5 - Gram Positive Bacilli Spore Forming Rods Bacillus and...

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Gram Positive Bacilli
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Spore Forming Rods Bacillus and Clostridium Release of potent exotoxins causes disease
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Bacillus anthracis Causative agent of anthrax UNIQUE protein capsule, antiphagocytic Aerobic growth conditions Spores are very stable, resistant to heat, drying, UV and disinfectants; spores germinate and toxins are made Humans exposed to spores usually through contact with animals or soil Used in bio-terrorism and warfare
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Bacillus anthracis exotoxin Encoded on pXO1 plasmid Plasmid contains virulence factors which are transcribed optimally @ 37 C, increased CO 2 and serum proteins ?? Where are these conditions found ?? Exotoxin composed of 3 separate proteins: Edema factor (EF) Protective antigen (PA) Lethal factor (LF) Separately proteins are not toxic, but combined are lethal pXO2 plasmid encodes capsule genes **BOTH plasmids required for virulence**
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Prevention and Treatment RAPID treatment is essential Antibiotics: penicillin, doxycyclin, ciprofloxacin or levofloxacin Vaccine against PA protein is available PENICILLIN
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Remember: capsule protects AND is made of protein cutaneous and respiratory routes for spores animal hides and/or soil
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Bacillus cereus Causes food poisoning when spores enter food product Motile, non-encapsulated, resistant to penicillin ENTEROTOXIN is responsible for illness 2 types of enterotoxin (i) Heat labile: nausea, abdominal pain, diarrhea. Lasts 12-24hrs (ii) Heat stable: SEVERE nausea and vomiting, short incubation Antibiotic treatment useless….preformed toxins
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Clostridium Anaerobic differentiates this bacteria from other spore-forming bacilli Botulism, tetanus, gas gangrene and pseudomembranous colitis POWERFUL EXOTOXINS RAPID DIAGNOSIS
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Clostridium botulinum Rapidly fatal food poisoning from lethal neurotoxin Neurotoxin blocks Ach release in autonomic system; flaccid muscle paralysis: Afebrile, bilateral cranial nerve palsies, double vision, trouble swallowing, muscle weakness Respiratory paralysis DEATH Treatment: antitoxin and respiratory assistance Smoked fish, improperly canned vegetables Proper cooking destroys spores
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Action of Botulinum Neurotoxin
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Infant Botulism Honey contamination with spores Spores germinate and bacteria colonizes intestine Neurotoxin release 2-3 days of constipation Trouble swallowing, muscle weakness
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Clinical Manifestations of Clostridium botulinum
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Clostridium tetani Tetanus Rusty nail contaminated with spores punctures skin; wound provides anaerobic environment Exotoxin: tetanospasmin Sustained contraction of skeletal muscles Severe muscle spasms (lock jaw); high mortality at this stage Booster (inactivated toxoid) given every 10 years
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Clinical Manifestations of Clostridium tetani
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Clostridium perfringens Gas gangrene Seen in soldiers wounded in battle 2 classes of infection: (i) Wound infection/cellulitis
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This note was uploaded on 03/02/2012 for the course ITI 1121 taught by Professor Samaan during the Winter '10 term at University of Ottawa.

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5 - Gram Positive Bacilli Spore Forming Rods Bacillus and...

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