Recent work has shown that strains classified as M. mycoides subsp. mycoides may be separated into 2 types according to their growth rate and their behaviour in certain biochemical tests. The large colony (LC) types, most of which are from goats, are pathogenic for sheep and goats but apparently not for cattle. The small colony (SC) types include the classical contagious bovine
pleuropneumonia (CBPP) strains from cattle and four strains from goats. These SC types are potentially pathogenic for cattle, sheep and goats. Strains of M. mycoides subsp. mycoides from CBPP differ in their virulence in cattle. The degree of virulence is correlated with the quantity of
galactan produced in cultures of the organism, suggesting an important role for
galactan in pathogenicity. This is consistent with the production by
galactan of physiological effects in calves and in the enhancement of
infection in cattle given
galactan at the same time as cultures of the organism. Contagious caprine
pleuropneumonia (CCPP) can be produced experimentally in goats using cultures of M. mycoides subsp. capri. Whether the
glucan produced in such cultures is
a factor in pathogenicity of this organism has not been determined.
Hydrogen peroxide demonstrated in tracheal organ cultures of M. mycoides subsp. capri may contribute to its pathogenicity.