SOP 4: Sedimentation Technique

The faecal sedimentation technique is suitable for the isolation and identification of heavier eggs, especially those of flukes (e.g. Paragonimus spp.) The method is quick, inexpensive and does not require the use of a centrifuge

Definitions

SG       = Specific Gravity

FF        = Faecal Float

dH20    = Distilled water

Method                                                     

  • Soak 5 g faeces in 50 ml dH20 and mix thoroughly
  • Pass through tea strainer into a plastic jar to filter
  • Pour all contents into a conical test tube (50 ml)
  • Allow to sediment for 5 minutes
  • Pour off supernatent
  • Pour sediment into a 10-15 ml conical test tube
  • Allow to sediment 5 min
  • Pour off supernatant carefully
  • Can add 1 or 2 drops of 5% aqueous methylene blue solution in test tube to aid in identification (yellow or colourless fluke eggs against a blue background)
  • Transfer 1-2 drop of the sediment to a microscope slide, place a cover slip and examine using a light microscope under low power (4× and 10×)

Safety Precautions

  • Wear lab coat and disposable gloves
  • Wash hands thoroughly when finished

Clean Up Procedures

  • Dispose of all slides and cover slips in a sharps container
  • Clean all equipment (tea strainer, glass test tubes) thoroughly with a 10% bleach solution
  • Wipe down work area with 70% Ethanol.