II. Indications: Evaluation of Infection

III. Specimens

  1. Infected body fluids
  2. Aspirated abscesses
  3. Exudates

IV. Technique

  1. Thin smear of material spread on slide
    1. Allow slide to air dry
  2. Fix material onto the slide
    1. Place side on warmer at 70 degrees Celsius or
    2. Pass slide through Bunsen Burner flame 3-4 times
  3. Overlay the slide with crystal violet for 1 minute
  4. Wash slide thoroughly with water
  5. Overlay slide with Gram Iodine for 1 minute
  6. Wash slide thoroughly with water
  7. Flood slide surface with decolorizer (acetone-Alcohol)
    1. Perform until no violet color washes off slide
    2. May require up to 10 seconds
  8. Wash slide completely with water
  9. Overlay smear with safranin counterstain for 1 minute
  10. Wash slide thoroughly with water
    1. Allow excess water to run off slide
  11. Allow slide to air dry or blot with bibulous paper
  12. Examine under high power (100x) oil immersion

V. Interpretation

  1. Gram Positive (Stains dark blue to purple)
    1. Gram Positive Cocci
  2. Gram Negative (Stains pink to red)
    1. Gram Negative Rod
    2. Gram Negative Coccobacilli

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Ontology: Bacterial stain, routine (C0200966)

Definition (NCI) This is a method (named after the Danish bacteriologist, Hans Christian Gram) for staining and identifying bacteria. It is based on the differential retention of a crystal violet-iodine complex within the cell membrane. Gram-positive organisms will appear blue-black or purple while Gram-negative organisms will appear red.
Definition (NCI_CDISC) A microscopy staining method for staining and identifying bacteria, based on the differential retention of a crystal violet-iodine complex within the cell membrane. Gram-positive organisms will appear blue-black or purple while Gram-negative organisms will appear red.
Concepts Laboratory Procedure (T059)
SnomedCT 62777006
LNC LP6301-8
English Bacterial stain, routine, gram's stain, gram stain, GRAM STAIN, Gram stain, Gram stain method (procedure), Gram stain method, Gram stain (procedure), Gram Staining Method
Italian Colorazione di Gram
Japanese グラム染色, グラムセンショク
Spanish tinción de Gram, tinción bacteriana, de rutina, Tinción de Gram, tinción de Gram (procedimiento), método de tinción de Gram (procedimiento), método de tinción de Gram
Czech Gramovo barvení
Hungarian Gram festés
Portuguese Coloração de Gram
Dutch Gramkleuring
French Coloration de Gram
German Gram-Faerbung