3-Host Bacterial Relations Flashcards

1
Q

symbiosis

A

intimate and prolonged associated b/t 2+ orgs of diff species
-commensalism, mutualism, parasitism

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2
Q

normal microbiota

flora

A

community of microbes that live in/on indiv

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3
Q

niche

A

shelter physcial space, food for others

that plays a role in microbial community

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4
Q

microbiome

A

aggregate collection of genes/genomes from microbiota

can tell you what a microbiota is doing

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5
Q

pre vs pro biotics

A

prebiotic = food ingredient that supports growth of 1+ members of microbiota

probiotics= live microbes ingested to benefit host, debatable

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6
Q

where is microbiota at

A

conflicting bc not able to culture well
-seq prone to contamination (16S)

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7
Q

loose rules of microbiota location

A
  1. any site exposed to environ, if not direct link to outside then not normal microbiota
    -sterile anatomic sites

placenta, fetus, middle ear debatable

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8
Q

resident microbiota

A

long term
part of noraml microbiota

staphylococcus epidermidis @skin and nares

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9
Q

transient microbiota

A

microbes that attempt to colonize but fail

streptococcus pyogenes @oropharynx

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10
Q

factors that affect microbiome

A
  1. mode of delivery neonate
  2. host genetics
  3. host immune resp
  4. diet
  5. xenobiotics (antibiotics)
  6. infectinos
  7. diurnal rhythm
  8. environment exposures
  9. age
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11
Q

microbiota development

A
  1. fetus- sterile
  2. neonate- colonized by vaginal bacteria or rapidly colonzied after birth c section
  3. childhood- change early (breastmilk) then stable late childhood
  4. healthy adult- stable
  5. elderly- inc susceptibilty to infection from microbiota

aka changes as we age

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12
Q

intestinal microbita functions

A
  1. biosynthesis- vitamins, hormones, neurotrans
  2. metabolism- diet, bile salts, drugs
  3. influence-homeostasis, host cell prolif, bone density, neurologic signaling
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13
Q

how intestinal microbiota protects from infection

A
  1. occupy niches to prvent colonization/access to host tissue
  2. primes innate immunity by stim mucin, IgA
  3. promote epi cell resistance and low level inflamm
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14
Q

strict pathogens

A

orgs that are always associated with disease

myobacterium tuberculosis
neisseria gonorrhoeae
rabies virus

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15
Q

opportunistic pathogens

A

members of normal mb that take advantage of condtiions to cause disease

E. coli from intestines to urinary tract

most infectious diseases caused by

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16
Q

pathogenicity

A

ability of microorg to cause disease

virulence is measure of pathogenicty

17
Q

virulence factors

A

enable
-colonization
-immune evasion
-entry/survival within host cells
-obtain nutrients to survive in host

18
Q

entry into host mechanism

A
  1. transplacental
  2. secretions
  3. stool -oral
  4. skin
  5. blood
  6. zoonotic
  7. arthropod
19
Q

barriers to entry

A
  1. mechanical
  2. enzymes
  3. chemicals
  4. immunity
  5. commensals
  6. physical
20
Q

adherence

A

first step
binds to host cell surface via adhesin proteins with pili (often not always)

21
Q

biofilms

A

bacteria encased in exopolymeric substance to adhere to surface and stay stationary
-found on moist/wet surface

22
Q

biofilm characteristics

A

-slower metabolism than free floating planktonic
-inc resist to antibiotics
-inc genetic exchange
-resistant to disinfection

23
Q

pathogenic action

A

after adhered and colonzied
1. toxin production
2. invade cells, or
3. disseminate
4. tissue destruction
5. endotoxins- lipid A of LPS
6. exotoxins- cytolytic enz, toxic rxns

24
Q

AB toxins

A

A = active
B = binding

type of exotoxin- direct tissue damage, destructive

25
superantigens
bind both TCR and MHCII without an antigen so get cytokine storm S. aureus TSST1, Staph. enterotoxin, S. pyogenes erythrogenic toxins
26
mechanisms for evading
1. antigenic masking by capsule 2. mimicry- make host see as self 3. shift/variation- change proteins on cell surface so moving target for immune system 4. resist complement 5. inactivate antibody via proteases
27
how to escape phagocytic clearance
1. inhib opsonization 2. inhib chemotaxis 3. kill phagocyte 4. inhib
28
intravenous catheter contamination | opportunistic
1. staphylococcus epidermidis (skin) 2. sstaphylococcus aureus (skin)
29
wound surgical site infection | opportunistic
1. staphylococcus aureus - skin 2. klebsiella pneumoniae- intestine 3. pseudomonas aeruginosa- skin
30
tooth decay/dental caries
streptococcus mutans - teeth
31
urinary tract infections
escherichia coli-intestine E.coli
32
pseudomembrane colitis
1. clostridiodes difficile- intestine, from antibiotic therapy spores that survive and overgrow
33
otitis media
middle ear infection 1. streptococcus pneumoniae 2. non typeable haemophilus influenzae 3. moraxella catarrhalis - nasopharynx
34
what's NOT virulence factor
1. peptidoglycan 2. factors in metabolism required for survival outside host aka core metabolism proteins 3. chromosome 4. membranes 5. ribosomes