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 above the sterile agar plate, the inoculation needle will be streaked across the plate in controlled directions. Microbial aerosols can be created from the hitting of the inoculation tip to the sides of the agar plate. The inoculation needle is then withdrawn from the inoculated agar plate culture and flamed. An inoculation needle is an essential tool in inoculating a stab culture. A sterile stab culture cap is removed and the open end is flamed. The needle tip and its length is then pushed into the stab media and stopped once the needle tip reaches 0.5 inches away from the