CLINICAL LAB SCIENEC

392
ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
Critical Reminder
Viruses require living cells
on which to be inoculated to
achieve growth. They cannot
be placed in Petri dishes
with nutrient media such as
that designed for bacteria.
Therefore, they take more time
and effort to grow.
There are no antibiotics for
viruses. Cold and influenza
viruses are not affected to the
patient’s advantage when the
physician prescribes antibiotics.
Equipment and Supplies
1. Gloves, disposable paper towels, and disinfectant or other cleaning
solution
2. Swabs tipped with cotton or synthetic material (to be used to transfer
organisms) or reusable or sterile disposable inoculating metal loops and
needles
3. Bacterial incinerator if reusable metal loops and needles are being used,
OR sterile disposable loops and needles
4. Incubator for enhancing growth of bacteria (set at 36°C–37°C)
5. Agar plates (Petri dishes)
6. Source of organisms such as stock cultures on agar plates or in broth
(liquid media) tubes
7. Waterproof sharp marker
8. Disposal containers appropriate for biohazardous waste
Procedure
1. Wash hands and don gloves.
2. Assemble necessary equipment and supplies.
3. If reusable metal loops and needles are being used, turn on incinerator and
check that it has reached the optimum level of heat.
4. Select the proper agar plate (Petri dish) and use the marker to label it with appropriate
identifying information.
5. Introduce the sterile swab or sterilized or disposable metal loop into the broth
tube or pick up an isolated colony of bacteria from an agar plate.
6. Taking care not to touch any other surfaces
with the swab or metal loop, lift the
lid from a sterile agar plate slightly and
inoculate a fourth of the plate by rolling the
swab over the surface, taking care not to
tear the agar.
7. Replace the lid on the agar plate and
dispose of the swab in a biohazard container.
8. Streak the remainder of the agar surface
by touching the sterile loop or a
needle (this takes skill and a light touch)
to the first quadrant and streaking all the
way to the opposite side of the second
quadrant, repeating the process 7 or 8
FIGURE 15-3 Different types of nutrient media required for certain
bacterial organisms.
Source: Delmar/Cengage Learning.
times ( Figure 15-4). This serves to isolate
colonies of bacteria and to allow multiple
strains of organisms to be separated.
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