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An attempt was made to distinguish Mycobacterium teberculois and M. bovis from other mycobacterial species, by demonstrating cord-formation Of Mycobacteria, particu1arly tubercle bacilli, which are frequently encountered in diagnostic laboratories. A total of 71 spurum specimens with positive results and 75 strains of Mycobacteria were employed for the purpose - applied combine with Tsukamuras and Stritch-Dickinsons method. Blood media were prepared two ways which with the incorporation of p-nitrobenzoic acid(PNB 500㎍ per ml) and without PNB. Sputum smears, which were allowed to dry thoroughly, reated with IN-HCI and washed in sterile distilled water. Then the sputum smears were submerged in to the media both PNB added and without PNB respectively. After incubation at 37℃ for a week, the rides were removed out from the tube, then rinsed by distilled water and dried on hot plate for 30 minutes, and stained with Ziehl-Neelsens or fluorochrome dyes. Upon examining them by ordinary optical microscope, growing bacteria were confirme firstly and the development of cord-formation secondary. To make sure of the differentiation, the sputa were simultaneously decontaminated, inoculated, and incubated at 37℃ until the growth is seen. The cultures were then examined for niacin production in order to identify M. tuberculosis. As seen in table 1, both results obtained in this study appear to be identical in discriminating Mycobacteriun tuberculosis and M. bovis from other mycobacterial species. In conclusion, the blood medium containing p-nitrobenzoic acid can be readily used as a diagnostic aid.
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