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Cl Perf+ Cl Botu
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Cl Perf+ Cl Botu

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    Cl Perf+ Cl Botu Cl Perf+ Cl Botu Presentation Transcript

    • Clostridium perfringens Clostridium botulinum Dr Kamran Afzal Classified Microbiologist
    • Clinically important Gram positive bacilli
      • Spore forming
      • 1. Bacillus
      • 2. Clostridium
      • Non spore forming
      • 1. Corynebacterium
      • 2. Listeria
      • Bacilli w/ branching filaments
      • 1. Actinomyces
      • 2. Nocardia
    • Spores
    • Spores
      • Clostridia form endospores under adverse environmental conditions
      • Spores are a survival mechanism
      • Spores are characterized on the basis of position, size and shape
      • Most Clostridium spp., including Cl. perfringens and Cl. botulinum , have ovoid subterminal (OST) spores
      • Cl. tetani have round terminal (RT) spores
    • Classification Based On The Type Of Disease Produced
      • A . Tetanus Cl. tetani - Present in soil
      • B. Gas gangrene
        • Established Cl. perfringens ‘gut’ organism
        • Cl. septicum
        • Cl. novyi
        • - Less pathogenic Cl. histolyticum
        • Cl. fallax
        • - Doubtful Cl. bifermentans
        • Cl. sporogenes
      • C. Food poisoning
      • 1. Gastroenteritis Cl perfringens Type A
      • 2. Botulism Cl botulinum Soil
      • 3. Pig-bel Cl perfringens Type C
      • D. Acute colitis - Cl difficile Gut
      • (pseudomembranous colitis)
        • Commonest cause of ‘nosocomial’ diarrhoea
    • Introductory Characteristics
      • Obligate anaerobes
      • Gram positive
      • Capable of producing endospores
      • Rod-shaped
        • Greek word for spindle, kloster
      • Club-shaped
        • Endospores form club end
    • Clostridium Associated Human Diseases
    • Clostridium perfringens
    • Characteristics
      • Gram positive
      • Rod-shaped
      • Non-motile
      • Anaerobic
      • Capsulated
      • Double zone of haemolysis
      • Five types of strains
          • A - E
      • Four lethal toxins
          • Alpha, Beta, Epsilon and Iota
    • Epidemiology
      • Lives in soils esp manured and cultivated lands
      • Persists in human and animal intestinal tracts and faecal matter
      • Can survive higher temp (45 0 C)
      • Doubling time can be as short as 8 minutes
      • Food poisoning strains produce spores that can resist boiling for several hours
      • Gas gangrene strains produce spores that are inactivated by boiling for few minutes
    • Virulence Factors Major Minor
      • Enzymes
        • Hyaluronidase, Proteinase and Collagenase
    • Lab Diagnosis
      • Large rectangular gram-positive bacilli
      Inner beta-hemolysis = θ toxin Outer alpha-hemolysis = α toxin
      • Double zone of haemolysis
      • Lack of inflammatory cells
      • Nagler Reaction (egg-yolk agar)
      NOTE: Lecithinase ( α -toxin; phospholipase) hydrolyzes phospholipids in egg-yolk agar around streak on right. Antibody against α -toxin inhibits activity around left streak Cl perfringens Cl histolyticum Cl septicum Cl novyii
    • Clostridial food poisoning
      • Cl perfringens
      • Heat resistant Enterotoxin
      • Carriers for food poisoning strains
      • Survival of heat resistant spores in bulk meals
      • Sporulation in gut - Short IP and watery diarrhoea for 24-48 hours
      • Usually symptoms occur within 6-24 hours of ingestion and can last ~24 hours
      • Salmonella spp
      • Staphylococcus aureus
      • Campylobacter spp
      • Clostridium perfringens
    • Necrotizing enteritis (Pig-bel)
      • New Guinea natives have pork feasts
      • Clostridia survive in under-cooked meat
      • Production of Beta toxin by Cl perfringens Type C
      • Beta toxin acts on small intestine
    • Gas Gangrene
    • Pathogenesis
          • Dead tissue, blood clots, aerobic organisms
              • In an injury
      • Development of ANAEROBIC CONDITION
      • (Exogenous infection) Germination of spores
      • Gas gangrene
      • oedema, necrosis, gas production
      • toxaemia, myositis
      • crepitus
    • Management
      • Prompt surgical intervention
        • Sutures are removed, fascial compartments are incised to release tension, necrotic tissue is debrided
      • Hyperbaric oxygen
        • Special pressurized chamber
