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.