2
D. E. MAHONY
same species, under appropriate conditions, are capable of causing destructive and sometimes fatal disease such as botulism, gas gangrene, clostridial
cellulitis, tetanus and the non-fatal but frequently encountered Clostridium
perfringens food poisoning. Because such organisms are ubiquitous, the possible typing of these bacteria presents an intriguing problem. Just what is
the origin of a hospital acquired case of gas gangrene-spore-laden dust
in an operating theatre, inadequately sterilised instruments or materials,
or the patient’s own flora? What is the source of an enterotoxin-producing
strain of C. perfringens in an outbreak of food poisoning? Similar questions
might be asked of botulism and tetanus. Means are available for answering
a few of these questions.
Historically, typing of only pathogenic bacteria has been considered and
this Chapter will be restricted to the pathogenic species of Clostridium
associated with gas gangrene, botulism, tetanus and food poisoning. Unfortunately, little work has been done on bacteriocin or bacteriophage typing
of clostridia and perhaps one of the major objectives of this contribution is
to review much of our knowledge on clostridial bacteriocins and bacteriophages with a view to suggesting potential typing schemes for various
species. An appreciation of some of the difficulties which might impede the
development of typing schemes should also be considered. A bacteriocin
typing scheme for C. perfringens developed in our laboratory is presented
as one possible model for typing the clostridia.
11. APPROACHES T O BACTERIOCIN TYPING
There are two approaches to bacteriocin typing. The first involves
examining the ability of isolates to produce bacteriocins active against a
standard set of indicator bacteria. T h e host range of any bacteriocin produced by the test strains then defines the typing pattern. One method of
performing this test is to inoculate a plate of an appropriate medium with
a single wide diametrical streak of the test organism. After growth (18 or
more hours) the bacteria are scraped off the plate and the plate exposed to
chloroform vapours. Subsequently the plate is aired to remove the chloroform before the standard indicator bacteria are streaked across the plate at
right angles to the original streak. The plates are incubated to allow growth
of the indicator bacteria. If bacteriocin has been produced by the test
strain, the growth of one or more of the indicator strains should be inhibited where the streakings intersect.
The second approach tests the susceptibility of unknowns to a standard
set of bacteriocins. This approach is less time consuming than the former
since only one incubation period is required. The test organism is simply
inoculated confluently over the surface of an agar plate as is done for anti-
D. E. MAHONY
same species, under appropriate conditions, are capable of causing destructive and sometimes fatal disease such as botulism, gas gangrene, clostridial
cellulitis, tetanus and the non-fatal but frequently encountered Clostridium
perfringens food poisoning. Because such organisms are ubiquitous, the possible typing of these bacteria presents an intriguing problem. Just what is
the origin of a hospital acquired case of gas gangrene-spore-laden dust
in an operating theatre, inadequately sterilised instruments or materials,
or the patient’s own flora? What is the source of an enterotoxin-producing
strain of C. perfringens in an outbreak of food poisoning? Similar questions
might be asked of botulism and tetanus. Means are available for answering
a few of these questions.
Historically, typing of only pathogenic bacteria has been considered and
this Chapter will be restricted to the pathogenic species of Clostridium
associated with gas gangrene, botulism, tetanus and food poisoning. Unfortunately, little work has been done on bacteriocin or bacteriophage typing
of clostridia and perhaps one of the major objectives of this contribution is
to review much of our knowledge on clostridial bacteriocins and bacteriophages with a view to suggesting potential typing schemes for various
species. An appreciation of some of the difficulties which might impede the
development of typing schemes should also be considered. A bacteriocin
typing scheme for C. perfringens developed in our laboratory is presented
as one possible model for typing the clostridia.
11. APPROACHES T O BACTERIOCIN TYPING
There are two approaches to bacteriocin typing. The first involves
examining the ability of isolates to produce bacteriocins active against a
standard set of indicator bacteria. T h e host range of any bacteriocin produced by the test strains then defines the typing pattern. One method of
performing this test is to inoculate a plate of an appropriate medium with
a single wide diametrical streak of the test organism. After growth (18 or
more hours) the bacteria are scraped off the plate and the plate exposed to
chloroform vapours. Subsequently the plate is aired to remove the chloroform before the standard indicator bacteria are streaked across the plate at
right angles to the original streak. The plates are incubated to allow growth
of the indicator bacteria. If bacteriocin has been produced by the test
strain, the growth of one or more of the indicator strains should be inhibited where the streakings intersect.
The second approach tests the susceptibility of unknowns to a standard
set of bacteriocins. This approach is less time consuming than the former
since only one incubation period is required. The test organism is simply
inoculated confluently over the surface of an agar plate as is done for anti-