STRUCTURES & COMPOSITION OF MICROORGANISMS

• Granular inclusion bodies


  Irregularly shaped circles or spheres present within the body of the organism
• Composition of granular inclusion bodies

  Accumulation of metaphosphates and polyphosphates
• Granular inclusion bodies


  • Act as energy reserve for the organism
• Microorganisms with granular inclusion bodies


  Can escape phagocytosis by using the energy reserve in the granular inclusion bodies
• Metachromasia


  A special property of granular inclusion bodies where they appear different colours from the dye used to stain them (e.g. purple/violet when stained with methylene blue)
• Volutin granules of Babes-Ernst

  The specific name for the metachromatic granules of Corynebacterium diphtheriae
• Corynebacterium diphtheriae


  • Has a "Chinese letter appearance" morphology
• Flagella


  Thin appendages/structures extending from the body of the organism, composed of the protein flagellin
• Mordant


  Reagent (tannic acid) needed to stain and demonstrate flagella
• Types of flagella classification (Messea's)

  • Monotrichous
  • Lophotrichous
  • Amphitrichous
  • Peritrichous
  • Atrichous
• Representative organisms with flagella

  • Salmonella typhi (peritrichous)
  • Pseudomonas aeruginosa (monotrichous)
• Flagella


  Structures that enable bacterial motility
• If you are asked what reagent is necessary for the demo of flagella, you would answer MORDANT
• Criteria for classifying flagella

  • Number of flagella present in organism
  • Location of the flagella in the body of the organism
• Messea's classification of flagella

  • Monotrichous - bacteria having one flagella
  • Lophotrichous - several flagella are located on one side in a tuft (bundle)
  • Amphitrichous - bacteria having flagella on each side
  • Peritrichous - flagella extending at different points
  • Atrichous - no flagella
• Representative organisms of flagella types

  • Salmonella typhi (causative agent of typhoid fever) - peritrichous
  • Pseudomonas aeruginosa - monotrichous
  • Proteus mirabilis/Proteus vulgaris (causative agent of UTI) - peritrichous
  • Vibrio cholerae - monotrichous
• Flagella


  • Motility
  • Specific antigenically
• Stains for flagella


  • Liefson's stain
  • Gray's stain
• Spores/Endospores


  Spores found within the body of the organism
• Spores/Endospores


  • Virulence factor
  • Resistance to infection
• Types of spore location

  • Central spore - in the center of the organism
  • Subterminal spore - located near the end
  • Terminal spore - located at the end portion (lollipop, tennis-racket, drumstick appearance)
• Representative organisms of spore types

  • Bacillus subtilis and Clostridium botulinum - central spore
  • Bacillus subtilis - subterminal spore
  • Clostridium tetani - terminal spore
• The virulence mechanism of spores/endospores is to RESIST DISINFECTION
• Slime layer


  Polysaccharides surrounding microorganisms in little or scanty amount
• Capsule


  Polysaccharides surrounding microorganisms in abundant or copious amount, forming a definite layer
• Slime layer or capsule

  • Virulence factor
  • Anti-phagocytic effect
• Stains for slime layer or capsule

  • Anthony stain
  • Hiss
  • Maneval's stain
• Slime layer and capsule are similar, composed of polysaccharides, but differ in the amount surrounding the microorganism
• Representative organisms


  • Slime layer - Sarcina lutea
  • Capsule - Klebsiella pneumoniae, S. pneumoniae
• Slime layer virulence mechanism


  Adhesion/adherence mechanism/attachment mechanism
• Capsule virulence mechanism


  • Prevents phagocytosis/anti-phagocytosis/anti-phagocytic effect
  • Anti-complementary
• Granular inclusion bodies


  Food reserve for the organism, also known as cytoplasmic granules or polar bodies
• Specific name for granular inclusion bodies

  Volutine granules of Babes-Ernst or Babes-Ernst granules
• Granular inclusion bodies


  • Appear as Chinese letter morphology
  • Stained by methylene blue (appear purple/violet)
• Granular inclusion bodies provide an energy reserve for the organism