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obligate aerobes
Absolute requirement for O2 to grow
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Obligate anaerobes
- Grow only under conditions of high reducing intensity (anaerobic system w/ 0% O2)
- O2 is toxic
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¢Facultative anaerobes
Grow under aerobic or anaerobic conditions
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Microaerophiles
- Grow best under lower O2 intensity (anaerobic system w/ 0% O2 or in 10% CO2, 85% N2, 5% O2
- Higher O2 tensions may be inhibitory (no growth in CO2 incubator with 5% CO2, 15% O2 or in ambient air with about 21% O2
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¢Aerotolerant anaerobes
- Anaerobes that are not killed by exposure to O2
- Best growth in anaerobic system w/ 0% O2
- Moderate growth in 10% CO2, 85% N2, 5% o2
- Less growth in CO2 incubator, 5% CO2, 15% O2
- Less growth in ambient air about 21% O2
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Name a species that is anaerobic, Gram pos, bacilli, and a spore former. Name 6 organisms in this group.
- ¢Clostridium spp
- 1.C. perfringens
- 2.C. difficile
- 3. C. botulinum
- 4.C. histolyticum
- 5.C. septicum
- 6.C. tetani
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List 6 species that are anaerobic, Gram pos, bacilli, and non-spore formers.
- 1.Actinomyces spp
- 2.Bifidobacterium spp
- 3.Eubacterium spp
- 4.Lactobacillus spp
- 5.Mobiluncus spp
- 6.Propionibacterium spp
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Name a species the is anaerobic, gram pos cocci, and a non-spore former. Name 2 organisms in this species.
- ¢Peptostreptococcus spp
- 1.P. anaerobius
- 2.P. asaccharolyticus
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Name 1 organism and 1 species that are anaerobic and gram pos cocci.
- Staphylococcus saccharolyticus
- Streptococcus spp
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Name 6 species that are anaerobic Gram neg bacilli.
- 1.Bacteroides
- 2.Bilophila
- 3.Campylobacter
- 4.Fusobacterium
- 5.Porphyromonas
- 6.Prevotella
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Name 3 anaerobic Fusobacterium species.
- ¢F. mortiferum
- ¢F. necrophorum
- ¢F. nucleatum
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Name an important anaerobic Porphyromonas organism.
¢P. asaccharolytica
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Name 2 important anaerobic Prevotella organisms.
- ¢P. intermedia
- ¢P. melaninogenica
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Name 2 species of anaerobic gram neg cocci.
- Veillonella
- Megasphaera spp.
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Strict anaerobes die within _____ minutes of _______ exposure.
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Name 3 enzymes that moderate anaerobes can use to protect themselves from the toxic effects of O2 production. Can anaerobes that do not produce these enzymes still have a high level of virulence?
- catalase
- superoxide dismutase
- peroxidase
- yes
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What do catalase and peroxidase break down?
¢H2O2 to H2O and molecular O2
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Catalase is found in what type of bacteria?
Peroxidase is found in several ________ anaerobes.
- aerobic or facultative bacteria
- Peroxidase found in several aerotolerant anaerobes
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What enzyme converts superoxide radicals to H2O2 and molecular O2?
Superoxide dismutase
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Describe Phase 1 of the sensitivity of anaerobes to O2.
- When anaerobes are placed into an O2-containing atmosphere, electrons normally available for cellular metabolic processes are diverted to the reduction of molecular O2.
- Metabolic processes stop which leads to a complete cessation of growth.
- This is a bacteriostatic effect, which is reversible up until the time of Phase 2.
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