|EVALUATION OF SPUTUM SMEARS PREPARED BY DIFFERENT
|N Naganathan, KT Ganapathy & R Rajalakshmi: Indian
J Med Res 1979, 69, 893-900.
Sputum microscopy is the main casefinding tool
in tuberculosis control programmes. The technique of smear preparation
is an important step which needs to be simple for wide applicability.
It is often stressed that smear should be prepared from the purulent
portions of the sputum as they are likely to have more number of
bacilli. It may not be possible for the microscopist/paramedical
worker at the periphery to strictly follow this procedure. Hence,
a study was conducted to compare the sensitivity of 4 methods of
sputum smear preparation viz., direct smear prepared (i) blindly
without making any selection of portions of sputum specimen, (ii)
from portions of sputum material likely to contain the bacilli,
(iii) after mixing up the sputum specimens thoroughly, and (iv)
from centrifuged deposit after homogenization of sputum with sodium
hydroxide and concentration by centrifugation. Culture was also
done for Mycobacterium tuberculosis.
A total of 549 specimens were employed. Positivity
rates by four methods were: 79.6% by method (i), 80.3% by method
(ii), 80.7% by method (iii) and 77.2% by method (iv). There was
no statistically significant difference in the number of positives
obtained from different methods. Centrifuged deposit smears proved
to be in no way better than the direct smears. The differences
in the methods lay only in the classification of positive smear
as of a low or high grade.
|KEY WORDS: SMEAR EXAMINATION, SENSITIVITY METHODS,