Gram Positive Rods

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Gram Positive Rods
2011-10-14 19:38:53
Case Study

Case Study
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  1. B. anthracis
    General Information
    • Heat kills vegetative cells but not spores
    • No hemolysis on blood agar
    • Zoonosis
  2. B. anthracis Virulence Factors
    • 1. Endospore
    • 2. Capsule (D-glutamic acid, not polysaccharide)
    • 3. Toxins
  3. Plasmids pX01 & pX02
    • pX01- all toxins are on this plasmid
    • pX02- capsule gene is on this plasmid
  4. Edema Toxin
    • Causes swelling of tissue (edema)
    • Protective antigen & Edema Factor
  5. Lethal toxin
    • Zinc metalloprotease causes macrophage to release cytokines -> massive inflammation
    • Protective antigen & Lethal factor
  6. Gastrointestinal Anthrax Infection
    Obtained from eating meat. Mainly an animal infection, but 100% mortality
  7. Innoculation Anthrax Infection
    Spores are absorbed on skin. Causes black marks ("eschar") on skin from necrosis. 20% mortality
  8. Inhalation Anthrax Infection
    • Inhale spores. They must be a specific size to get to the alveoli.
    • Pnemonia symptoms
    • Person to person transmission doesn't occur
    • Ciprofloxacin treats
  9. B. Cereus
    General Information
    • Opportunistic Pathogen
    • Ubiquitous, but mostly associated with rice and cereal
  10. Disease of B. Cereus
    • Food poisoning (oral fecal)
    • Catheter infection (bacteremia)
    • Occular disease if infects eyes
  11. Virulence Factors
    • Enterotoxins (heat stabile and heat labile)
    • Necrotic Toxin
    • Cereolysin
    • Spore
  12. Identification of B. cereus
    Culture contaminated food and feces
  13. Listeria monocytogenes
    General Information
    • Facultative anaerobe
    • A lot of flagella
    • Can multiply at refrigerator temperature
    • Weak beta hemolysis
  14. Disease of L. monocytogenes
    • Food borne infection (dairy, canteloupes)
    • Dangerous to newborns/fetus (can cross placenta)
    • Immunocompromised- meningitis
    • Healthy adults are usually subclinical
  15. L. monocytogenes Virulence Factors
    • Intracellular pathogen
    • Causes overproduction of actin in host cell which leads to endocytosis of bacteria.
  16. L. monocytogenes Treatment
    • Resistant to cephalosporin & other antibiotics
    • Antibiotics are only useful if disease is caught early