24
D. E. MAHONY
Hobbs’ 13 antisera. Of 30 strains obtained from food poisoning cases in
England, Europe and Asia, 20 agglutinated with the antisera. These
strains resembled those described by Hob‘bs. None of 25 American strains
of C. perfringens un-associated with food poisoning agglutinated with
Hobbs’ antisera and none of these strains produced heat resistant spores.
Of 28 American strains associated with food poisoning, only 12 were
agglutinated with Hobbs’ sera, many were without heat-resistant spores,
but all were haemolytic. Subsequently, Hobbs et al. (1973) also reported
heat-sensitive strains implicated in food poisoning and two sets of antisera
-Hobbs type 1-24 for heat-resisting strains and types i-xviii for heatsensitive strains have been developed.
Hughes et al. (1976) have revised the latter typing scheme and have
assigned arabic numerals to Hobbs’ Roman numeral scheme in addition
to employing a total of 57 different antisera for typing C. perfringens.
Sixty-five per cent of isolates from 153 food-poisoning outbreaks were
typable as well as 59% of the isolates from 32 cases of gas gangrene and
other clinical infections. In 55% of the food-poisoning outbreaks, the
causative serotypes were established. From the same laboratory, Stringer
et al. (1976) have proposed an international serotyping system for C.
perfringens type A which would utilise specific antisera from England,
Japan and the United States.
Dowel1 and Hawkins (1974) described the slide agglutination test used
at the Centre for Disease Control, Atlanta, Georgia, U.S.A. Essentially a
strain of C. perfringens to be typed is grown in a fluid “antigen” medium
for 18 h which is then centrifuged at 12,350 x g for 10 min. The sediment
is resuspended in 0.4% formolised 0.85% saline to prepare a turbid
suspension for slide agglutination. Drops of C. perfringens antisera (Hobbs
types 1-13) are placed on marked segments of a glass slide and a drop of
antigen is added to each segment and mixed with the antisera by tilting
the slide. After 30 s, agglutination intensity is recorded ranging from 1 +
to 4 + reactions. The Anaerobic Bacteriology Laboratory, Centre for
Disease Control, Atlanta, has 74 specific C. perfringens antisera in addition
to the 13 Hobbs’ antisera which are used in analysing strains of C. perfringens obtained in outbreaks of food poisoning.
Typing of C. perfringens by the fluorescent antibody (FA) technique
should be discussed. Klotz (1965) prepared antisera to 56 different strains
of C. perfringens including 13 Hobb’s strains. The antisera were labelled
with fluorescein isothiocyanate (FITC) and used to type 79 strains, 34 of
which gave strong reactions. Twenty-one strains agglutinated with the
Hobbs’ antisera; 18 were untypable and 27 gave equivocal results. In spite
of the inability to type 57% of the strains, the FA method closely matched
the slide agglutination test and was a more sensitive indicator of antigenic
D. E. MAHONY
Hobbs’ 13 antisera. Of 30 strains obtained from food poisoning cases in
England, Europe and Asia, 20 agglutinated with the antisera. These
strains resembled those described by Hob‘bs. None of 25 American strains
of C. perfringens un-associated with food poisoning agglutinated with
Hobbs’ antisera and none of these strains produced heat resistant spores.
Of 28 American strains associated with food poisoning, only 12 were
agglutinated with Hobbs’ sera, many were without heat-resistant spores,
but all were haemolytic. Subsequently, Hobbs et al. (1973) also reported
heat-sensitive strains implicated in food poisoning and two sets of antisera
-Hobbs type 1-24 for heat-resisting strains and types i-xviii for heatsensitive strains have been developed.
Hughes et al. (1976) have revised the latter typing scheme and have
assigned arabic numerals to Hobbs’ Roman numeral scheme in addition
to employing a total of 57 different antisera for typing C. perfringens.
Sixty-five per cent of isolates from 153 food-poisoning outbreaks were
typable as well as 59% of the isolates from 32 cases of gas gangrene and
other clinical infections. In 55% of the food-poisoning outbreaks, the
causative serotypes were established. From the same laboratory, Stringer
et al. (1976) have proposed an international serotyping system for C.
perfringens type A which would utilise specific antisera from England,
Japan and the United States.
Dowel1 and Hawkins (1974) described the slide agglutination test used
at the Centre for Disease Control, Atlanta, Georgia, U.S.A. Essentially a
strain of C. perfringens to be typed is grown in a fluid “antigen” medium
for 18 h which is then centrifuged at 12,350 x g for 10 min. The sediment
is resuspended in 0.4% formolised 0.85% saline to prepare a turbid
suspension for slide agglutination. Drops of C. perfringens antisera (Hobbs
types 1-13) are placed on marked segments of a glass slide and a drop of
antigen is added to each segment and mixed with the antisera by tilting
the slide. After 30 s, agglutination intensity is recorded ranging from 1 +
to 4 + reactions. The Anaerobic Bacteriology Laboratory, Centre for
Disease Control, Atlanta, has 74 specific C. perfringens antisera in addition
to the 13 Hobbs’ antisera which are used in analysing strains of C. perfringens obtained in outbreaks of food poisoning.
Typing of C. perfringens by the fluorescent antibody (FA) technique
should be discussed. Klotz (1965) prepared antisera to 56 different strains
of C. perfringens including 13 Hobb’s strains. The antisera were labelled
with fluorescein isothiocyanate (FITC) and used to type 79 strains, 34 of
which gave strong reactions. Twenty-one strains agglutinated with the
Hobbs’ antisera; 18 were untypable and 27 gave equivocal results. In spite
of the inability to type 57% of the strains, the FA method closely matched
the slide agglutination test and was a more sensitive indicator of antigenic