Single Slide Automated Gram Stainer User Manual
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IFU/Manual - 8"Wx10"H
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AMS1800062
Rev. 0 2018-06
1.0 INTRODUCTION
This Operation Manual is provided to guide the user in all aspects of unit set-up, operational use, and user-level maintenance of the Cardinal Health™ Single Slide
Automated Gram Stainer unit.
The Single Slide Automated Gram Stainer is a microscope slide stainer capable of automatically performing a Gram stain sequence on a slide containing biological
specimen for
in vitro
diagnostic use. An on-board computer, running software specially designed to accomplish correct Gram stain results for any type of sample,
controls the entire staining process.
The Single Slide Automated Gram Stainer software provides a series of menus for operator control of the unit. By pressing a key corresponding to a menu item,
the operator directs program flow to the various logic paths of the software. All program functions are accessed in this manner.
Operator Responsibility – Safety Instructions
The Single Slide Automated Gram Stainer ensures safe operation when installed, operated, and maintained according to common safety regulations.
This section describes the potential dangers that may arise when operating the Single Slide Automated Gram Stainer.
It is the operator’s responsibility to be properly qualified to operate the Single Slide Automated Gram Stainer. The operator and personnel are also advised to
refer to this Operating Manual and the set-up letter that is packaged with the unit. If you require additional assistance, please call (800) 266-2222 (ext. 2) to be
connected with Cardinal Health™ Technical Support serviced by QuickSlide™.
In addition, the operator is to be familiar with good laboratory practices and safety precautions.
Explanation of Symbols
I
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Power On
O
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Power Off
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Caution:
Refer to marked paragraphs
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Not Made with Natural Rubber Latex
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In Vitro Diagnostic Medical Device
Background – Gram’s Staining Technique
The Gram staining method, named after Hans Christian Gram, the Danish bacteriologist who originally devised it in 1882, is one of the most important
staining techniques in microbiology. It is usually the first test performed for the presumptive identification of bacteria. The primary stain of the Gram’s method
consists of staining with crystal violet which is then fixed with iodine. The microorganisms that retain the crystal violet-iodine complex appear purple under
microscopic examination and are commonly classified as Gram positive. Others that are not stained by crystal violet, due to a decolorization, step are referred to
as Gram negative, and appear red as a result of counter-staining with safranin.
Gram staining is based on the ability of the bacteria cell wall to retain the crystal violet dye during treatment with acetone-alcohol. The cell wall for Gram positive
microorganisms have a higher peptidoglycan and lower lipid content than Gram negative bacteria. Bacteria cell walls are stained by the crystal violet. Iodine is then
added as a mordant to form the crystal violet-iodine complex so that the dye cannot be removed easily. Subsequent treatment with an acetone-alcohol decolorizer,
which is a solvent, dissolves the lipid layer from the Gram negative cells. The removal of the lipid layer enhances the leaching of the primary crystal violet stain
from the cells into the surrounding solvent. In contrast, the solvent dehydrates the thicker Gram positive cell walls, closing the pores as the cell wall shrinks during
dehydration. As a result, the diffusion of the violet-iodine complex is blocked, and the bacteria remain stained purple. The length of the decolorization step is
critical in differentiating the Gram positive bacteria from the Gram negative bacteria. A prolonged exposure to the decolorizing agent will remove all the stain
from both types of bacteria. Some Gram positive bacteria may lose the stain easily and, therefore, appear as a mixture of Gram positive and Gram negative bacteria
(Gram variable). Finally, a counter-stain of safranin is applied to the smear to give decolorized Gram negative bacteria a red or pink color.
The decolorization step is especially critical and must be timed correctly; the crystal violet stain is removed from both Gram positive and negative cells if the
decolorizing agent is left on too long. This can be particularly problematic for smears of varying thickness – thicker smears require longer exposure for proper
decolorization than thinner smears. This is the most sensitive and variable step of the procedure, and requires experience to know just how much to decolorize
manually. Many labs performing manual Gram stains have considerable quality control problems for this reason.
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