VII. IDENTIFICATION OF ATYPICAL MYCOBACTERIA
337
method they were able to determine which of the antigens were present in
a tuberculin preparation and their relative amounts.
Some insight into the distribution of the serotypes of M . avium, M .
intracellulare, and M . scrofulaceum has been gained from an investigation of
strains isolated from human sources in Wales, New South Wales and the
U.S.A. (Table 111) during the last five years (Schaefer, unpublished
results).
Table I1 shows that a total of 757 strains was studied and that 73.8% of
the strains were identified serologically. The unclassified strains were either
rough or belonged to serotypes not represented in the serotyping procedure.
It is of interest that the strains of clinical significance from Wales (repeated
sputum isolations and strains from cervical lymph nodes) and those from
New South Wales (cervical lymph nodes) gave a higher percentage of
typeable strains (86.7, 84-5 and 78.0%) than the strains from the U.S.A.,
the origin of which was often unknown (66.2 and 73.5%).
It appears from this study that the 23 serotypes used in the typing procedure (type 5 was excluded because of its rarity) identified nearly 75% of
the strains from human sources. Some regional differences in type distribution were observed: M . avium type 2 in Wales accounted for 12.5% of all
isolates from sputa or lymph nodes but in the U.S.A. only for 2%.
M . avium 2 in Wales was 2.9 times more frequent than M . avium 1,
whereas in the U.S.A. M . avium 1 was 3.7 times more frequent than
M. avium 2.
The M . scrofulaceum types (41-43) from Wales accounted for 9.8% of
the isolates from cervical lymph nodes, whereas in New South Wales they
accounted for 47.6%.
A study of 77 strains isolated in Japan from patients with pulmonary
disease (Nemoto et al., 1975) indicated that 26 (33.8%) were untypable
because of spontaneous agglutination. Five belonged to the M . scrofulaceum
types and 46 to the M. avium-M. intracellulare complex. Only one strain
of M . avium 1 and no strains of M. avium 2 were found.
VII. EPIDEMIOLOGY
M . avium, especially M . avium 2, is undoubtedly the type which is most
pathogenic and most easily transmitted to other animals (Schaefer, 1968).
The source of infection is usually an old tuberculous chicken with open
intestinal lesions the content of which is shed with the faeces on to the soil
where these bacteria can persist for many years. The bacteria are picked
up from the soil by other domestic animals such as chickens, cattle, and
swine. The infection thus, because of the persistence of the bacteria in the
soil, easily becomes endemic. M . avium 1 plays a similar role, but type 1
12
337
method they were able to determine which of the antigens were present in
a tuberculin preparation and their relative amounts.
Some insight into the distribution of the serotypes of M . avium, M .
intracellulare, and M . scrofulaceum has been gained from an investigation of
strains isolated from human sources in Wales, New South Wales and the
U.S.A. (Table 111) during the last five years (Schaefer, unpublished
results).
Table I1 shows that a total of 757 strains was studied and that 73.8% of
the strains were identified serologically. The unclassified strains were either
rough or belonged to serotypes not represented in the serotyping procedure.
It is of interest that the strains of clinical significance from Wales (repeated
sputum isolations and strains from cervical lymph nodes) and those from
New South Wales (cervical lymph nodes) gave a higher percentage of
typeable strains (86.7, 84-5 and 78.0%) than the strains from the U.S.A.,
the origin of which was often unknown (66.2 and 73.5%).
It appears from this study that the 23 serotypes used in the typing procedure (type 5 was excluded because of its rarity) identified nearly 75% of
the strains from human sources. Some regional differences in type distribution were observed: M . avium type 2 in Wales accounted for 12.5% of all
isolates from sputa or lymph nodes but in the U.S.A. only for 2%.
M . avium 2 in Wales was 2.9 times more frequent than M . avium 1,
whereas in the U.S.A. M . avium 1 was 3.7 times more frequent than
M. avium 2.
The M . scrofulaceum types (41-43) from Wales accounted for 9.8% of
the isolates from cervical lymph nodes, whereas in New South Wales they
accounted for 47.6%.
A study of 77 strains isolated in Japan from patients with pulmonary
disease (Nemoto et al., 1975) indicated that 26 (33.8%) were untypable
because of spontaneous agglutination. Five belonged to the M . scrofulaceum
types and 46 to the M. avium-M. intracellulare complex. Only one strain
of M . avium 1 and no strains of M. avium 2 were found.
VII. EPIDEMIOLOGY
M . avium, especially M . avium 2, is undoubtedly the type which is most
pathogenic and most easily transmitted to other animals (Schaefer, 1968).
The source of infection is usually an old tuberculous chicken with open
intestinal lesions the content of which is shed with the faeces on to the soil
where these bacteria can persist for many years. The bacteria are picked
up from the soil by other domestic animals such as chickens, cattle, and
swine. The infection thus, because of the persistence of the bacteria in the
soil, easily becomes endemic. M . avium 1 plays a similar role, but type 1
12