BCG vaccine bacilli that seemed less virulent, and changed the course of their research to see if repeated subculturing would produce a strain that was attenuated enough to be considered for use as a vaccine. The BCG strain was isolated after subculturing 239 times during 13 years from virulent strain on glycerine potato medium. The research continued throughout World War I until 1919, when the now avirulent bacilli were unable to cause tuberculosis disease in research animals. Calmette and Guerin transferred to the Paris Pasteur Institute in 1919. The BCG vaccine was first used in humans in 1921. Public acceptance was slow,
Inoculation needle culture. Too much heat will kill off the inoculum during the direct contact of a flamed inoculation needle. The inoculation needle is withdrawn from the agar culture after obtaining a small colony and the agar plate lid is then replaced. Inoculation of the microorganisms will be done directly after the transfer from culture to inoculation needle. The inoculum is commonly inoculated to broth cultures, slant cultures, plate cultures, and stab cultures. An inoculation needle is used in inoculating a sterile broth culture. Flaming the open end of the broth will keep the it sterile. The broth will be moved up