328
W. B. SCHAEFER
Serological study of M. avium and M . intracellulare revealed that the
avian strains belonged almost exclusively to two types: 1 and 2. Type 2
predominates (Schaefer, l965). Later a type 3 was discovered in England
(Marks et al., 1969); this has now also been found frequently on the European continent.
M . intracellulare isolated from human patients and domestic animals has
belonged to a variety of serotypes other than M. avium. These types were
at first designated by Roman numerals, or personal names. At present they
are designated by Arabic numbers beginning with 4 (Table I) (Wolinsky
and Schaefer, 1973).
While M. intracellulare in general is avirulent, strains of the serotypes 4,
5, 6, 8, and 9 exhibit a marked virulence upon intravenous injection (Anz
and Meissner, 1972). This group was therefore designated as the “intermediate” group. On the other hand, there are also attenuated and avirulent
strains of M . avium. The loss of virulence in M . avium may accompany a
change from the T to the D form. It has been shown that the T forms are
virulent whereas the D colonies isolated from the same strains are avirulent
(Schaefer et al., 1970; Anz and Meissner, 1972).
T:ABLE I
Numbering system for the serotypes of the M . avium complex
Old designation
New designation
M . avium
1, 2, 3
M. intracellulare
IV
V
VI
VI I
Davis
Watson
IIIa
IIIb
Howell
Chance
Boone
Dent
Yandle
Wilson
Altmann
Darden
Arnold
Lunning
Gause
M. scrofulaceum
Scrofulr ceum
1, 2, 3
4
5
6
7
8
9
10
11
12
1 3
14
15
16
17
18
19
20
41
42
43