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 G_i 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 G_s 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