CLINICAL LAB SCIENEC

398
ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
3. Place the slide(s) prepared in Procedure #2
on a staining rack positioned over a sink to
permit draining of the solutions (Figure 15-8).
4. Flood the slide with crystal violet.
5. After 30 seconds to a minute, gently wash
the slide with clean tap or deionized water,
using a weak stream of water.
6. Return the slide to the staining rack.
7. Flood the slide with Gram’s iodine.
8. After 30 seconds to a minute, again gently
wash the slide with clean tap or deionized
FIGURE 15-8 Slides staining on rack designed for Gram staining. water, using a weak stream of water.
Source: Delmar/Cengage Learning.
9. Holding the slide at a 30- to 40-degree
angle over the sink, quickly decolorize the
slide’s contents by flooding the slide briefly
(10 seconds) with an acetone-alcohol
mixture (do not over-decolorize the slide—
only a few seconds are required for this
process). All color will run from a slide
containing predominantly Gram-negative
organisms.
10. Briefly rinse the decolorizer from the slide with a weak stream of clean tap or
deionized water, then drain the water from the slide briefly. Return the slide to the
staining rack.
11. Flood the slide with a counterstain of safranin.
12. Rinse the slide gently with tap water and place in a vertical position in a slotted
rack designed for standing slides on their ends.
13. Gently blot the slide dry with the bibulous paper before examining it under a
microscope.
14. Discard all supplies used for the procedure in the appropriate containers.
A disinfectant should be used to clean the work surfaces and equipment should
be cleaned and restored to its former position. Gloves should be discarded
appropriately and the hands washed thoroughly in accordance with established
policies.
Reporting of Results
The smear is read microscopically using the oil-immersion objective. Results are
reported as either Gram-positive or Gram-negative, and as rods (rod-shaped organisms)
or as cocci (spherical in shape). Sometimes rod-shaped organisms that are
extremely short are reported as coccobacilli. Some species of cocci occur in pairs
and are called diplococci.
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