Bacteria Chapter 22-18-19 Helicobacter- Pseudomonas - Bordetella - Corynebacterium Flashcards

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1
Q

describe helicobacter pylori

A
  • gram negative vibrio
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2
Q

what chemical reaction does helicobacter pylori cause

A

urea + H2O -> CO2 + ammonia

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3
Q

what are the virulence factors for helicobacter pylori and what do they do

A

-urease: urea-> ammonia -> pH increase, neutralization of stomach acid
- VacA: protein that acts on gastric mucosal epithelia and promotes flow of urea into stomach
- CagA: protein injected into host epithelia -> cells change
- mucinase
- flagella

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4
Q

how do organisms survive the acidity of stomach juices

A

by producing a powerful urease
- upon reaching the layer of mucus they penetrate to the epithelial surface where bacterial products incite an inflammatory response
- thinning of mucus layer occurs and 10 to 20% of infected individuals develop ulcerations
- only small percentage develop cancer but more than 90% of individuals with stomach cancers are infected with H pylori

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5
Q

how are gastric ulcers treated

A
  • no preventative
  • 2 antibiotics plus a medication to suppress stomach acid
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6
Q

what is the initial infection immune response of gastric ulcers

A

IgM followed by IgA and IgG which suppresses bacterial growth and leads to the typical low level persistent infection which remains symptom free for 80-90% of carriers

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7
Q

what are the symptoms of helicobacter pylori

A

no symptoms in most people

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8
Q

describe pseudomonas aeruginosa

A

gram negative rods
- polar flagella
- obligate aerobe
- simple nutrient requirements
- broad temperature range 20-43 Celcius

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9
Q

how are pseudomonas aeruginosa cells arranged

A

pairs

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10
Q

what are the virulence factors for pseudomonas aeruginosa

A
  • alginate: adherence, protection from dehydration and immune evasion
  • lipopolysaccharide: lipid A is endotoxic; core interacts CFTR; O antigen protects from complement- mediated killing
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11
Q

what is alginate’s possible contribution to virulence

A

biofilm formation

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12
Q

describe opportunistic pathogens

A

-common in environment
- resistance to many chemical disinfectants
- R-plasmid based resistance to many antibiotics

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13
Q

what types of pathogens are major problems in hospitals

A

opportunistic pathogens in nosocomial infections

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14
Q

where are opportunistic pathogens seen in hospitals

A
  • lungs: artifical ventilators, cystic fibrosis
  • skin: burn victims, folliculitis
  • bladder infections
  • ear infections
  • eye infections
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15
Q

what characterizes pseudomonas aeruginosa

A

soluble blue green dye pyocyanin and pyoverdin

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16
Q

describe the clinical features and epidemiology for pseudomonas aeruginosa

A
  • pulmonary (CF patients)
  • nosocomial infection
17
Q

what are the antibiotic resistance mechansisms for penicillins, aminoglycosides, chloramphenicol, fluoroquinolones

A
  • penicillins: beta lactamase, altered binding or uptake
  • aminoglycosides: hydrolysis, altered uptake
  • chloramphenicol: hydrolysis, altered uptake
  • fluoroquinolones: change in DNA gyrase, altered uptake
18
Q

describe bordetella pertussis

A

gram negative
- strict aerobe
- non motile, capsule

19
Q

what illness is caused by bordetella pertussis

A

whooping cough

20
Q

what does Bordetella pertussis show

A

dense surface growth in the lower respiratory tract (bronchi and bronchioli) without cell invasion and with strong mucus secretion

21
Q

what is the virulence factors in whooping cough

A
  • adhesion to ciliated respiratory tract cells but NOT invasive
  • toxins
22
Q

what toxins are virulence factors for pertussis

A
  • pertussis toxin ptx
  • secreted invasive adenylate cyclase/hemolysin
  • tracheal cytotoxin: NO release
23
Q

what does pertussis toxin ptx do

A

ADP-ribosylation of G protein: cAMP increase -> increase mucus and other secretions

24
Q

what does secreted invasive adenylate cyclase/hemolysin do

A

increase cAMP

25
Q

what does tracheal cytotoxin do

A

-NO release
- kills ciliated cells
-toxin is a component of peptidoglycan

26
Q

what is the bordetella pertussis treatment and epidemiology

A
  • DTaP vaccine
  • aerosol transmission, children’s disease, mild symptoms in adults who are the resevoir
27
Q

describe corynebacterium diptheriae

A
  • gram positive pleiomorphic rods
  • opportunistic pathogen
  • oral pathogen with systemic effects
28
Q

what are the characteristics of diptheria and mechanism of action

A
  • pseudomembrane in the throat, heart, kidney damage
  • inhibits protein synthesis by inactivation an elongation factor of eukaryotic cells. kills local cells in the throat but can also be carried in the bloodstream to various organs
29
Q

what chemical reaction is caused by diptheria

A

NAD + EF2 -> ADP ribose EF2 + nicotinamide

30
Q

what are the virulence factors for diptheria

A

-throat adhesion
- diptheria toxin (ADP ribosylation of EF2 causing translation to stop)

31
Q

what are local and systemic disease risks from diptheria toxin

A

local: suffocation and paralysis - impaired swallowing, peripheral neuritis
systemic: cardiac arrhythmia and kidney failure

32
Q

what is the treatment and epidemiology for diptheria toxin

A
  • prevent by toxoid vaccination
  • spread by saliva droplets
33
Q

what illnesses does the DPT vaccine protect against

A

-diptheria
- pertussis (whooping cough)
- tetanus