Anerobes Flashcards
Where can anaerobes be found?
Mucosal surfaces
What is the benefit of a mixed infection of both aerobic and anaerobic bacteria?
Aerobic bacteria can break down oxygen and create a more favorable environment for anaerobes
What are anaerobes not great in oxygenated environments?
Have little enzymes (superoxide dismutase, catalase) to deal with O2 intermediates
Where do anaerobic gram negative pathogens colonize?
colon, mouth, skin
What are foul-smelling infections caused by?
Anerobic gram neg bacteria that make short chain fatty acids in fermentation
What is the virulence factor of Bacteriodes fragilis?
Polysaccharide capsule
What is the oxygen metabolism of Bacteriodes fragilis?
it’s an aerotolerant anaerobe with oxidative stress response genes
Where is Bacteriodes fragilis found?
Commonly in the bowel
What can bacteriodes uniquely grow on? What color is it on the plate?
Bile-esculin agar (bile and gentamicin, and able to break down esculin).
Black
Describe the stain and shape of Bacteroides fragilis
Gram negative bacilli
What is characteristic of Bacteroides fragilis?
Long chains on gram stain–filamentous structure of gram negative bacilli
Clostridia gram stain, shape, and metabolism
anaerobic, bacilli, gram positive, also make spores
How are Clostridia pathogenic?
Exotoxin
Where are Clostridia found?
In soil or intestinal tract
How are Clostridium difficile pathogenic?
Toxins A and B
How are Clostridium perfringens pathogenic?
invasive
How is Clostridium tetani pathogenic?
toxin
HOw is Clostridium botulinum pathogenic?
intoxication-food poisoning, botulism
What is notable about antibiotic treatments’ relationship with C. difficile?
antibiotics reduce amount of normal flora and allow endogenous or consumed C. difficile to multiply and make toxins A and B–>diarrhea and inflammation
How do Toxin A and B cause disease with C. difficile?
Glucosylate Rho GTPases-causes actin depolymerization-messes up gut epithelialcells–diarrhea
What is C perfringens known for?
Gas producing gangrene (necrosis)
What is the mechanism of pathogenesis of Clostridium perfringens?
Causes lactate production, lowered pH, damages host cells, damaged host cells release nutrients that help Clostridia grow, makes alpha toxin (producing gas gangrene)
What is Clostridium botulism known for?
Flaccid paralysis
What is Clostridium tetani known for?
Spastic paralysis
What kind of toxins are the botulinum and tetanus toxins?
Neurotoxins with AB structure
How do Clostridium neurotoxins work?
Proteases for SNARE
What is the shared mechanism of botulinum and tetanus toxins?
Proteases for SNARE
Where does botulinum toxin work?
presynaptic terminal of peripheral neurons–inhibiting Ach release and causing flaccid paralysis
Where does tetanus toxin work?
CNS-inhibits interneuron fxn, causing spastic paralysis
Pathogenicity of Clostridium tetani
not invasive-makes tetanus toxin
Pathogenicity of Clostridium botulinum
Botulinum toxin-AB toxin
How many kinds of botulinum toxin are there?
7 serotypes a, b, c, d, e, f, g
What are the types of Clostridium botulinum botulism cases?
C. botulinum in food (just the toxin)
Infection in infant botulism-spores consumed
Infection in wound botulism-spores in wound
Is botulism contagious?
No
Why are botulinum toxins useful in the clinic?
They target neurons specifically-and inhibit SNAREs
What do Bacillus and Clostridium have in common?
Make spores
HOw do you inactivate a spore?
120 C, 20 minutes
