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Gram Stain
Aka: Gram Stain, Gram Positive, Gram Negative
- Indications: Evaluation of Infection
- Acute Urethritis
- Pelvic Inflammatory Disease
- Pneumonia
- Specimens
- Infected body fluids
- Aspirated abscesses
- Exudates
- Technique
- Thin smear of material spread on slide
- Allow slide to air dry
- Fix material onto the slide
- Place side on warmer at 70 degrees Celsius or
- Pass slide through Bunsen Burner flame 3-4 times
- Overlay the slide with crystal violet for 1 minute
- Wash slide thoroughly with water
- Overlay slide with Gram Iodine for 1 minute
- Wash slide thoroughly with water
- Flood slide surface with decolorizer (acetone-Alcohol)
- Perform until no violet color washes off slide
- May require up to 10 seconds
- Wash slide completely with water
- Overlay smear with safranin counterstain for 1 minute
- Wash slide thoroughly with water
- Allow excess water to run off slide
- Allow slide to air dry or blot with bibulous paper
- Examine under high power (100x) oil immersion
- Interpretation
- Gram Positive (Stains dark blue to purple)
- Gram Positive Cocci
- Gram Negative (Stains pink to red)
- Gram Negative Rod
- Gram Negative Coccobacilli
- References
- Gulick (1983) Med Clin North Am 67:39-55 [PubMed]