Abstract
Microscopic observations of the morphology of mycobacteria after the Ziehl-Neelsen stain serve for differentiation among mycobacterial species. Rapidly growing mycobacteria were cultivated on Ogawa egg medium slants at 37°C for 5 days, and slowly growing ones for 14 days. The organisms grown were observed after staining by the Ziehl-Neelsen method. Useful morphological characteristics were the occurences of long rods (longer than 7μ), coccoids, and cross-barring (intracellular granules).
Within Group I, the majority of strains of M. kansasii show long rods with cross-barring, whereas M.marinum strains show these features relatively rarely.
Within Group II, the occurence of long rods with cross-barring is rare in M. scrofulaceuin strains, whereas the majority of strains of M.szulgai and M.gordonae show cross-barred long rods.
Within Group III, M.avium-intracellulare complex appears usually as short rods or intermediate rods without cross-barring, whereas long rods and cross-barring are not rare in M. nonchrornogenicum complex and M. gastri.
M.simiae and M.asiaticum are differentiated from each other by their morphological characteristics (Tables 2 and 4).
Among rapidly growing mycobacteria, only the strains of M.duvalii and M.tokaiense show cross-barring, and only M.chitae and M.chubuense appear as only coccoids.
