Identification of mycobacteria by smear examination of the culture

Mycobacteria can be tentatively identified by the arrangement of the bacilli on smears made from the growth and stained by the Ziehl-Neelsen method. The basis of this method is the presence or absence of cords with or without loose bacilli around. Agreement of a high degree (92.7% to 97.0%) was obtained between the identification of mycobacteria by this smear technique and by the niacin test. It is recommended that this simple procedure may be used for preliminary identification, especially in developing countries.