Toxigenic Bacteria Flashcards
when are exotoxins produced?
During exponential growth phase (log phase)
What bacteria can produce exotoxins?
Both gram + and gram -
Define exotoxin
Exotoxin are diffusible proteins with enzymatic activities.
it blocks protein synthesis which causes cell death.
Where do exotoxins act?
Distally or locally at infection site and can function as invasins
what are the three basic types of exotoxins
A-B Type
Membrane disrupting
Superantigens
what is the function of a capsule?
protection against phagocytosis
what are the three forms of anthrax?
cutaneous (spread by insect bites or anthrax spores entering cut)
inhalation (anthrax spores in air)
gastrointestinal (infected meat)
what is the causative organism for Bacillus anthracis (anthrax)?
Large gram + aerobic rod with square ends
Encapsulated (cannot be phagocytosed)
It is an A2B Toxin
centrally located spores on nutritional depletion
what are Bacillus anthracis virulence factors?
poly-gamma-D-glutamate capsule -genes carried on pxO2
A2B Toxin - genes carried on pXO1
Spore formation
How to diagnose anthrax?
Gram stain for gram +
nasal swab only determines exposure
how to treat anthrax?
Antibiotics but mainly used for cutaneous
Monoclonal antibodies approved for inhalatioin anthrax
describe features of corynebacterium diphtheriae
gram + bacillus clubbed ends and palisading
aerobic
thick grey mucoid coat
colonizes throat and nasopharynx
describe diptheira toxin
low iron = high tox expression
ADP-ribosylates elongation factor 2 (EF-2)
Simple A-B toxin
binds to HB-EGF receptor
How do you treat bordetella pertussis?
antibiotics- blocks the spread
adequate oxygen support
what can cause dysbiosis?
an environmental trigger
how do you treat C.diff?
remove or change antibiotcs and fecal micrbiota tranplantation (FMT) works.
what are clostridial pathogens?
Clostridium tetani -blocks release of GABA and glycine
Clostrium botulinum -blocks acetylcholine release (no muscle contraction)
Clostridium perfringens -hydrolyses phospholipids which disrupts membrance
what is the difference between tetanus and botulinum toxin?
both affect vesicle traffic at synapse the difference is location of action.
tetanus prevents release of GABA and glycine which prevents muscle relaxation
botulinum blocks release of acetylcholine which stops muscle contraction
what is an endotoxin ?
a toxin released from bacterial cell when it disintegrates and comes from gram negative bacteria
virulence factors of bordetella pertussis?
1) Adhesins = attach to ciliated cells
2) adenlate cyclase (AC toxin) = increases cAMP
3) Pertussis toxin = inhibits G protein and increases cAMP
describe colonies of Psedomonas aeruginosa
fruity odor and blue-green pigment
minimal nutritional requirements
aerobic
virulence factors of Pseudomonas aeruginosa?
alginate = thick gel (antiphagocytic)
Exoenzyme S = ADP ribosylates G proteins
Exotoxin A = ADP ribosylates EF2
what 2 toxins do Clostridioides difficile produce?
TcdA
TcdB
what are the 3 major clostridium species?
Clostridium tetani
clostridium botulinum
clostridium perfringes - gas gangrene
virulence of clostridium perfringens?
alpha toxin: phospholipase C or lecithinase C
opportunistic infection of severe wound
gas from fermentation of tissue carbohydrates
CPE = claustridium perfringens enterotoxin: a pore forming enterotoxin; food poisoning
describe what an endotoxin is?
surrounds gram negative bacteria made of polymers of sugars and sugar phosphates attached to phospholipids
what is NAGNAM a component of?
peptidoglycan inner cell wall
what is maltose?
simple disacharride
what causes toxic shock syndrome?
exotoxins produced by bacteria specifically from superantigen (TSST-1)
what leads to membrane disruption?
phospholipid hydrolysis
