How to Do a Gram Stain Slide at Home

The gram stain test is used to determine the presence or absence of bacteria. If bacteria are present, this microscopic test divides them into gram-negative and gram-positive organisms. A violet colored stain is used when preparing the gram stain slide. This stain will dye gram-positive bacteria purple and gram-negative bacteria pink. Using a microscope, other details, such as size, shape and quantity of the bacteria, are also viewed. Results of the gram stain test assist your health care provider in diagnosing and treating your condition. To obtain accurate results, the gram stain slide must be prepared correctly, and you can learn to create your own gram stain slide to perfect your technique at home.

Things You'll Need

• Glass microscope slide
• Latex gloves
• Water (tap or distilled)
• Bacteria sample
• Sterile cotton swab
• Watch with a second hand
• Crystal violet stain
• Iodine
• Decolorizing solution (Acetone/Ethanol)
• Safranin stain
• Microscope (optional)

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Instructions

• 1

  Place a bacteria sample onto your microscope slide. This can be done by using a prepared bacteria sample or collecting a sample from your mouth. When using a prepared culture medium, place one drop of bacteria onto your slide. To collect your own sample, swipe a cotton-tipped swab around the inside of your mouth. Wipe the fluid collected onto your slide. Whichever type of sample you use must be smeared onto the slide, using a circular motion. Only a small amount of bacterial medium is needed and your bacterial specimen should be just under 2 cm. in diameter, after smearing. Allow the medium to air dry. Always wear latex gloves when handling bacteria.

• 2

  Cover your prepared bacteria with crystal violet stain. Allow the stain to remain on the slide for 60 seconds, then rinse with water. Allow the slide to air dry.

• 3

  Pour iodine onto the slide and allow it to sit for 60 seconds. Rinse with water and allow the slide to air dry.

• 4

  Trickle enough decolorizer solution onto your slide to cover it completely. Allow it to sit for only five seconds before rinsing off with water. Allow it to air dry.

• 5

  Cover your slide with safranin stain and allow it to sit for 90 to 120 seconds. Rinse with water and allow the slide to air dry.

• 6

  Shake the excess water off of your slide and allow it to air dry.

• 7

  View your gram stain slide under a microscope and note the different shapes and colors of the organism you see. For official diagnostic purposes, an experienced laboratory technician should evaluate your slide.