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Genus Clostridium. Learning objectives:. Describe the basic microbiological features of the genus Clostridium Describe clinical significance of the genus Clostridium List the most clinically important Clostridium species

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Genus Clostridium


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    1. Genus Clostridium

    2. Learning objectives: • Describe the basic microbiological features of the genus Clostridium • Describe clinical significance of the genus Clostridium • List the most clinically important Clostridium species • List the main clinical conditions caused by C. perfringens, C. tetani, C. botulinumand C. difficileand describe their major virulence factors

    3. Learning objectives: • Describe the major differences between the main clinical conditions caused by C. perfringens, C. tetani, C. botulinumand C. difficileand describe the laboratory methods used in the diagnosis of each infection • Describe in general the management of the main infections caused by genus Clostridium

    4. Clostridium • > 200 species and sub-species • Thick, Gram-positive, sporing rod • Strict anaerobes • Soil is natural habitat • GIT • Exotoxins and enzymes

    5. Medically important species • C. perfringens • Anaerobic cellulitis and gas gangrene (clostridialmyonecrosis) • C. tetani • Tetanus • C. botulinum • Botulism • C. difficile • Pseudomembranous colitis

    6. Diagnosis of clostridial infections • Identification of the pathogen • Gas gangrene • Identification of the pathogen + toxins • Tetanus, botulism and colitis

    7. Morphology and culturing • Large, Gram-positive rod • Flagellated (except C. perfringens) • Sporulated • Anaerobic atmosphere at 37°C • C. perfringenscolonies are convex, smooth, and hemolytic • Colonies of motile clostridia have an irregular edge

    8. Management • Penicillin G • Antitoxins are used in therapy of tetanus and botulism • Hyperbaric O2 is used to treat gas gangrene • The most important preventive measure against tetanus is active vaccination with tetanus toxoid

    9. Gas gangrene (clostridialmyonecrosis) Anaerobic cellulitis

    10. Pathogen spectrum • Clostridium perfringens • C. novyi • C. septicum • C. histolyticum

    11. Toxins and enzymes • Toxins: • Necrotizing, hemolytic, and/or lethal activity • Enzymes: • Collagenases, proteinases, DNases, lecithinases, and hyaluronidase

    12. Pathogenesis and clinical picture • Frequently contaminate open wounds • Types of infections: • Anaerobic cellulitis • Gas gangrene (clostridialmyonecrosis)

    13. Anaerobic cellulitis • Infection restricted to the fascial spaces that does not affect musculature • There is no toxemia

    14. Gas gangrene (clostridialmyonecrosis) • An aggressive infection of the muscles • Gas, myonecrosis and toxemia • Medical emergency

    15. Laboratory diagnosis • Specimens • Direct examination • Anaerobic culture • Identification

    16. Clostridium tetani(Tetanus)

    17. Tetanus (lockjaw) • Acute clostridial disease • Clinical manifestations caused by strong neurotoxin (tetanospasmin)

    18. Pathogenesis and clinical picture • Pathogens invade tissues following injuries • Toxin produced • Increased muscle tone and spasms

    19. Diagnosis • Toxin detection in wound material • The pathogen is difficult to culture

    20. Treatment • Anti-toxin • Wound cleaning • Muscle relaxants

    21. Clostridium botulinum(botulism)

    22. Botulism • Rare but serious paralytic illness • The toxin enters the human body in one of three ways: • Ingestion of spores (infant botulism) • Toxin ingested with food (adult botulism) • Infected wounds (wound botulism)

    23. Clostridium botulinumtoxin • Very strong neurotoxin • Heat-labile protein • Flaccid paralysis

    24. Clinical picture of classic botulism • Paralysis especially in the nerves of the head • Frequent symptoms: seeing double, difficulty swallowing and speaking, constipation, and dry mucosa

    25. Mortality and cause of death • Mortality: 25–70%, depending on the amount of toxin ingested • Death usually results from respiratory paralysis

    26. Diagnosis and treatment • Diagnosis: • Toxin detection • Therapy: • Anti-toxin

    27. Clostridium difficile(pseudomembranous colitis)

    28. Clostridium difficile • Fecal flora of 1–4% of healthy adults and in 30–50% of children during the first year of life • Pseudomembranous colitis: • Clindamycin • Aminopenicillins • Cephalosporins • Antibiotic-associated colitis

    29. Pathological mechanism • Based on formation of two toxins: • Toxin A is an enterotoxin • Toxin B is a cytotoxin

    30. Laboratory diagnosis • Isolation of the pathogen • Cytotoxin detection in stool filtrates by cytopathic effect • ELISA for toxins “A” and “B”

    31. Treatment • Not always required • Indicated only in severe cases • Metronidazole is the drug of choice