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Micro - anaerobes


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What do Clostridium spp. look like? What are some common characteristics?
*G+ "boxcar" rod
*O2 tolerance varies
*found in soil
What 2 disease forms are associated with C. perfringens?
*post-traumatic gas gangrene
*food poisoning
What organism causes non-traumatic gas gangrene?
C. septicum
What are some virulence factors for C. perfringens?
*variety of proteolytic and histotoxic enzymes
*gas production
*Phospholipase C
What are some diagnostic characteristics of C. perfringens?
*distinctive gram appearance
*double zone of hemolysis on SBA
How is an infection with C. perfringens usually treated?
*surgical debridement or amputation
What are the 3 disease forms of C. botulinum?
1.Infant botulism
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?
*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?
*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?
*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?
*muscle spasm
*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?
*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?
*metronidazole, or vancomycin, or probiotics
*relapse occurs in 20% of pts.
Where is propionibacterium normally found? What kind of disease is it associated with?
*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?
*G+ branching rod (sometimes confused with Nocardia)
*normal flora of oropharynx
*agent for Lumpy Jaw
What are two virulence factors for Bacteroides fragilis?
*antiphagocytic capsule
What type of infection does Bacteroides typically cause?

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