Micro - anaerobes
Terms
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- What do Clostridium spp. look like? What are some common characteristics?
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*G+ "boxcar" rod
*O2 tolerance varies
*spore-forming
*found in soil - What 2 disease forms are associated with C. perfringens?
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*post-traumatic gas gangrene
*food poisoning - What organism causes non-traumatic gas gangrene?
- C. septicum
- What are some virulence factors for C. perfringens?
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*variety of proteolytic and histotoxic enzymes
*gas production
*Phospholipase C - What are some diagnostic characteristics of C. perfringens?
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*distinctive gram appearance
*double zone of hemolysis on SBA - How is an infection with C. perfringens usually treated?
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*surgical debridement or amputation
*PCN-G - What are the 3 disease forms of C. botulinum?
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1.Infant botulism
2.Food-borne
3.Wound - How do kids get infant botulism?
- It occurs at weaning, when the change in diet causes a change in GI flora. Obtained from the environment esp. honey.
- How do people get food-borne botulism?
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*ingestion of pre-formed toxin
*From improperly canned foods - What population is most likely to contract wound botulism?
- SC drug abusers.
- Describe the pathogenesis of C. botulinum.
- Synth a heat and acid-stable A+B toxin that binds the presynaptic membrane and inhibits release of ACh.
- What symptoms are seen with infection by C. botulinum?
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*descending flaccid paralysis
*slurred speech in adults, poor suck in peds
*difficulty swallowing and breathing - How is infection with C. botulinum diagnosed?
- Detection of the toxin
- When is C. tetani usually acquired?
- Due to trauma.
- What happens following invasion of C. tetani?
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*synthesis of tetanospasmin toxin
*toxin binds at NMJ and travels up the axon to disseminate through nervoous system
*blocks release of GABA - What symptoms are seen in infection with C. tetani?
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*muscle spasm
*seizure
*trismus
*difficulty breathing - How is an infection with C. tetani usually diagnosed?
- Based upon clinical findings only.
- What usually precedes an active C. difficile infection?
- Antibiotic treatment.
- What are the symptoms of C. difficile infection?
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*diarrhea
*nonspecific or pseudomembranous colitis - How is pathogenesis mediated in infection with C. difficile?
- Synthesis of an exotoxin.
- How is infection with C. difficile treated? Is this usually successful?
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*metronidazole, or vancomycin, or probiotics
*relapse occurs in 20% of pts. - Where is propionibacterium normally found? What kind of disease is it associated with?
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*normal flora of skin, sebaceous glands, and hair follicles
*common cause of device-related meningitis - What does Actinomyces look like? Where is it normally found? What condition is it associated with?
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*G+ branching rod (sometimes confused with Nocardia)
*normal flora of oropharynx
*agent for Lumpy Jaw - What are two virulence factors for Bacteroides fragilis?
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*antiphagocytic capsule
*B-lactamase - What type of infection does Bacteroides typically cause?
- Abscess