Clostridia

• Clostridia


  Strictly anaerobic to aerotolerant (C. carnis, C. histolyticum, and C. tertium)

  Spore-forming bacilli

  Found in soil as well as in normal intestinal flora of man and animals

  There are both gram (+) and gram (-) species, although the majority of isolates are gram

  (+)

  • Exotoxin(s) play an important role in disease pathogenesis
• Clostridioides difficile is the most common cause of antibiotic-associated diarrheal illnesses.
• Clostridium botulinum produces neurotoxins that affect the nervous system and lead to muscle weakness or paralysis.
• 4 common species of Clostridia

  Clostridium Perfringens

  Clostridium Tetani

  Clostridium Botulinum

  Clostridium Difficile
• Clostridium tetani causes tetanus through the production of tetanospasmin.
• Clostridial wound infections are found worldwide
• Gas gangrene


  • Invasion of live tissue with systemic toxemia
  • Relatively benign superficial contamination of already necrotic tissue
• Wound infections controlled


  1. Administration of antimicrobial agents (e.g., penicillin, chloramphenicol)

  2. Tissue debridement (for more severe forms of clostridial wound infections)
• Clostridia Perfringens


  • Soil
  • Normal microbial flora of humans and animals
• Gas gangrene

  Wound infection
• Tetanus symptoms


  • Twitching of muscles around a wound, pain in neck and jaw muscles (trismus), and around the wound
  • No fever, but sweat profusely and exhibit muscle rigidity and spasms
• Clostridium tetani


  • Ubiquitous in soil
  • Occasionally found in intestinal flora of humans and animals
  • Facilitates replication and secretion of exotoxins in anaerobic tissue environment
  • Host defenses are essentially absent
  • Little, if any, innate immunity and the disease does not produce immunity in the patient
• Tetanus


  Caused only by Clostridium tetani which are bacilli with terminal pores
• Clostridium tetani

  Bacilli with terminal pores
• Tetanospasmin


  A spasmogenic toxin that fixes to inhibitory neurons and blocks the release of neurotransmitters, glycine and gamma-aminobutyric acid
• Treatment of tetanus


  1. Administration of tetanus toxoid (preventive measure)

  2. Treated with antimicrobial agents (metronidazole or penicillin) and by local wound debridement

  3. Tetanus immunoglobulin and supportive therapy
• Places tetanus is found

  • Worldwide
• Botulinum toxin


  Binds to neuromuscular junctions of parasympathetic nerves and interferes with acetylcholine release, causing flaccid muscle paralysis
• The cranial nerves are initially affected, followed by descending, symmetric paralysis of motor nerves, with critical involvement of the respiratory tree
• Clostridium botulinum


  Consists of several biochemically distinct groups of organisms that produce botulinum toxin
• Adult botulism


  Caused by ingestion of preformed toxin in food
• Infant botulism


  Organism replicates and secretes toxin in the intestinal tract
• Botulism


  Caused by C. botulinum which are oval bacilli with sub-terminal spores, distributed worldwide, and is ubiquitous in soil
• Flaccid muscle paralysis

  Muscle paralysis may occur
• The best means of control is to eliminate the toxin source via proper food handling
• Types of neurotoxins


  • A
  • B
  • C
  • D
  • E
  • F
  • G
• Wound botulism


  Organism replicates in the wound and secretes toxin
• Forms of botulism

  • Adult botulism
  • Infant botulism
  • Wound botulism
• Improper heating of canned foods is a major factor in botulism food poisoning
• Once food poisoning is diagnosed, treatment measures should include an attempt to neutralize unbound toxin
• Pseudomembranous Colitis


  Antibiotic-associated diarrhea
• Clostridium Difficile

  • Bacilli with large, oval, sub-terminal spores
  • Toxigenic and non-toxigenic strains exist
  • Toxigenic strains produce varying amounts of toxin A (enterotoxin) and toxin B (cytotoxin)
• Clostridium Perfringens


  causes food poisoning and necrotizing enteritis
• Clostridium Sordellii

  causes bacteremia, endometritis and non-bacteremic infections
• Clostridium Septicum


  Is correlated with the presence of cancer
• Clostridium Tertium


  Is associated with bacteremia
• Botulism


  3 forms: (1) Adult botulism caused by ingestion of preformed toxin in food (2) Infant botulism where the organism replicates and secretes toxin in the intestinal tract (3) Wound botulism where the organism replicates in the wound and secretes toxin
• Clostridia


  • Gram positive
  • Gram negative
  • Spore forming
  • found in soil and normal flora of the intestine of human and animals
  • Strictly anaerobic to aero tolerant
  • Rods/Bacilli
• Clostridia have clinical significance in Gas Gangrene, Botulism, Pseudomembranous Colitis, and tetanus
• Gas Gangrene is caused by anaerobic, spore-forming bacilli such as C. perfringens, C. novyi, C. septicum