococci, staphylococci

10

What microbes are exposed to breast-fed babies?

bifidobacterium

11

Where in the body do normal flora microbes colonize?

Skin, mucous membranes, upper respiratory tract, gastrointestinal tract, outer opening of urethra, external genitalia, vagina, external ear and canal, external eye (lids, lash follicles)

12

What are microbes that are temporary in the body called

Transients

13

What are long term/permanent microbes called?

Residents

14

Pathogen?

Parasitic microbes with the potential to cause disease

15

What a true/primary pathogens?

Those likely to cause disease in people with normal immune system

16

What are opportunistic pathogens?

They cause disease in immunocompromised people

17

What factors weaken host defenses and increase susceptibility to infection?

Old age, extreme youth, genetic defects or acquired defects in immunity, surgery and organ transplants, organic disease (liver, cancer, diabetes), chemotherapy/immunosuppressive drugs, physical and mental stress and other infections

18

Invasion?

Microbes enter into germ-free tissues or cells

19

Infection

Microbe spreads throughout the tissues and body

20

Virulence

degree of harm caused by pathogen

21

virulence factors

Intrinsic characteristics of pathogens that contribute to virulence

22

infectious dose (ID)

minimum number of microbes required to cause illness

23

lethal dose (LD)

minimum number of microbes needed to cause death

24

Virulence factors of E. coli?

1) toxins to break down gut lining 2) rapid growth 3) ability to enter gut lining (ingesting as little as 10 cells may cause illness)

25

Virulence factors of Vibrio cholera

1) produces cholera toxin (which draws salts and water into intestine, causing diarrhea) (ingesting 10^6-10^11 cells are needed to cause illness)

26

ID50?

minimum amount of microbes required to infect 50% of a given population

27

LD50

amoutn of microbes needed to kill 50% of a given population

28

the ____the ID50 and LD50, the more virulent the pathogen

lower

29

Adhesion?

adsorption to host cells and tissues

30

Adhesion mechanisms of bacteria

Fimbrae (non-specific), capsule

31

Adhesion mechanisms of viruses

Glycoproteins (specific), Hemagglutinin (non-specific)

32

Evasion?

Antiphagocytic factor, prevent being eaten from immune cell

33

3 strategies to avoid phagocytosis?

1) Capsule- slimy layer preventing phagocytosis
2) Toxins- defense against phagocytic cells
3) Leukocidins- toxins that directly kill WBCs

34

Intracellular Microbes do what?

hide inside host cells, and ecrete molecules into a target cell to make it easier to enter

35

Evasive factors of H. pylori?

1) urease produces NH4 to neutralize stomach acid
2) flagella