      • Antitoxin antiserum
        • A polyvalent antitoxin antiserum containing Cl perfringens , Cl novyii and Cl septicum antitoxin
        • Now replaced with intensive antimicrobial therapy
      • Antimicrobial therapy
    • Clostridium botulinum
    • Epidemiology
      • Found in soil, sediments of lakes, ponds, coastal waters, decaying vegetation
      • Intestinal tracts of birds, mammals and fish
      • Usually seen in canned foods
        • Hams, sausages, fish, liver paste, honey and home preserved meat products and vegetables
    • Characteristics
      • Anaerobic Gram-positive bacillus that forms oval sub-terminal spores
      • Botulinum Toxin - One of the most poisonous natural substances known
      • Seven toxigenic subtypes of the organism
        • A, B, C, D, E, F and G
        • The principle cause of human disease A,B and E
    • Spores
      • Spores can withstand boiling in water for several hours
      • Destroyed by moist heat at 120 0 C within 5 min
      • Insufficient heating in the process of preserving foods – Botulism
      • Canning factories should ensure ‘adequate heating’ in all parts of canned contents
      • Resistance of some spores to irradiation
    • Action of Toxin
      • Structure: Synthesized as a polypeptide chain that cleaves into two chains, a light and heavy linked by disulfide bonds
      • Blocks release of Ach
        • Failure to release neurotransmitter
        • Zinc-dependent endopeptidase that
        • cleaves synaptobrevins
      • Flaccid Paralysis
      • Permanent binding and damage
    • Mechanism of Action of Toxin
      • Toxin is neurotoxic protein
      • Not inactivated by stomach / intestinal enzymes
      • Destroyed by heating at 100 0 C for 20 mins
      • Action : Block release of Acetylecholine at synapses and NMJ of peripheral and cranial nerves - flaccid paralysis
    • Symptoms
      • Begin 8-36 hours after ingestion
      • Length : 2 hours to 14 days after entering circulation
      • Preliminary symptoms: weakness, dizziness, dryness of mouth, nausea, vomiting
      • After Neurological disturbance: blurred vision, inability to swallow, difficulty in speech, descending weakness of skeletal muscles
      • Respiratory paralysis and cardiac failure - death
    • Clinical Syndromes
      • Flaccid paralysis
      • Food-borne: ingestion of foods in which spores have germinated and grown in, considered an intoxication – most common form
      • Wound: infects a wound and then produces toxins that spread through the bloodstream – very rare
      • Infant: infection establishes itself in the bowels of infants, colonizes and produces the toxin – common source is honey
      • Unidentified: source is unknown, usually from intestinal colonization with in vivo production of toxin – usually from surgeries
    • Lab diagnosis
      • Clinical samples
        • Suspected food, faeces or vomitus
        • Cl botulinum cultured anaerobically
      • Toxin detection
        • Toxin-Anti toxin neutralization by inoculation in mice
    • Treatment
      • Priorities
        • To remove unabsorbed toxin from stomach and small intestine
        • To neutralize unfixed toxin by giving polyvalent antitoxin (A,B and E)
        • To give relevant intensive care and support
      • Penicillin or other beta-lactam antibiotics?
      • A prophylactic dose of polyvalent antitoxin should be given to all the persons who have eaten ‘suspicious food’ containing botulism toxin
    • Alternative botulism uses
      • Botox
        • A-Type botulism is an
        • active ingredient
      • Biological Warfare
        • Poisonous to humans
        • World War II
          • gelatin capsules with a lethal dose
          • slipped into food or drink
          • 1 gram crystalline toxin dispersed evenly and inhaled = 1 million deaths
      • What are the causative agent(s) of gas gangrene?
        • Cl. perfringens
        • Cl. novyii
        • Cl. difficile
        • Cl. septicum
        • Cl. botulinum
      • What are the causative agent(s) of gas gangrene?
        • Cl. perfringens
        • Cl. novyii
        • Cl. difficile
        • Cl. septicum
        • Cl. botulinum
      • Which one is not a Clostridial toxin?
        • Neurotoxin
        • Histotoxin
        • Aflatoxin
        • Enterotoxin
      • Which one is not a Clostridial toxin?
        • Neurotoxin
        • Histotoxin
        • Aflatoxin
        • Enterotoxin
    •  
    •