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Gram positive Bacilli

Gram positive Bacilli. Bacillus. Bacillaceae family. The genera Bacillus and Clostridium belong to the same family Spore forming bacteria Natural habitat is soil. Genus Bacillus . Gram-positive rod Obligate aerobes ( catalase positive) Ubiquitous in nature

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Gram positive Bacilli

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  1. Gram positive Bacilli

  2. Bacillus

  3. Bacillaceae family • The genera Bacillus and Clostridium belong to the same family • Spore forming bacteria • Natural habitat is soil

  4. Genus Bacillus • Gram-positive rod • Obligate aerobes (catalase positive) • Ubiquitous in nature • Both free-living and pathogenic species • Oval endospores

  5. Genus Bacillus

  6. Clinical significance • B. anthracis(anthrax) • B. cereus (food poisoning) • B. subtilisand B. coagulans(food spoiler)

  7. Morphology • Colonies are: • Usually large • Spreading • Irregular

  8. B. cereus B. anthracis

  9. Bacillus anthracis (Anthrax)

  10. Bacillus anthracis • Natural habitat soil • Anthrax is an animal infections • Anthrax is recognized as an occupational disease • Human infection by contact with: • Sick animals • Contaminated animal products

  11. Morphology and culturing • 1 µm wide and 2–4 µm long • Non-flagellated • Capsulated (a glutamic acid polypeptide)

  12. Pathogenesis of Anthrax • Anti-phagocytic capsule • Toxin (causes edemas and tissue necrosis)

  13. Types of infections • Dermal anthrax (95% of cases) • Primary inhalational anthrax • Intestinal anthrax (vomiting and bloody diarrheas)

  14. Laboratory diagnosis • Specimens should be handled in a Bio-safety level 3 facility • Gram stain shows gram-positive bacilli • In advanced disease, a gram stain of un-spun blood may be positive

  15. Identification of B. anthracis • Non-hemolytic, non-motile, capsulated bacteria • ELISA and PCR tests are available at reference laboratories

  16. Lysis of Bacillus anthracis by the lytic phage gamma

  17. Treatment • Drug of choice is penicillin G • Doxycycline or ciprofloxacin are possible alternatives

  18. End of this section

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