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

Question 1

describe helicobacter pylori

Answer 1

• gram negative vibrio

Question 2

what chemical reaction does helicobacter pylori cause

Answer 2

urea + H2O -> CO2 + ammonia

Question 3

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

Answer 3

-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

Question 4

how do organisms survive the acidity of stomach juices

Answer 4

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

Question 5

how are gastric ulcers treated

Answer 5

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

Question 6

what is the initial infection immune response of gastric ulcers

Answer 6

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

Question 7

what are the symptoms of helicobacter pylori

Answer 7

no symptoms in most people

Question 8

describe pseudomonas aeruginosa

Answer 8

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

Question 9

how are pseudomonas aeruginosa cells arranged

Answer 9

pairs

Question 10

what are the virulence factors for pseudomonas aeruginosa

Answer 10

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

Question 11

what is alginate’s possible contribution to virulence

Answer 11

biofilm formation

Question 12

describe opportunistic pathogens

Answer 12

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

Question 13

what types of pathogens are major problems in hospitals

Answer 13

opportunistic pathogens in nosocomial infections

Question 14

where are opportunistic pathogens seen in hospitals

Answer 14

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

Question 15

what characterizes pseudomonas aeruginosa

Answer 15

soluble blue green dye pyocyanin and pyoverdin

Question 16

describe the clinical features and epidemiology for pseudomonas aeruginosa

Answer 16

• pulmonary (CF patients)
• nosocomial infection

Question 17

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

Answer 17

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

Question 18

describe bordetella pertussis

Answer 18

gram negative
- strict aerobe
- non motile, capsule

Question 19

what illness is caused by bordetella pertussis

Answer 19

whooping cough

Question 20

what does Bordetella pertussis show

Answer 20

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

Question 21

what is the virulence factors in whooping cough

Answer 21

• adhesion to ciliated respiratory tract cells but NOT invasive
• toxins

Question 22

what toxins are virulence factors for pertussis

Answer 22

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

Question 23

what does pertussis toxin ptx do

Answer 23

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

Question 24

what does secreted invasive adenylate cyclase/hemolysin do

Answer 24

increase cAMP

Question 25

what does tracheal cytotoxin do

Answer 25

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

Question 26

what is the bordetella pertussis treatment and epidemiology

Answer 26

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

Question 27

describe corynebacterium diptheriae

Answer 27

• gram positive pleiomorphic rods
• opportunistic pathogen
• oral pathogen with systemic effects

Question 28

what are the characteristics of diptheria and mechanism of action

Answer 28

• 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

Question 29

what chemical reaction is caused by diptheria

Answer 29

NAD + EF2 -> ADP ribose EF2 + nicotinamide

Question 30

what are the virulence factors for diptheria

Answer 30

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

Question 31

what are local and systemic disease risks from diptheria toxin

Answer 31

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

Question 32

what is the treatment and epidemiology for diptheria toxin

Answer 32

• prevent by toxoid vaccination
• spread by saliva droplets

Question 33

what illnesses does the DPT vaccine protect against

Answer 33

-diptheria
- pertussis (whooping cough)
- tetanus