BACTERIOLOGY <<Back
 
 
148
EVALUATION OF SPUTUM SMEARS PREPARED BY DIFFERENT METHODS
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, CENTRIFUGATION, EVALUATION.

151
RECOVERY OF TUBERCLE BACILLI FROM URINE OF PULMONARY TUBERCULOSIS PATIENTS AND ITS COMPARISON WITH THE CORRESPONDING SPUTUM ISOLATES
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 pulmonary tuberculosis.

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.
 
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