Micro

• SAF


  Used for stool for O+P
• Sedimentation/concern


  3 stages
• Step 1: Macroscopic Examination


  1. Visual inspecting the specimen though container

  2. Colour, consistency and presence/absence of worms
• Step 2: Concentration


  1. Sedimentation method

  2. Flotation method
• Step 2: Concentration Sedimentation method

  1. Pour sample into a 15ml. centrifuge tube

  2. Add a preservative, mark and centrifuge

  3. Decant supernatant and add saline

  4. Make thick smear using Mayer's albumin

  5. Re-suspend the sediment in formalin and let it stand for 10 minutes

  6. Add 4 ml of Ethyl Acetate, cap the tube, and shake vigorously for 30 seconds

  7. Centrifuge at 10500 rpm

  8. Pipette off the four layers: Solvent, Seal, debris, and supernatant

  9. Rinse the debris pellet with saline as applicable, stain and decant the supernatant
• Step 3: Concentration Wet Mount

  1. Mix one drop of sediment with one drop of saline on a clean slide and cover with a 22 x 22 mm coverslip

  2. Scan entire area under low power for parasite eggs or larvae

  3. Add iodine to help with detection of protozoa

  4. PVA may cause precipitate, requires extra washes
• Step 4


  1. Place one drop of alanin on a clean slide

  2. After washing steps, use applicator stick to spread sediment over slide in thick and thin sections

  3. Allow to air dry and then stain
• Performing susceptible testing on organisms

  To help with treatment
• Taxonomy


  The classification of organisms into groups based on their similarities
• Taxonomy is created so that there is consistency across labs
• Binomial nomenclature


  We often refer to organisms with 2 taxonomy classifications
• Taxonomy divisions


  • Family
  • Genus
  • Species
  • Subspecies
• Family


  A group of related genera that have 1 or 2 characteristics in common
• Genus


  A group of related species that have usually 1 characteristic in common
• Species


  A group that are mostly identical
• Subspecies


  A group of organisms that are identical and may differentiate into biotypes, serotypes, and phagotypes
• Biotype


  Based on biochemical properties
• Serotype


  Based on antigenic properties
• Phagotype


  Based on susceptibility to bacterial viruses
• Family and genus


  Always capitalized
• Species


  Never capitalized
• Genus and species


  Always used together (italics if types, underlined if handwritten)
• Genus


  May be abbreviated to its first letter
• Taxonomic classification of bacteria

  • Morphological (macroscopic and microscopic)
  • Physiological (environmental requirements, nutritional requirements, biochemical properties including gram stain, enzymatic properties)
• Other bacterial classification methods

  • Numerical taxonomy
  • Antigenic properties
  • Mass spectrometry (MALDI-TOF)
  • Nucleic acid homology
• Bacterium


  The simplest living form that contains all the mechanisms necessary for growth and self replication
• Prokaryotic cells


  Cells that do not contain individual membrane-enclosed organelles
• Cytoplasmic or Cell Membrane

  Part of a bacterial cell
• Bacteria


  • Can synthesize nucleic acid, proteins, carbs, and enzymes using chemical elements like C, N, O, and H
  • Certain elements must be present for bacteria to grow, otherwise they cannot reproduce
• Organic growth factors required by bacteria

  • N from proteins
  • C from carbs and organic acids
  • Vitamins
  • Extraneous sources (co enzymes) to be used in metabolism
• Inorganic growth factors required by bacteria

  • K needed from enzyme systems
  • Iron used in respiratory system
  • Sulfur necessary for some co-enzymes
  • Phosphorus needed to make ATP and nucleic acids
• Water


  Absolutely necessary for the growth of bacteria since the cell is 80% H2O
• Water is provided through moist atmosphere of incubators and gelatinous media
• Bacteria that affects humans require isotonic environment
• pH


  A measure of acidity or alkalinity
• Bacteria that affects humans generally requires pH of 6.5-7.5
• Bacteria types by optimal temperature

  • Mesophiles grow best at 20-40 degrees C
  • Psychrophiles grow best at 10-19 degrees C
  • Thermophiles grow best at 50-60 degrees C
• Mesophiles


  • Microbes that affect humans and grow best at body temperature (37 degrees C)
• Atmospheric requirements of microbes

  • Aerobic: presence of O2
  • Obligate aerobe: absolutely require O2
  • Anaerobic: grow in absence of free O2
  • Strict anaerobic: cannot grow if more than 0.5% O2
  • Facultative: grow with or without free O2
  • Microaerophilic: grow best with reduced O2 tension
  • Capnophilic: grow best in 5-10% CO2
• Bacterial virulence factors


  Mechanisms and/or actions used by organisms to cause disease or infection