|INTER & INTRA-READER VARIATIONS IN DIRECT MICROSCOPY
AND THEIR INFLUENCE ON SENSITIVITY & SPECIFICITY
|K Padmanabha Rao: Proceed 24th Natl TB & Chest
Dis Workers Conf, Trivandrum, 1969, 99-110.
A study was done to evaluate inter and intrareader
differences in reading of smears stained by Fluorescent Method (FM)
and Modified ZN Staining (CS) methods and variation in multiple
smears made from the same specimens in order to find out to what
extent sensitivity and specificity are influenced by repeated sputum
smears from same specimens, by change of readers or by repeated
Eighty sputum specimens with known results, 35
negative and 45 positive with different grades were selected. Ten
smears were prepared from each specimen. All the smears were first
examined by FM and later by CS method. Culture was also done for
these specimens. The findings were: (i) FM was more sensitive
than CS method. The specificity appeared to be equal in both.
(ii) Change of readers influenced the relative sensitivity of both
methods, but repeated examination by the same reader had no effect.
(iii) Both reader as well as reading influenced the specificity
of FM method but not that of CS method. (iv) Repeated sampling from
the same specimen had no effect on the sensitivity of both the methods,
while it had some effect on the specificity of FM method. (v) Consistency
among readers and readings was found to be poor in smears with low
grade positivity. (vi) The relative sensitivity of any method was
influenced by the proportion of low grade positive cultures in the
total pool. (vii) Examination of multiple smears from the same specimen
by more than one reader and more than one reading by the same reader
was more rewarding in CS method.
|KEY WORDS: SPUTUM EXAMINATION, SENSITIVITY,
SPECIFICITY, MODIFIED ZIEHL1-NEELSEN, FLUORESCENT.
|RECOVERY OF TUBERCLE BACILLI FROM URINE OF PULMONARY
TUBERCULOSIS PATIENTS AND ITS COMPARISON WITH THE CORRESPONDING SPUTUM
|VK Challu, B Mahadev, R Rajalakshmi & K Chaudhuri:
Indian J TB 1989, 36, 107-11.
A study was done to compare (1) the filtration
method with conventional centrifugation method for the recovery
of tubercle bacilli from urine and (2) drug sensitivity profile,
virulence for guinea pigs and phage type of the urine isolates with
the corresponding isolates from the sputum of cases of bacillary
Urine specimens from 236 pulmonary tuberculosis
patients were cultured by routine centrifugation method as well
as filtration method. Filtration was done by passing urine through
a 0.45 um membrane filter and treating the membrane with 5% oxalic
acid for 15 minutes. LJ medium was used for culture in both the
methods. Centrifugation yielded 27 positives (11.6%) whereas
filtration gave 12 (12.6%) out of 95 specimens filtered. Contamination
was more with filtration method. Comparison of the biological
properties of M.tuberculosis isolated from urine and sputum of the
same patients revealed difference in drug sensitivity profile or
virulence for guineapigs for 13 of 25 (52%) of the pairs of isolates
tested. Moreover 4 of 11 pairs subjected to phage typing were found
to differ in both major and minor phage types. The significance
of these findings in the light of the pathogenesis of tuberculosis
is also discussed.
|KEY WORDS: FILTRATION, CENTRIFUGATION, SENSITIVITY,
VIRULENCE, SPECIFICITY, TUBERCLE BACILLI.
|SERODIAGNOSIS OF PULMONARY TUBERCULOSIS BY KAOLIN
|Sujatha Chandrasekaran, EV Venkataramana Gupta, MM
Chauhan, GVJ Baily, K Chaudhuri: Indian J TB 1990, 37, 11-15.
The limitation of microscopy, culture and radiology
in the diagnosis of tuberculosis, especially smear negative and
extra pulmonary, are well known. Hence, attempts have been going
on to find a suitable serodiagnostic test. One such test was based
on Kaolin Agglutination using tuberculo phosphatide as antigen.
A study was done to find out the usefulness of this test in the
diagnosis of pulmonary tuberculosis. Serum specimens from 297 newly
diagnosed tuberculosis patients and 208 healthy controls, were subjected
to Kaolin Agglutination Test (KAT) using tuberculo phosphatide as
antigen. Of the 297 X-ray positives, 184 were sputum smear positive
and 237 were culture positive for M.tuberculosis. A titre of >=
16 was taken to be diagnostic.
The test picked up 53.6 percent of the culture
positives and 54.0 percent of the microscopy positives correctly.
Also, 48.8 percent of the X-ray positives and 14.2 percent of the
healthy controls were found positive. The overall sensitivity
of KAT was 53.6 percent and specificity 85.8 percent which does
not make the test suitable for diagnosis of tuberculosis.
|KEY WORDS: SERODIAGNOSIS, SENSITIVITY, SPECIFICITY,
KAOLIN AGGLUTINATION TEST, CASE-FINDING TOOL.