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 to the needle so that the needle tip is submerged while maintaining the needle's original position. Careful swirling of the needle can help the inoculation of the microorganism from the needle to the sterile broth. The inoculated broth culture is then removed from the needle. Aseptic technique is applied to the open end of the broth culture to prevent contaminants, and the needle is flamed for sterilization. An inoculation needle is used to inoculate a slant culture in a fish tail inoculation technique. After the microorganisms transfer from the original microbial culture to the inoculation needle the sterile slant culture