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 forms to ensure no contamination of the culture, the sterile mediums, and the surrounding environment. In inoculation the inoculation needle is first employed to transfer microbial life forms from a culture to the needle to be used in further inoculating procedures. Sources of inoculum include broth cultures, slant cultures, and plate cultures. An inoculation needle is used in the transfer of microorganisms from a broth culture by first employing a vortex mixer to ensure a uniform suspension of the microorganisms within the broth. Aseptic technique is then applied to the needle. Once the needle is flamed and sterilized the culture