111. TYPING OF E. INSIDIOSA
55
E. Haemagglutination
the standard methods.
Haemagglutination activity of the strains studied was determined by
111. RESULTS OF T H E VARIOUS TYPING PROCEDURES
A. Typing by microprecipitation
Using acetic acid extracts, the characteristic precipitation lines appeared
within 2 h and were fully developed after 6-8 h. At 24 h they were still
characteristic but became more diffuse and more difficult to interpret
later.
Of 80 strains of E. insidiosa studied, 30 reacted positively with serogroup
A specific antiserum, 42 with serogroup B specific antiserum and eight
failed to react. The latter have been designated the N group.
B. Typing by bacteriophage
Only two strains of the serogroup B type and none of serogroup N were
lysed by the serogroup A Erysipelothrix phage. All strains of serogroup A
were lysed.
C. Typing by haemadsorption and haemagglutination
The colonies of some strains of E. insidiosa adsorb poultry erythrocytes
intensely on to their surface. The erythrocytes form a compact layer
which cannot easily be disintegrated by washing. The layer of erythrocytes
ends sharply at the edge of the colony and does not spread on to the agar
surface. It is more compact at the edges and sometimes on the top of the
colonies while on the sloping surfaces the layer is more or less broken.
This .type of adsorption is designated as + + + + or + + + . The colonies
of other strains adsorb only solitary erythrocytes most often on their
periphery. Such adsorption is indicated by + or & . Some strains show no
ability to adsorb and this is recorded as a negative (-) reaction. Colonies
produced after 48, 72 or 96 h incubation were suitable for demonstrating
haemadsorption with hen erythrocytes but 24 h colonies were too young,
washing readily from the surface of the agar. Erythrocytes of sheep,
guinea pig and rabbit were not adsorbed and were unsuitable for tests with
E. insidiosa. Adsorption persisted at 4-6°C for at least 96 h.
The pretreatment of E . insidiosa colonies with specific anti-Erysipelothrix serum completely blocked haemadsorption. Normal pig serum had no
such inhibitory action.
Strains which were typed by microprecipitation as serogroup A showed
55
E. Haemagglutination
the standard methods.
Haemagglutination activity of the strains studied was determined by
111. RESULTS OF T H E VARIOUS TYPING PROCEDURES
A. Typing by microprecipitation
Using acetic acid extracts, the characteristic precipitation lines appeared
within 2 h and were fully developed after 6-8 h. At 24 h they were still
characteristic but became more diffuse and more difficult to interpret
later.
Of 80 strains of E. insidiosa studied, 30 reacted positively with serogroup
A specific antiserum, 42 with serogroup B specific antiserum and eight
failed to react. The latter have been designated the N group.
B. Typing by bacteriophage
Only two strains of the serogroup B type and none of serogroup N were
lysed by the serogroup A Erysipelothrix phage. All strains of serogroup A
were lysed.
C. Typing by haemadsorption and haemagglutination
The colonies of some strains of E. insidiosa adsorb poultry erythrocytes
intensely on to their surface. The erythrocytes form a compact layer
which cannot easily be disintegrated by washing. The layer of erythrocytes
ends sharply at the edge of the colony and does not spread on to the agar
surface. It is more compact at the edges and sometimes on the top of the
colonies while on the sloping surfaces the layer is more or less broken.
This .type of adsorption is designated as + + + + or + + + . The colonies
of other strains adsorb only solitary erythrocytes most often on their
periphery. Such adsorption is indicated by + or & . Some strains show no
ability to adsorb and this is recorded as a negative (-) reaction. Colonies
produced after 48, 72 or 96 h incubation were suitable for demonstrating
haemadsorption with hen erythrocytes but 24 h colonies were too young,
washing readily from the surface of the agar. Erythrocytes of sheep,
guinea pig and rabbit were not adsorbed and were unsuitable for tests with
E. insidiosa. Adsorption persisted at 4-6°C for at least 96 h.
The pretreatment of E . insidiosa colonies with specific anti-Erysipelothrix serum completely blocked haemadsorption. Normal pig serum had no
such inhibitory action.
Strains which were typed by microprecipitation as serogroup A showed