[Isolation of a specific agglutinating serum K 99].

A specific agglutinative and absorbed K 99 antiserum was produced and also the presence of the antigen K 99 was proved in strains E. coli, isolated from calves. It was proved that out of 272 strains E. coli 46/16.9% are positive for antigen K 99. It was also found out that 95.3% of the enteropathogenic and 2.1% of the non-enteropathogenic E. coli contain the antigen K 99. The antigen K 99 is produced at a temperature of 37 degrees C and not at 18 degrees C and is unstable as regards temperature.