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Gram Stain Overview

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When done properly, gram stains can provide really useful information about the patients you are working with. Review the basics and learn how to get the most out our your samples with DoveLewis Technician Jessica Waters-Miller, CVT, and Portland Community College Instructor and Technician Laura Harris, CVT.

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Jessica Waters-Miller's picture
Jessica Waters-Miller


Enrolled: 06/2013

Laura Harris's picture
Laura Harris


Enrolled: 11/2018

Content Assignment



Samantha Roderick's picture

Why was a blood smear micrograph shown? Does your facility Gram stain blood smears?

Laura Harris's picture

Hi Samantha, good question. No, we don't gram stain blood smears. The slides included around the 4 minute mark on the video were pictures provided by DoveLewis intended to illustrate the general look of bacteria. Sorry for the confusion!

Dawn Crandell's picture

Would you mind adding the details on how to heat-fix the slide? How far is slide from flame, how long to expose the slide, etc. Thanks.

Laura Harris's picture

To heat fix the slide, pass your slide, sample side UP, right over the the very top of the flame 3 times. Do not hold your slide directly over the flame for any length of time or you will ruin it; you are literally passing it over. We plan to create a separate video specifically about how to heat fix a slide. Thanks for your question, Dawn!

Janet King's picture

The description of how the bacteria Gram stain is incorrect. All bacteria stain purple with crystal violet and Gram's iodine. The difference is in the decolorizer step. Gram negative bacteria get decolorized (lose the purple color) due to higher content of lipid in the cell wall. Gram positive do not decolorize, they maintain the purple stain throughout. After decolorizing, the Gram negatives become colorless and will then pick up the pink color of the safranin.