Anaerobic culture techniques and intro to Clostridium

• What are anaerobic bacteria also known as?

  Strict anaerobes or obligate anaerobes

  
• How are the biological activities of anaerobic bacteria determined?

  By the state of oxidation of their environment
• What is the term used to express the state of oxidation?

  Oxidation-reduction or redox potential
• What do anaerobic bacteria require for viability, metabolism, and multiplication?

  Complete removal of oxygen

  
• What happens to anaerobic bacteria when exposed to oxygen?

  They produce toxic biochemical by-products

  
• Name 2 toxic by-products produced by anaerobic bacteria when exposed to oxygen.

  negatively charged superoxide radical O2-

  Hydrogen peroxide
• What is one way anaerobic bacteria obtain energy?

  Through fermentative pathways
• What properties do anaerobic bacteria lack compared to strict aerobes?

  Cytochrome system

  Certain enzymes like;

  a.catalase

  b. peroxide

  c. superoxide dismutase
• Which enzyme converts superoxide radicals to hydrogen peroxide?

  Superoxide dismutase
• What does catalase do?

  Breaks down hydrogen peroxide to water and oxygen

  
• How does the degree of oxygen intolerance vary among anaerobic bacteria?

  It varies among different bacteria species
• How are anaerobic bacteria classified?

  • Based on shape
  • Gram's stain reaction
  • Spore-formation

  
• What are the two main shapes of anaerobic bacteria?

  Bacilli and cocci
• Name a Gram-positive non-spore forming bacillus.

  Actinomyces
• Which genus is a Gram-negative non-spore former?

  Bacteroides
• What is a Gram-positive spore-forming bacillus?

  Clostridium

  
• Which Gram-negative genus includes anaerobic bacteria?

  Veillonella
• Where are strict anaerobes generally found?

  Gastrointestinal tract of animals

  
• What is a common environment for strict anaerobes?

  Soil, water, and sewage

  
• Where can anaerobic bacteria be found in humans?

  As normal flora in the mouth and intestines
• What laboratory technique is used for detecting strict anaerobes?

  Gram's stain and microscopy

  
• What is gas liquid chromatography used for?

  Detection of metabolic products
• What is Robertson’s Cooked Meat Medium used for?

  Initial inoculation of strict anaerobes

  
• What does thioglycollate medium contain?

  Sodium thioglycollate as a reducing agent
• What are the incubation methods for strict anaerobes?

  • Anaerobic jar techniques
  • GasPak or Oxoid jars
  • Other improvised methods

  
• What is a characteristic of Clostridium species?

  Most species are flagellated and motile

  
• What do spores of Clostridium species enable?

  Prolonged survival in adverse conditions

  
• Which Clostridium species is associated with gas gangrene?

  1. perfringens
• What are the main pathogenicity properties of Clostridium species?

  Ability to produce exotoxins and spores

  
• How do exotoxins contribute to Clostridium pathogenicity?

  They are major virulence factors in diseases

  
• What are the species of Clostridium associated with human diseases?

  • C. perfringens
  • C. tetani
  • C. botulinum
  • C. difficile
  • C. histolyticum

  
• Which Clostridium species is not involved in disease causation?

  1. sporogenes

  
• What enhances the transmission of pathogenic Clostridium species?

  The ability to produce spores

  
• What is the role of aggressins in Clostridium pathogenicity?

  They contribute to pathogenicity with toxins

  
• How do Clostridium species multiply in tissues?

  Without oxygen or with reduced blood supply
• What products of metabolism are detected in gas liquid chromatography?

  1. butyric acid
  2. b. propionic acid
  3. c. Oxybutyric acid
• Chances of isolation of strict anaerobes are higher in which specimens?

  Infected sites in internal organs, other tissues, cavities and fluids

  Specimens from superficial or deep wounds contaminated with dirty material including soil
• Specimens collected for isolation of strict anaerobes in internal organs, tissues and cavities and fluids include?

  1. aspirates or fluids from lungs or other tissues
  2. discharge or pus from abscesses
  3. c. infected tissues