Lecture 9 - Clostridium Flashcards
what are the 4 species of clostridium prevalent in human disease?
also name the diseases they cause
clostridium perfringens – gas gangrene
clostridium tetani – tetanus
clostridium botulinum – botulism
clostridium difficile – diarrhea, colitis
which of the 4 clostridium species dicussed form spores?
ALL OF THEM DO
which of the 4 clostridiums discussed are prevalent in hospital environments and are the cause of some nosocomial infections?
clostridium difficile
name the 4 general properties of the clostridium family
-can form endospores (thus can survive in harsh environmental conditions)
-ANAEROBIC METABOLISM (strict)
-Inability to reduce sulfate to sulfite
-gram POSITIVE cell wall
in general, where is the clostridium family present
ubiquitous (everywhere) in soil, water, sewage, AND endogenous flora
how does the clostridium family induce damage (as a general rule)
through toxins (specific for each species)
true or false
clostridium bacteria are not part of our endogenous flora
FALSE – they are
what is the toxin for clostridium tetani
tetanospasmin
what is the toxin for clostridium perfinges
alpha toxin, Iota toxin, and enterotoxin
what is the toxin for clostridium botulinum
botulinum
what is the toxin for clostridum difficile
A enterotoxin and B cytotoxin
which clostridium species causes antibiotic-associated diarrhea?
clostridium difficile
which clostridium species causes gangrene?
clostridium perfringens
how many types of clostridium perfringes are there? what does the type depend on which type is the mot prevalent in humans?
5 different types, depending on their toxin production
A-E
A is the most prevalent in humans
name the lethal toxins of clostridium perfringes.
state their function and which is the “worst” for the host cell
alpha toxin – same function as phospholipase C (break down cell membrane) and also causes hemolysis
Iota toxin – is an A-B toxin. B subunit forms pores and A subunit binds G actin
enterotoxin – hate labile toxin. causes fluid loss and also acts as a superantigen
what kind of infections does clostridium perfringes cause?
soft-tissue infections from cellulitis to gangrene
explain what gangrene is
occurs when bacteria that are rapidly dividing produce a gas metabolite that leads to edema and necrosis (death of cells of tissue)
besides soft tissue infections, what other conditions can clostridium perfringens cause
food poisoning, endometritis, sepsis, necrotizing enterocolitis
what is unique about clostridium tetani
the bacteria itself has extreme oxygen sensitivity – will die in the presence of oxygen, but the spores can persist in an oxygen rich environment (such as in open wounds)
name the toxins of clostridium tetani
tetanospasmin (A-B toxin)
tetanolysin
explain what tetanospasmin does
is released when the cell lyses.
invades spinal motor neurons of the CNS and undergoes retrograde transport to the soma (body) of the cell.
it BLOCKS INHIBITORY NEUROTRANSMITTER RELEASE (GABA) and causes continuous excitatory neurotransmission
what does tetanolysin do
pore-forming toxin
what is the main symptom of a clostridium tetani infection
tetanus
what muscles are often the first affected in tetanus?
masseter muscles (lock jaw)
more and more muscles are involved with time — affects swallowing and respiration
where is clostridium botulinum common?
in soil and in water
in what conditions do the spores of clostridium botulinim germinate?
in anaerobic conditions
which spores of the clostridium family are heat resistant?
botulinum
there are ______ distinct subunits of the Botulinum toxin.
name and explain 2 of them
what does the botulinum toxin as a whole cause?
7 subunits of the botulinum toxin
A subunit — is zinc endopeptidase. inhibits the release of acetylcholine (OPPOSITE OF TETANUS TOXIN)
B subunit – binds sialic acids and glycoproteins on motor neurons
causes paralysis!!!
name 4 ways in which you can get botulism
foodborne (canned foods)
powdered milk (infants)
through a wound (rare)
inhalation – biological weapon??
why is the botulinum toxin so popular in the cosmetic industry?
it loosens and relaxes the muscles – they CANNOT be stimulated. leads to no wrinkles
botulinum toxins blocks ______ release at the _____
blocks acetylcholine release at the neuromuscular junction
where does clostridium difficile colonize? how is its virulence kept in check?
the large intestine
virulence kept in check by NORMAL FLORA and DIMERIC IGA
explain how a clostridium difficile infection develops
toxin-producing clostridium difficile proliferates following broad-spectrum antibiotic treatment (no more flora to keep it in check)
the SPORES of clostridium difficile are common where?
in hospital settings – major source of nosocomial outbreaks.
relapse occurs due to presence of spores
what are the symptoms of a clostridium difficile infection
can be benign, but also can cause severe diarrheal disease (pseudomembranous colitis)
name the toxins of clostridium difficile
enterotoxin (toxin A)
Cytotoxin (toxin B)
explain what enterotoxin (toxin A) of clostridium difficile does
it is a chemoattractant for neutrophils, which in turn stimulates cytokine release, which in turn disrupts tight junctions. – makes it easier to get in
explain what cytotoxin (Toxin B) of clostridium difficile does
induces actin depolymerization — gives bacteria ability to move cell to cell
virulence of clostridium difficile is increased with increased……..
what is this caused by?
INCREASED TOXIN PRODUCTION
caused by a mutated regulatory gene
