SOP 3: Baermann Technique

The Baermann technique is suitable for the isolation and identification of larvae in fresh faeces (e.g. Strongyloides spp.)

Definitions

SG       = Specific Gravity

FF        = Faecal Float

dH20    = Distilled water

Equipment set up

Secure a glass funnel to a stand and connect a rubber tube with a clamp to the stem of the funnel.

Method                                                        

  • Place 3-5 g of faeces in the centre of a large cheese cloth and tie with a rubber band or string to form a pouch
  • Place this within a tea strainer and suspend this in the funnel
  • Add warmed water to the funnel until the water covers the top of the faecal pouch
  • Leave standing for 24 hours
  • Open the stopper on the rubber tubing and collect 2 ml of the filtered sediment into a test tube
  • Leave the test-tube standing for 30 min, or alternatively centrifuge at 1000 g for 2 minutes
  • Take 1-2 drops of the sediment and place on a microscope slide with a cover slip.
  • Examine under a light microscope at low power (10 ×) for larvae

For an alternative step-by-step guide with useful images of this procedure, refer to:

http://www.rvc.ac.uk/review/parasitology/Baermann/Purpose.htm

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