324
W. B. SCHAEFER
tentatively classified into four groups: I, photochromogens ; 11, scotochromogens; 111, non-photochromogens; and IV, rapid growers (Runyon,
1959).
A more precise classification into species with common cultural and biochemical properties confirmed by numerical analysis of many strains has
been developed (Meissner, 1974).
Serological techniques have also been used as tools for identification.
The most discriminating and useful test is the seroagglutination test
(Schaefer, 1965). This test is applicable only to smooth colony-forming
mycobacteria. The majority of the atypical mycobacteria are of this colony
form. The seroagglutination test is based on the presence of species- or
type-specific antigens on the surface of the smooth colony-forming bacteria. Rough colony variants do not have these antigens. Suspensions of
rough strains are usually unstable and unsuitable for the agglutination test.
Mycobacterium tuberculosis and Mycobacterium bovis form only rough
colonies and cannot be identified by the seroagglutination test.
The methodology of the seroagglutination test will be described in detail
and findings shedding some light on the ecology and epidemiology of the
atypical mycobacteria will be presented. Results obtained with other
immunological tests will also be reviewed. It should be pointed out that
the seroagglutination test can be profitably applied only after the strains
have been classified by their cultural and biochemical properties. The
characteristics of the various species will be described and it will be indicated whether the seroagglutination test is applicable to them or not.
11. CLASSIFICATION O F T H E ATYPICAL MYCOBACTERIA
A. Mycobacterium kansasii
M. Kansasii, was described by Buhler and Pollock (1953) as the cause of
pulmonary disease indistinguishable from tuberculosis, and called “the
yellow bacillus”. The name was later changed to M . Kansasii. The colonies
of this species become visible within two weeks of inoculation and incubation at 37°C. They are non-pigmented when grown in the dark, but become
yellow when left in daylight for one or two days. T o observe the colour
change it is preferable to leave the cultures in daylight for a few hours and
reincubate them at 37°C overnight. After the reincubation the yellow colour
is fully developed. The phenomenon of colour change after exposure to
light is called photochromogenicity.
Colonies of M . Kansasii grown on oleic acid-albumin medium are smooth,
slightly wrinkled and with undulate edges. They can be identified by this
characteristic appearance. Sometimes only rough colonies resembling
W. B. SCHAEFER
tentatively classified into four groups: I, photochromogens ; 11, scotochromogens; 111, non-photochromogens; and IV, rapid growers (Runyon,
1959).
A more precise classification into species with common cultural and biochemical properties confirmed by numerical analysis of many strains has
been developed (Meissner, 1974).
Serological techniques have also been used as tools for identification.
The most discriminating and useful test is the seroagglutination test
(Schaefer, 1965). This test is applicable only to smooth colony-forming
mycobacteria. The majority of the atypical mycobacteria are of this colony
form. The seroagglutination test is based on the presence of species- or
type-specific antigens on the surface of the smooth colony-forming bacteria. Rough colony variants do not have these antigens. Suspensions of
rough strains are usually unstable and unsuitable for the agglutination test.
Mycobacterium tuberculosis and Mycobacterium bovis form only rough
colonies and cannot be identified by the seroagglutination test.
The methodology of the seroagglutination test will be described in detail
and findings shedding some light on the ecology and epidemiology of the
atypical mycobacteria will be presented. Results obtained with other
immunological tests will also be reviewed. It should be pointed out that
the seroagglutination test can be profitably applied only after the strains
have been classified by their cultural and biochemical properties. The
characteristics of the various species will be described and it will be indicated whether the seroagglutination test is applicable to them or not.
11. CLASSIFICATION O F T H E ATYPICAL MYCOBACTERIA
A. Mycobacterium kansasii
M. Kansasii, was described by Buhler and Pollock (1953) as the cause of
pulmonary disease indistinguishable from tuberculosis, and called “the
yellow bacillus”. The name was later changed to M . Kansasii. The colonies
of this species become visible within two weeks of inoculation and incubation at 37°C. They are non-pigmented when grown in the dark, but become
yellow when left in daylight for one or two days. T o observe the colour
change it is preferable to leave the cultures in daylight for a few hours and
reincubate them at 37°C overnight. After the reincubation the yellow colour
is fully developed. The phenomenon of colour change after exposure to
light is called photochromogenicity.
Colonies of M . Kansasii grown on oleic acid-albumin medium are smooth,
slightly wrinkled and with undulate edges. They can be identified by this
characteristic appearance. Sometimes only rough colonies resembling