The majority of the bacteria in this group are micrococci, and on the other hand most of the pathogenic micrococci belong to this group. The group is characterized by the fact that the microbes induce acute inflammations frequently resulting in suppurations. Hence the term Pyogenic, that is, producers of pus.

The toxine of the pyogenic microbes is, according to Buchner, a proteid substance which is present in the bacteria themselves. This substance does not lose its virulence even when heated for hours to 120° C. The toxine produces suppuration apart from the microbes.