Can facultative anaerobes use pathways other than those requiring oxygen as a terminal electron receptor to generate ATP?
Yes
. When oxygen is unavailable, facultative anaerobes generate _____ primarily through _____ or _____ _____.
When oxygen is unavailable, facultative anaerobes generate ATP primarily through fermentation or anaerobic respiration.
Which class of antibiotics is not effective against anaerobes?
_____
Aminoglycosides
Aminoglycosides require _____ to enter a _____ cell.
oxygen
bacterial
Although anaerobes are pathogenic
in most tissues, where are they most commonly part of the microflora?
_____ _____
Gastrointestinal tract
Why do anaerobes have increased susceptibility to oxidative damage?
They lack the enzymes _____ _____ and/or _____
They lack the enzymes superoxide dismutase and/or catalase
What properties with regard to oxygen use do Clostridium,
Bacteroides, Fusobacterium, and Actinomyces
israelii share?
They are all [aerobes/anaerobes]
They cannot survive in
oxygen-[rich/poor] environments
They are all anaerobes
They cannot survive in oxygen-rich environments
Which class of bacteria, known for having a foul
smell and being difficult to culture, produces
CO2 and H2 gas in tissues?
[Aerobes/Anaerobes]
Anaerobes
Low activity of which neurotransmitters results in the
spastic paralysis, risus
sardonicus, trismus, and
opisthotonos caused by tetanospasmin?
____
____
Glycine
GABA
How does the heat-stable toxin of
enterotoxigenic Escherichia coli cause
watery diarrhea?
By decreasing the ability of the gut to reabsorb _____ and _____
secondary to overactivation of guanylate cyclase
NaCl
H2O
What is the mechanism of the heat-labile toxin of enterotoxigenic
Escherichia coli?
_____ _____ is activated causing greater secretion of
Cl- and H2O in the gut
Adenylate cyclase
Heat-stable toxin from ETEC overactivates _____ _____ → increases _____ → decreases intestinal absorption of NaCl.
guanylate cyclase
cGMP
Identify the exotoxin responsible for persistent cough for 3 months
in a teacher who teaches students not currently fully vaccinated.
____ toxin
Pertussis toxin
Which bacteria have exotoxin A, which inactivates EF-2 to trigger host cell death?
_____ _____
Pseudomonas aeruginosa
Name the functions of the A and B components of ADP ribosylating AB
toxins found in Corynebacterium diphtheriae.
The A component is _____
The B component binds and triggers _____
The A component is active
The B component binds and triggers endocytosis
B = Binding component
It binds
the host cell receptor and brings the toxin into the cell.
A = Active component
It enters
the cytoplasm and ADP-ribosylates EF-2, shutting down
protein synthesis.
In a patient with scarlet fever caused by Streptococcus pyogenes, what specific toxin is to blame for the symptoms?
_____ _____ _____
This causes ____ ____ -like syndrome.
Erythrogenic exotoxin A
toxic shock
Name three toxins produced by Staphylcoccus aureus and their
associated symptoms.
_____ _____ _____ toxin → Rash, fever, and shock
_____
toxin → Scalded-skin syndrome
_____ → Diarrhea and vomiting
Toxic shock syndrome toxin → Rash, fever, and shock
Exfoliative
toxin → Scalded-skin syndrome
Enterotoxin → Diarrhea and vomiting
What is the mechanism of anthrax toxin, released by Bacillus anthracis?
Mimics _____ _____ → Edematous borders of [color] _____
Mimics adenylate cyclase → Edematous borders of black eschar
What is the mechanism by which the Shiga toxin
causes damage to the gastrointestinal mucosa and dysentery?
Removes ____ from rRNA → Inactivation of the ____ ribosomal subunit
Removes adenine from rRNA → Inactivation of the 60S ribosomal subunit
What is the mechanism by which streptolysin O toxin leads to hemolysis?
Streptolysin O degrades red blood cell _____ → _____ -hemolysis
Streptolysin O degrades red blood cell membranes → β-hemolysis
What is the mechanism of botulinum toxin?
Botulinum toxin inhibits release of acetylcholine at the _______
junction by cleaving _______ proteins
Botulinum toxin inhibits release of acetylcholine at the neuromuscular junction by cleaving SNARE proteins
What is the mechanism of action of the alpha toxin of Clostridium perfringens?
Alpha toxin is a phospholipase that degrades _____ → _____ and _____
Alpha toxin is a phospholipase that degrades phospholipids → Myonecrosis and hemolysis
Why does Clostridium perfringens lead to hemolysis
when cultured in a blood agar?
This is due to the _____ toxin→ Forms a _____ zone of hemolysis
on blood agar
This is due to the alpha toxin→ Forms a double zone of hemolysis on blood agar
On blood agar, Clostridium perfringens classically causes a double zone of hemolysis:
Inner zone = _____ hemolysis
Outer
zone = _____ hemolysis
Inner zone = complete hemolysis
Outer
zone = partial hemolysis
What is the mechanism of the offending toxin of Bordetella pertussis?
The pertussis toxin disables the _____ protein
This overactivates _____ _____.
The pertussis toxin disables the Gi protein.
This overactivates adenylate cyclase.
Name two common gram-positive bacteria that can
cause a rash and septic shock.
_____ _____
_____ _____
Staphylococcus aureus
Streptococcus pyogenes
How does the AB toxin in Vibrio cholerae cause water diarrhea?
AB toxin permanently activates _____ protein → Stimulates _____
_____ → Increases Cl- and H2O secreted in the gut
AB toxin permanently activates Gs protein → Stimulates adenylate cyclase → Increases Cl- and H2O secreted in the gut
What is the mechanism by which superantigens cause toxic shock syndrome?
Superantigens binds to MHC ____ molecules and ____ receptors →
Overwhelming release of ____
Superantigens binds to MHC II molecules and T-cell receptors → Overwhelming release of cytokines
What is the mechanism of the diphtheria toxin?
Inactivates ______ via ______ ______→ Pseudomembranous
pharyngitis, bull neck, and myocarditis
Inactivates EF-2 via ADP ribosylation → Pseudomembranous pharyngitis, bull neck, and myocarditis
A 35-year-old male presents to the clinic with the complaints of sore throat and trouble swallowing. The patient is an Iranian immigrant who states that his throat discomfort has been getting worse over the past 4 days. The patient says he has not been eating because of the pain. Physical examination reveals mild fever and a dark gray coating in the back of the mouth. Palpation of the neck reveals enlarged cervical lymph nodes and signs of edema. The organism causing this disease has which mechanism of action?
A. blocks neuronal transmission
B. blocks protein synthesis
C. blocks release of acetylcholine
D. causes increase of cAMP
B. blocks protein synthesis
Exotoxin A from Pseudomonas aeruginosa and diphtheria toxin from Corynebacterium diphtheriae both inhibit ______
EF-2