I . TYPING METHODS FOR CLOSTHIDIUM
21
The strains in the Group A typing pattern are susceptible to bacteriocins
4, 28, 43, 48, 55 and 63 with variation in response to bacteriocins 75, 78
and 96. The other groups are largely defined by sensitivity to bacteriocins
4, 28 and 43. The largest percentage of strains falls into Group C (52.9%)
with types C3, 7 and 8 representing the major subgroups (Mahony, 1974).
More recently, in a survey of human faecal specimens (Mahony and Swantee, 1978), bacteriocin type C3 was the dominant type of C. perfringens
found.
It should be noted that the ability to produce bacteriocins or to be
susceptible to bacteriocins is not correlated with the classical toxin typing
scheme of the organism. Toxin types C and D were inhibited by bacteriocins produced by toxin type A strains and vice versa. This has also been
demonstrated by Sasarman and Antohi (1963, 1968,1970) for C.perfringens.
C. Variability
Under standardised conditions, the results of bacteriocin typing are
quite reproducible. Cultures should be typed as soon as possible after
isolation since repeated subculturing is undesirable for any typing system.
We have reported (Mahony, 1974) that while serially subculturing isolated
colonies ten times, and typing four colonies from each subculture a change
in the typing pattern through the loss of susceptibility to a particular
bacteriocin was occasionally noted ; however, this loss might be reversed on
further subculture. Of four strains of C. perfringens examined in this manner, only one became consistently susceptible to a bacteriocin to which it
was originally resistant. We have observed differences in typing patterns
when the organisms to be typed are plated on commercial blood plates as
opposed to those prepared in our laboratories and at present would not
recommend a departure from the methods and materials described above.
IX. POTENTIAL USE OF BACTERIOCIN TYPING
OF C. PERFRINGENS
Bacteriocin typing of C. perfringem may determine the source of clinical
infections or of food poisoning. In infections with C. perfringens the typing
patterns of the organisms isolated from the environment, from necrotic
tissue and from the patient's faeces or vagina might indicate the source of
the infection. In food poisoning outbreaks bacteriocin typing may supplement or replace serological typing of the organisms. We have looked at 12
of the Hobbs agglutinating types with respect to bacteriocin typing and
found that these strains fell into nine different bacteriocin typing patterns.
This might indicate that the antigenic typing system is more sensitive in
terms of differentiating strains.
21
The strains in the Group A typing pattern are susceptible to bacteriocins
4, 28, 43, 48, 55 and 63 with variation in response to bacteriocins 75, 78
and 96. The other groups are largely defined by sensitivity to bacteriocins
4, 28 and 43. The largest percentage of strains falls into Group C (52.9%)
with types C3, 7 and 8 representing the major subgroups (Mahony, 1974).
More recently, in a survey of human faecal specimens (Mahony and Swantee, 1978), bacteriocin type C3 was the dominant type of C. perfringens
found.
It should be noted that the ability to produce bacteriocins or to be
susceptible to bacteriocins is not correlated with the classical toxin typing
scheme of the organism. Toxin types C and D were inhibited by bacteriocins produced by toxin type A strains and vice versa. This has also been
demonstrated by Sasarman and Antohi (1963, 1968,1970) for C.perfringens.
C. Variability
Under standardised conditions, the results of bacteriocin typing are
quite reproducible. Cultures should be typed as soon as possible after
isolation since repeated subculturing is undesirable for any typing system.
We have reported (Mahony, 1974) that while serially subculturing isolated
colonies ten times, and typing four colonies from each subculture a change
in the typing pattern through the loss of susceptibility to a particular
bacteriocin was occasionally noted ; however, this loss might be reversed on
further subculture. Of four strains of C. perfringens examined in this manner, only one became consistently susceptible to a bacteriocin to which it
was originally resistant. We have observed differences in typing patterns
when the organisms to be typed are plated on commercial blood plates as
opposed to those prepared in our laboratories and at present would not
recommend a departure from the methods and materials described above.
IX. POTENTIAL USE OF BACTERIOCIN TYPING
OF C. PERFRINGENS
Bacteriocin typing of C. perfringem may determine the source of clinical
infections or of food poisoning. In infections with C. perfringens the typing
patterns of the organisms isolated from the environment, from necrotic
tissue and from the patient's faeces or vagina might indicate the source of
the infection. In food poisoning outbreaks bacteriocin typing may supplement or replace serological typing of the organisms. We have looked at 12
of the Hobbs agglutinating types with respect to bacteriocin typing and
found that these strains fell into nine different bacteriocin typing patterns.
This might indicate that the antigenic typing system is more sensitive in
terms of differentiating strains.