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  • Slide 1
  • Gram positive Cocci Staphylococci Streptococci Enterococci Bacilli Bacillus Clostridia Corynebacteria
  • Slide 2
  • Overview of the medically most important gram positive bacteria
  • Slide 3
  • Slide 4
  • Slide 5
  • Slide 6
  • Genus Clostridium
  • Slide 7
  • 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. botulinum and C. difficile and describe their major virulence factors
  • Slide 8
  • Learning objectives: Describe the major differences between the main clinical conditions caused by C. perfringens, C. tetani, C. botulinum and C. difficile and describe the laboratory methods used in the diagnosis of each infection Describe in general the management of the main infections caused by genus Clostridium
  • Slide 9
  • Clostridium > 200 species and sub-species Thick, Gram-positive, sporing rod Strict anaerobes Soil is natural habitat GIT Exotoxins and enzymes
  • Slide 10
  • Medically important species C. perfringens Anaerobic cellulitis and gas gangrene (clostridial myonecrosis) C. tetani Tetanus C. botulinum Botulism C. difficile Pseudomembranous colitis
  • Slide 11
  • Diagnosis of clostridial infections Identification of the pathogen Gas gangrene Identification of the pathogen + toxins Tetanus, botulism and colitis
  • Slide 12
  • Morphology and culturing Large, Gram-positive rod Flagellated (except C. perfringens) Sporulated Anaerobic atmosphere at 37C C. perfringens colonies are convex, smooth, and hemolytic Colonies of motile clostridia have an irregular edge
  • Slide 13
  • Management Penicillin G Antitoxins are used in therapy of tetanus and botulism Hyperbaric O 2 is used to treat gas gangrene The most important preventive measure against tetanus is active vaccination with tetanus toxoid
  • Slide 14
  • Gas gangrene (clostridial myonecrosis) Anaerobic cellulitis
  • Slide 15
  • Pathogen spectrum Clostridium perfringens C. novyi C. septicum C. histolyticum
  • Slide 16
  • Toxins and enzymes Toxins: Necrotizing, hemolytic, and/or lethal activity Enzymes: Collagenases, proteinases, DNases, lecithinases, and hyaluronidase
  • Slide 17
  • Pathogenesis and clinical picture Frequently contaminate open wounds Types of infections: Anaerobic cellulitis Gas gangrene (clostridial myonecrosis)
  • Slide 18
  • Anaerobic cellulitis Infection restricted to the fascial spaces that does not affect musculature There is no toxemia
  • Slide 19
  • Gas gangrene (clostridial myonecrosis) An aggressive infection of the muscles Gas, myonecrosis and toxemia Medical emergency
  • Slide 20
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  • Laboratory diagnosis Specimens Direct examination Anaerobic culture Identification
  • Slide 22
  • Slide 23
  • Clostridium tetani (Tetanus)
  • Slide 24
  • Tetanus (lockjaw) Acute clostridial disease Clinical manifestations caused by strong neurotoxin (tetanospasmin)
  • Slide 25
  • Pathogenesis and clinical picture Pathogens invade tissues following injuries Toxin produced Increased muscle tone and spasms
  • Slide 26
  • Diagnosis Toxin detection in wound material The pathogen is difficult to culture
  • Slide 27
  • Slide 28
  • Treatment Anti-toxin Wound cleaning Muscle relaxants
  • Slide 29
  • Clostridium botulinum (botulism)
  • Slide 30
  • 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)
  • Slide 31
  • Clostridium botulinum toxin Very strong neurotoxin Heat-labile protein Flaccid paralysis
  • Slide 32
  • 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
  • Slide 33
  • Mortality and cause of death Mortality: 2570%, depending on the amount of toxin ingested Death usually results from respiratory paralysis
  • Slide 34
  • Diagnosis and treatment Diagnosis: Toxin detection Therapy: Anti-toxin
  • Slide 35
  • Clostridium difficile (pseudomembranous colitis)
  • Slide 36
  • Clostridium difficile Fecal flora of 14% of healthy adults and in 3050% of children during the first year of life Pseudomembranous colitis: Clindamycin Aminopenicillins Cephalosporins Antibiotic-associated colitis
  • Slide 37
  • Pathological mechanism Based on formation of two toxins: Toxin A is an enterotoxin Toxin B is a cytotoxin
  • Slide 38
  • Laboratory diagnosis Isolation of the pathogen Cytotoxin detection in stool filtrates by cytopathic effect ELISA for toxins A and B
  • Slide 39
  • Treatment Not always required Indicated only in severe cases Metronidazole is the drug of choice