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37 Cards in this Set

  • Front
  • Back
What are 3 characteristics of anaerobic bacteria that make them sensitive to oxygen
1. have little superoxide dismutase
2. have low amounts of catalase
3. lack cytochromes
Bacteroides - fragilis group
intra-abdominal infections
Bacteroides - pigmented group
oral, dental, pleuropulmonary infections
Bacteroides - bivius
pelvic infections
Infections by gram - pathogens are often...
foul smelling
what is a interesting product of fermentation by gram - pathogens?
microbial nature of anaerobic infections are often due to what?
contamination of tissues by normal flora
What is the important gram negative anaerobic bacteria that we talked about?
bacteriodes fragilis
Where does bacteriodes fragilis live in healthy people?
the bowel
What is special about the LPS of bacteriodes fragilis?
it is modified and does not stimulate TLR and therefore there is no inflammation
What is the way to grow b. fragilis on an agar?
use sbile-esculin agar with gentamicin and the black stuff is what you want
Histologically what does bacteroides fragilis look like?
faintly staining, pleomorphic, gram negative bacilli
What are the 4 mechanisms of virulence force in anaerobic bacteria?
1. adhesion (capsule, fimbrea)
2. Resistance to O2 toxicity
3. Antiphagocytic (capsule, Ig, lipopolysaccharide)
4. Tissue distruction
What are the major characteristics of clostridia?
anaerobic gram positive, spore forming bacilli
What is the pathogenesis of clostridia due to?
an exotoxin
what do clostridia eat?
sugars or aa
Where do clostridia live?
soil or intestines
What is the clostridia that causes gastroinestinal disease?
c. difficile
What causes histotoxic clostridia?
c. perfringens
What causes tetanus?
c. tetani - non-invasive, toxin producing
What causes botulism?
c. botulinum
food poisoning - intoxication
What causes the majority of clostridia-mediated myonecrosis?
c. perfringens
What are some characteristics of c. perfringens?
non-pahtogenic in healthy tissue
What are the 2 steps in a c. perfringens infection?
1. reduction of tissue redox potential (host cell death)
2. endogenous protease (relases nutrients)
What predisposes someone to a c. prefringens infection?
deep muscle wound

gas gangrene occurs
What is the structure of botulism and tetanus toxins?
How do neurotoxins of clostridia work?
they clip SNARES so that vesicles cannot bind presynaptically so NT is not released
What is tetanus like?
spastic paralysis in the area of infection (non-invasive)
How is tetanus toxin activated?
single polypeptide cleaved via a S-S reduction using a zinc protease
How do you Tx suspected cases of tetanus?
administer anti-TT

not effective after toxin enters the cells
What are the main characteristics of botulism?
A:B toxin activated by a zinc protease
heat labile
7 serotypes (A-G) A,B,E are in humans
What are the 3 ways to get botulism?
1. food borne
2. Infant - spore-mediated
3. Wound - war setting
What type of paralysis do you get with botulism?
What food poisoning bacteria did we learn about that is heat stable?
How does tetani travel?
retroaxonlally to in interneuron where it inhibits relase of NT
How does botulism travel?
inhibits release of Ach at presynaptic memb of presynaptic neurons
Where is botox used clinically?