VII. IDENTIFICATION OF ATYPICAL MYCOBACTERIA
325
those of &I. tuberculosis are seen. They are distinguished from the latter by
their photochromogenic property, which is not displayed by M. tuberculosis.
'M. kansasii hydrolyses Tween-80 and reduces nitrate within five days of
inoculation and incubation at 37°C.
Freshly prepared bacterial suspensions of M . kansasii can be identified
serologically by agglutination. Older bacterial suspensions may become
unstable, showing non-specific clumping which is reduced in normal or
heterologous serum, whereas the specific agglutination remains in M .
kansasii sera. Truly rough strains of M. kansasii, however, cannot be characterised by agglutination.
The serotyping of M . kansasii is particularly helpful in the identification
of very sluggishly photochromogenic strains, non-pigmented (var. album)
or scotochromogenic variants (var. aurum) of M. kansasii. The agglutination test is also useful for the differentiation of M. kansasii from M .
marinum.
B. Mycobacterium marinum
M. marinum is the causative agent of nodular skin lesions which may
appear some weeks after scratches suffered in swimming pools (Schaefer
and Davis, 1961 ; Morgan and Blowers, 1964; Waddington, 1967), beaches
and fields (Walker et al., 1962) and after handling tropical fish aquaria
(Swift and Cohen, 1962; Adams et al., 1970; Mansson et al., 1970). It was
described first by Aronson (1926) as the cause of lesions in salt-water fish.
A similar organism was described 25 years later as the cause of skin lesions
in men acquired in a swimming pool in Sweden and named Mycobactmiurn
balnei (Norden and Linell, 1951; Linell and Norden, 1954). When both
species were later recognised as identical, M . marinum was accepted as the
official name.
M . marinum is photochromogenic. It has an optimal growth at 30-34"C,
compared to M. kansasii which grows equally well between 30 and 37°C.
The lower temperature requirement of M . marinum explains why the
organism cannot penetrate the lymph nodes or inner organs. M . marinum
hydrolyses Tween-80, but does not reduce nitrate. The two species M .
marinum and M. kansasii are rapidly differentiated by seroagglutination.
C . Mycobacterium szulgai
M. szulgai was discovered by Marks et al. (1972), by thin-layer chromatography of lipids according to Marks and Szulga (1965).
Schaefer et al. (1973a) subsequently showed strains of this species to be
antigenically identical, being agglutinated specifically by M. sxulgai
antisera.
M . szulgai is scotochmmogenic when cultured at 37"C, but photo-
325
those of &I. tuberculosis are seen. They are distinguished from the latter by
their photochromogenic property, which is not displayed by M. tuberculosis.
'M. kansasii hydrolyses Tween-80 and reduces nitrate within five days of
inoculation and incubation at 37°C.
Freshly prepared bacterial suspensions of M . kansasii can be identified
serologically by agglutination. Older bacterial suspensions may become
unstable, showing non-specific clumping which is reduced in normal or
heterologous serum, whereas the specific agglutination remains in M .
kansasii sera. Truly rough strains of M. kansasii, however, cannot be characterised by agglutination.
The serotyping of M . kansasii is particularly helpful in the identification
of very sluggishly photochromogenic strains, non-pigmented (var. album)
or scotochromogenic variants (var. aurum) of M. kansasii. The agglutination test is also useful for the differentiation of M. kansasii from M .
marinum.
B. Mycobacterium marinum
M. marinum is the causative agent of nodular skin lesions which may
appear some weeks after scratches suffered in swimming pools (Schaefer
and Davis, 1961 ; Morgan and Blowers, 1964; Waddington, 1967), beaches
and fields (Walker et al., 1962) and after handling tropical fish aquaria
(Swift and Cohen, 1962; Adams et al., 1970; Mansson et al., 1970). It was
described first by Aronson (1926) as the cause of lesions in salt-water fish.
A similar organism was described 25 years later as the cause of skin lesions
in men acquired in a swimming pool in Sweden and named Mycobactmiurn
balnei (Norden and Linell, 1951; Linell and Norden, 1954). When both
species were later recognised as identical, M . marinum was accepted as the
official name.
M . marinum is photochromogenic. It has an optimal growth at 30-34"C,
compared to M. kansasii which grows equally well between 30 and 37°C.
The lower temperature requirement of M . marinum explains why the
organism cannot penetrate the lymph nodes or inner organs. M . marinum
hydrolyses Tween-80, but does not reduce nitrate. The two species M .
marinum and M. kansasii are rapidly differentiated by seroagglutination.
C . Mycobacterium szulgai
M. szulgai was discovered by Marks et al. (1972), by thin-layer chromatography of lipids according to Marks and Szulga (1965).
Schaefer et al. (1973a) subsequently showed strains of this species to be
antigenically identical, being agglutinated specifically by M. sxulgai
antisera.
M . szulgai is scotochmmogenic when cultured at 37"C, but photo-