Abstract
Susceptibility of various mycobacteria to ethambutol was tested in the Löwenstein-Jensen medium. The results (Table 1) showed that the susceptibility to ethambuol be useful for differentiation of mycobacteria.
Mycobacterium terrae and scotochromogens (Runyon's group II) were susceptible to 3.13μg/ml ethambutol, while M. avium and nonphotochromogens (Runyon's group III) were resistant to this concentration of ethambutol.
Among rapid-growing mycobacteria and an intermediate form, M. thermoresistibile, and M. phlei and M. fortuitum were relatively resistant to ethambutol (Table 1). However, since the former two organisms can grow at 52°C and easily differentiated from other mycobacteria, test for ethambutol susceptibility of rapdily growing mycobacteria would be useful for detection of M. fortuitum, if the test is done in combination with the test for temperature range for growth.
