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 needle-oriented culture methods. The application of inoculation needles focuses on the inoculation and isolation of very defined regions of the cultures and the requirements of least disturbance between two closely crowded microbial colonies. It can also be used in harpooning under a low magnification microscope. Streaking on streak plates, fish tail inoculation of slant cultures and the inoculation of stab cultures can be done with the inoculation needle. Stab cultures specifically require the inoculation needle and is used to study cell motility, microbial oxygen requirements using Thioglycolate cultures, and the gelatin liquefaction of bacteria. The inoculation needle is sterilized using