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C. McKenzie F2013 Modified by DYH Bacterium: Clostridium botulinum • Division: Firmicutes • endospore-forming • obligate anaerobic (can tolerate moderate oxygen levels due to anti-oxidant enzyme superoxide dismutase) • Mesophilic (optimal temperature approx. 37C) • Rod-Shaped (exists individually, in pairs, or a linked chain) • Gram-positive bacteria. • Genome Size: 4,039 kbp • • Larger than most Gram-positive bacteria due to presence of endospore (temperate phage) and botulin toxin (hemagglutinin A) Presence of transposon Tn916 sites • 7 confirmed strains (A-G) composed in to 5 groups based on toxin subtype. • Recent discovery of what is believed to be a new, 8th, strain – Type H • Sequence withheld from public because international threat due to lack of antidote. http://microbewiki.kenyon.edu/images/thumb/7/77/B2201272Clostridium_botulinum_bacteria-SPL.jpg/400px-B2201272Clostridium_botulinum_bacteria-SPL.jpg C. botulinum Pathogenesis • Botulin exotoxin results in botulism • Types A, B & E are pathogenic in human (Groups 1 and 2 particularly) • Toxin is one of most powerful known: • One-millionth of a gram enough to kill average human • Methods of transmission: 3 • Aerosol (terrorism/chemical warfare); wound infection; and food borne ingestion (botulism and infant botulism) • Method of action: • Botulin toxin enters circulatory system and arrives at peripheral nerve synapses • At PNS synapse it blocks the release of neurotransmitter acetylcholine (ACh). • Without neural signaling skeletal muscles fail to contract and thus paralysis is induced. • Sold commercially for medical cosmetic procedures: • Toxin type A (Botox®, Dysport® and Xeomin®) and toxin type B (MyoBloc®) http://www.studentpulse.com/articleimages/uploaded/324_1.jpg C. McKenzie F2013 Modified by DYH