The establishment of K99, a thermolabile, transmissible escherichia coli K antigen, previously called "Kco", possessed by calf and lamb enteropathogenic strains.

The transmissible antigen in enteropathogenic E. coli strains from calf and lamb, previously called Kco, is established as the E. coli K99 antigen. It is probably of protein nature since it is destroyed by heating. It is pointed out that other antigens present, growth medium and unknown factors are of great importance for the demonstration of this antigen.