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Microbiology > Host pathogens > Flashcards

Host pathogens Flashcards

1
Q

microbiota

A

the microorganisms that normally colonize various sites in/within the body without causing disease

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2
Q

resident microbiota

A

inhabit sites for extended periods

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3
Q

transient microbiota

A

inhibit temporarily for days, weeks, or months then disappear

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4
Q

colonization

A

ability of microbe to stay affixed to a body surface and replicate

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5
Q

what does our microbiota do

A

competitively exclude pathogens
- covering of binding sites prevents attachment
- consumption of available nutrients
- production of compounds toxic to other bacteria

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6
Q

how is microbiota acquired

A

humans are initially colonized by microorganisms at birth

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7
Q

what can perturb our microbiota

A

by age 3, a child’s microbiome looks a lot like an adult’s and it becomes much more stable

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8
Q

pathogen

A

any bacterium, virus, fungus, protozoan, or helminth that causes disease

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9
Q

pathogenicity

A

the ability of an organism to cause disease

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10
Q

true (primary) pathogens

A

can cause disease in a host regardless of the host’s resident microbiota or immune system
* are never part of the normal microbiota

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11
Q

opportunistic pathogens

A

cause disease only under opportunistic conditions
- changes in the composition of the normal microbiota
- can be members of normal microbiota or common in the environment

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12
Q

infection

A

successful colonization and multiplication of microorganism within a host with or without the manifestation of disease

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13
Q

infectious disease

A

illness caused by damage to host cells by an infectious agent or its products resulting in signs and symptoms

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14
Q

virulence

A

degree or severity of disease

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15
Q

lethal dose 50 (LD50)

A

the number of microbes that kills 50% of an experimental group of animal hosts

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16
Q

infectious dose 50 (ID50)

A

number of microbes that will cause infection in approximately 50% of an experimental group of hosts

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17
Q

stages of pathogenesis

A

exposure and entry
adhesion to skin or mucosa
invasion through epithelium and immune invasion
infection
toxins or host immune response
tissue damage, disease

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18
Q

fecal-oral portal of entry

A

through mucosal surfaces of gastrointestinal transportct

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19
Q

respiratory portal of entry

A

through musical surfaces of respiratory tract

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20
Q

transplacental portal of entry

A

through the placenta to infect a fetus

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21
Q

skin portal of entry

A

through epithelial surfaces

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22
Q

urogenital portal of entry

A

through mucosal surfaces of genital and urinary tracts

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23
Q

parenteral portal of entry

A

through injection into the bloodstream (for example, infect bites or needle sticks)

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24
Q

adhesion

A

fimbriae adhesions
cell wall adhesions
glycocalyzx (slime and capsular polysaccharides)

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25
Q

invasion

A

ability of some pathogens to spread through tissues
produce enzymes or toxins which serve as virulence factors that allow them to colonize and damage host tissues as they spread deeper into body

26
Q

immune evasion : antigenic variation

A

acquire changes in the genes for surface antigens that alter the structure of surface antigens that antibodies would otherwise recognize

27
Q

virulence factors for immune evasion

A

capsule
protease

28
Q

some bacteria resist phagocytic destruction by

A

preventing fusion of the lysosome with the phagosome
escaping from the phagosome before the lysosome fuses
preventing acidification of the phagosome
resisting killing by lysosomal chemicals

29
Q

exotoxins

A

proteins produced by pathogenic bacteria (gram positive and negative) and secreted

30
Q

endotoxins

A

lipid A portions of LPS that are part of the outer membrane of the cell wall of gram negative bacteria. they are liberated when the bacteria die and the cell wall breaks apart

31
Q

exotoxin mode of action: cytolytic toxins

A

work by disrupting the cytoplasmic membrane integrity, causing cell lysis and death

32
Q

exotoxin mode of action: AB toxins

A

consist of two subunits, A and B. B subunit binds host cell receptor and transfers subunit A across the cell membrane and this usually inhibits protein synthesis or disrupts ion homeostasis

33
Q

exotoxin mode of action : superantigen toxins

A

overactivate the immune system by activating non specifically CD4+ T cells which leads to an excessive cytokine release and excessive inflammatory response

34
Q

most genes for exotoxins are carried on

A

plasmids or phages

35
Q

body makes antibodies (anitoxins)

A

provide immunity

36
Q

inactivate exotoxin (heat, chemical)

A

toxoid vaccine to stimulate antibody production

37
Q

in an endotoxin ____ is the toxic part

A

lipid A

38
Q

endotoxins only come from gram _

A

negatie

39
Q

high/low dose of exotoxin

A

low

40
Q

high/low dose of endotoxin

A

high

41
Q

are exotoxins release actively or passively from bacteria

A

actively

42
Q

are endotoxins released actively or passively from bacteria

A

passively

43
Q

endemic

A

disease consistently present (often as low level) in a population

44
Q

sporadic

A

when occasional cases are reported as irregular intervals

45
Q

epidemic

A

occurrence of more cases of disease then expected in a given area over a particular period of time

46
Q

pandemic

A

an epidemic occurring on several continents and usually affecting an exceptionally high proportion of the global population

47
Q

prevalence

A

number of existing cases of disease in a population during a defined period of time
- how much of a population is affected

48
Q

incidence

A

number of new cases of disease that vela in a population during a defined period of time
- how quickly are people becoming infected

49
Q

mortality rate

A

incidence of death due to a disease during a particular time period

50
Q

case fatality rate

A

mortality rate / incidence rate

51
Q

infectious disease

A

may or may not be communicable

52
Q

communicable disease

A

an infectious disease that is contagious and which can be transmitted from one infected host to another

53
Q

period of disease

A

incubation period
prodromal period
period of illness
period of decline
period of convalescence

54
Q

droplet transmission

A

close range (within 3 feet)

55
Q

fomites

A

inanimate objects that transmit pathogens

56
Q

droplet nuclei

A

inhaled by those over a long distance

57
Q

zoonoses

A

when a disease comes from animals

58
Q

acute disease

A

symptoms develop rapidly

59
Q

chronic disease

A

symptoms develop gradually over months or years of lifetime and are slow to resolve

60
Q

latent disease

A

the causal pathogen goes dormant for extended periods of time with no active replication. no symptoms unless organism reactivates and infection again becomes acute

Microbiology (11 decks)

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