Chapter 11: Interactions between Humans and Microbes Flashcards Preview

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Flashcards in Chapter 11: Interactions between Humans and Microbes Deck (105)
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1

Infectious Disease

the disruption of a tissue or organism caused by microbes or their products

2

Do all contacts lead to colonization and then to infection and then to disease?

Not all contacts lead to colonization; Not all colonizations lead to infection and Not all infections lead to disease

3

Normal (Resident) Biota

microbes that live peacefully and symbiotically in the human body; include an array of bacteria, fungi, protozoa, viruses, and arthropods

4

Human Microbiome Project

will identify genetic sequences to determine which microbes are inside and on humans, even though they can’t be cultured in the laboratory; will determine what the normal biota play in human health and disease; uses metagenomics

5

These general parts of the body are microbe free:

Internal organs, tissue, and their fluids

6

Sites that harbor normal biota (8)

(1) Skin and its adjacent mucous membranes; (2) Respiratory tract; (3) GI Tract (various parts); (4) Outer opening of the urethra; (5) External genitalia; (6) Vagina; (7) External ear canal; (8) External eye

7

Factors that weaken host defenses and increase susceptibility to infection (4)

(1) Old age and extreme youth; (2) Genetic and acquired defects in immunity; (3) surgery and organ transplants; (4) Underlying disease

8

Why are normal biota unlikely to be displaced by other microbes?

(1) Limited number of attachment sites; (2) Chemical and physiological environment created by normal biota is hostile to others

9

Vaginally delivered baby has been colonized by these microbes (3)

streptococci, staphylococci, and lactobacilli

10

These bacteria colonize the large intestine of bottle-fed infants:

coliforms, lactobacilli, enteric streptococci, staphylococci

11

Bifidobacterium

Breast-fed infants receive this bacterium because it favors the growth factor in milk; metabolizes sugars into acids to protect the infant from intestinal pathogens

12

Which of the following body sites is not colonized by known normal biota?

A. skin and mucous membranes
B. external genitalia
C. gastrointestinal tract
D. kidneys and bladder
E. respiratory tract

D. Kidneys and bladder (internal organ)

13

Pathogenicity

an organism’s potential to cause infection or disease

14

A true pathogen is capable of...

causing disease in a healthy person with normal immune defenses

15

Opportunistic Pathogen

cause disease when the host’s defenses are compromised or when they become established in a part of the body that is not natural to them; Not pathogenic to a normal, healthy person

16

Examples of opportunistic pathogens (2)

Pseudomonas species; Candida albicans

17

Virulence

determined by its ability to establish itself in a host & cause damage (not the same as pathogenicity)

18

Virulence Factor

any characteristic or structure of the microbe contributes to its ability to establish itself in the host and cause damage

19

Portal of Entry

the route that a microbe takes to enter the tissues of the body to initiate an infection

20

Exogenous

microbe originating from a source outside the body from the environment or another person or animal

21

Endogenous

microbe already existing on or in the body – normal biota or a previously silent infection

22

Infectious agents that can enter through more than one portal of entry (3)

(1) Mycobacterium tuberculosis can enter through both the respiratory and gastrointestinal tracts; (2) Streptococcus and (3) Staphylococcus can enter through the skin, urogenital tract, and the respiratory tract

23

Infectious Dose (ID)

the minimum number of microbes necessary to cause an infection to proceed; smaller ID = higher virulence

24

ID for Rickettsia

single cell

25

ID for tuberculosis, giardiasis, and coccidioidomycosis

10 cells

26

ID for gonorrhea

1,000 cells

27

ID for typhoid fever

10,000 cells

28

ID for cholera

1,000,000,000 cells

29

Adhesion

process by which microbes gain a more stable foothold on host tissues; firm attachment is imperative for causing infection

30

Adhesion Mechanisms (4)

(1) fimbriae (pili), (2) surface proteins, (3) adhesive slimes or capsules, (4) specialized receptors