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Flashcards in Introduction to Pathogens Deck (111):
1

microbiota

normal flora
part of the innate immunity

do not cause disease (do some good)

commensalists or mutualists

2

how much does normal flora weigh?

5-10 pounds

1/3 in feces

also lots on skin

3

commensalism

neither harm or benefit the carrying host

4

mutualism

symbioitic relationship between two organisms where both benefit

5

benefits of flora?

produce Vit K
absorb nutrients
secrete bacteriocins

6

bacteriocins

released by normal flora to kill other bacteria

7

harm of flora

can be come pathogenic outside of normal niche

8

penicillinase bacteria

can interfere with therapy
breaks down penicillin

9

opportunistic pathogens?

normal flora outside of normal location can cause problems

10

streptococcus viridans

in mouth

can get to heart during dental procedures and results in infections endocarditis

11

three types of microbiota?

resident, transient, colonzation

12

resident normal flora?

costant and well defined

role in interference
-compete for binding site, nutrients, and create metabolic/toxic products and bacteriocidins

13

transient normal flora?

from travel

exposure to abnormal environment

14

colonization?

establishment of microbial population

acquisition of a new organism

15

flora in utero?

we are sterile

develop flora through birth canal, breast feeding, bottle feeding

facultative flora - acquired from oral exposure to feces

strict anaerobes can colonize only after sufficient facultative organisms are established enough that oxygen concentration are maintained at reduced levels

16

two basic mechanisms of pathogens?

invasion of tissue
production of toxins

17

invasiveness

ability to invade host tissues

18

different ways to invade host tissue?

capsule
adaptations
extracellular enzymes that degrade host tissues

19

virulence

combination of invasiveness and toxigenicity

20

LD50

percent dead vs. dose

measure of virulence

dose to kill half populationID50

21

communicability

transmission of infectious disease

22

factors involved in the communicability of a disease?

source (both dormant and latent)
number of agents released by host
capability of surviving the transit (host to host)
percent of host susceptible to agent
ID50 - infected vs. dose

23

ID50

infected vs. dose

dose require to infect half population

24

toxigenicity

production of toxins

25

exotoxins

secreted protieins
are heat labile
found mostly in gram-positive

26

what is found in gram-positive cells?

exotoxins

27

endotoxins

complex polysaccharides (LPS) that are part of bacterial cell wall
-released when cell lysis occur

generally heat stable

in gram negative found

28

what is found in gram-negative cells?

endotoxins

29

pathogenic process?

adhere
evade local immunity
replicate
evade systemic immunity
must escape body for transmission to new host

30

intracellular pathogens produce?

chronic disease

31

extracellular pathogens produce?

acute disease

32

what are the stages of infection?

incubation
prodrome (non-specific symptoms)
specific-illness (have characteristic signs/symptoms)
recovery
latent

33

prodrome period

stage of infection

where you have non-specific illnesses

34

viruses

are parasites

obligate intracellular parasites

may be either DNA or RNA (single or double stranded)

surrounded by protein capsid

some viruses have envelope
-from host cell

35

virus replication

must attach to host cell
bunch of shit happens.

36

non-enveloped virus entry to cell?

pinocytosis

37

enveloped virus entry to cell?

fusion

38

abortive infections

virus infects a cell that doesn't permit its replication

39

cytolytic infection

viral infection leading to cell lysis

40

persistent infections

viral infection that my be productive, latent, or transforming

41

rhinovirus

most common viral infective agent
-common cold

42

two modes of transmission for rhinovirus?

aerosol of respiratory droplets
contaminated surface

43

rhinovirus structure

single strand positive sense RNA and capsid

no envelope

44

viral proteins of rhinovirus?

proteins transcribed as single, long polypeptide and cleaved into structural and nonstructural viral proteins

45

bacteria

unicellular prokaryote microorganisms

46

bacterial cell wall

basis for classifaction

47

gram positive bacteria

thick layer of peptidoglycan on surface

also have lipotechoic acids (only gram +)

48

peptidoglycan

polymer of N-acetylmuramic acid and N-acetylglucosamine

49

gram-negative bacteria

thin peptidoglycan located between cytoplasmic and second outer membrane (periplasmic space)

have lipopolysaccharide in outer membrane

also have lipid A

50

gram-negative staining?

