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DIRECT
WET SMEAR: Introduction
Examination
of the fecal material as a direct smear may or may not reveal
organisms; in light infections, the number of organisms present
may be very low. The direct wet smear is prepared by mixing
a small amount of stool (about 2 mg) with a drop of 0.85%
NaCl; this mixture will provide a uniform suspension under
a 22- by 22-mm coverslip. A 2-mg sample of stool forms a low
cone on the end of a wooden applicator stick. If a fresh stool
specimen is received and if blood and mucus are present, the
specimen should be examined as a direct mount making sure
to sample the bloody areas. The entire 22- by 22-mm coverslip
should be systematically examined with the low power objective
(10 x) and low light intensity; any suspicious objects may
then be examined with the high dry objective (40 x). Use
of an oil immersion objective (100 x) on wet mounts is not
routinely recommended. Many workers think that the use
of the oil immersion objective on this type of preparation
is impractical, especially since |