appear red

51

cocci

spherical bacteria

52

bacilli

rod-like bacteria

53

spirochetes

corkscrew bacteria

54

flagella

bacterial structure allowing for motility

-composed of flagellins that are also immunogenic

55

monotrichous

single polar flagella

56

lophotrichous

several polar flagella

57

amphitrichous

several flagella at each end

58

peritrichous

flagella cover entire surface

59

pili

bacterial appendage that are sort

sex pili and common pili

60

sex pili

involved in conjugation and transfer of genetic information from one cell to another

61

common pili

provides means for attachment to host cells and often play an important role in colonization

62

bacteria transmission

many require human to human

some can survive in environment

63

endospore

resistant to heat, radiation, drying

dormancy for hundreds of years WOWZA

64

capsules

bacterial structure with high MW polysaccharide

65

capsule

strongly adhered to cell wall

genetically and phenotypically controlled

66

slime layer

loosely associated with bacteria

67

aerobic bacteria

require oxygen

68

anaerobic bacteria

energy from fermentation
oxygen can be poisonous to these bacteria

69

facultative anaerobes

grow under aerobic conditions and can also ferment

70

clostridium difficile

gram positive, rod-shaped, spore former
obligate anaerobe
part of normal flora

has toxin A - enterotoxin - fluid accumulation
also toxin B - cytopathic agent

patient secretes large number of spores

can't compete with normal intestinal flora

71

toxin A in c. dificile?

fluid accumulation - diarrhea

72

toxin B in c. dificile?

cytopathic agent

73

fungi

either yeast or mold

74

yeast

single cell fungi (oval or round)

75

mold

long filamentous fungi

forms a mat (mycelium)

76

thermally dimorphic fungi

change from mold to yeast depending on temperature

ambient temperature - mold
in host tissues - yeast

77

candida

yeast at ambient temp and mold in host tissue

**exception to most thermally dimorphic fungi

78

fungi metabolism?

most are aerobes

some facultative anaerobes

**no strict anaerobes

requires carbon source

79

cell wall of fungi?

has chitin

also ergosterol and zymosterol

80

ergosterol and zymosterol

in cell membrane of fungi

81

chitin

in cell wall of fungi

82

superficial mycoses

dead layers of skin/hair - mostly cosmetic

not major harm

83

subQ mycoses

get into deeper layers

can often remember trauma
single location
from environment

84

cutaueous mycoses

epidermis, hair, nails

not doing lots of harm

85

systemic or deep mycoses

internal organs

immunocompromised host
-not a good prognosis
no human-human transmission
dependent on geographic niche

most are sub-clinical

86

mycoses

fungal infection

87

candida albicans

part of natural flora
fungi

both yeast and mold

opportunistic in immunocompromised individuals

88

thrush and vaginitis?

candida albicans superficially

89

candidemia

aka fungemia
systemic fungal infection of candida albicans

90

parasite

one organism harms the other

91

protozoan

single cell parasite with membrane bound nucleus

92

metazoans

multicellular parasite
-worms

93

arthropods

parasite insects
ex/ lice

94

host

organism where parasite obtains nutrients

95

definitive host

where parasite reaches sexual maturity

96

intermediate host

where parasite passes through larval or asexual stages

97

accidental host

other than normal host

98

reservoir host

other than the normal host in which parasite is capable of living and serving as a source of infestation

get rid of reservoir, get rid of parasite

99

vector

carrier that transmits causative agent of disease from infected to non-infected

100

modes of transmission for parasites?

direct
-ingestion, skin penetration, inhalation, person-to-person

indirect
-vector, transplantation/transfusions

101

single-host parasites

human to human contact

oral-fecal T vaginalis and E. histolytica

102

multiple host parasites

require two or more hosts to complete life cycle

can be limited to geographical area

103

what causes more disease and misery than any other group of agents?

protozoa

according to WHO

104

protozoans

eukaryotic
large variation in size
true nucleus and cytoplasm

105

trophozoites

active form of protozoa (fragile)

106

cyst

dormant form of protozoa (resilient)

107

nematodes

round worms
tough outer cuticle (what eosinophils break down)

have separate organ systems and sexes
intestinal tract and blood

108

soil-transmitted helminthiasis

STH

ascaris, necator, ancylostoma, trichuris

in 5-14 year old age range

all cause nutritional impairment leading to cognitive impairment

109

platyheliminthes

tape worms
flatted ribbon shaped bodies

proglottids - generated by neck

110

proglottids

egg of platyhelminthes that is secreted in fecal matter

neck generates the proglottids

111

FMT

fecal matter transplant

treats c. dificile non-responsive to standard therapy (vancomycin)