Abstract
The causative agent of Q fever, Coxiella burnetii, was reported to be cultivated by Maitland's method (Burnet and Cox), in yolk sac of developing chick embryo (Cox), and by Zinsser's agar-slant tissue culture (Takemori and Kitaoka). Herewith an attempt was made to determine whether or not the Zinsser's agar-slant tissue culture was avialable for screening any antibiotic and chemical effect upon the inhibition of growth of Coxiella burnetii. Prior to using this culture method for this purpose, it should be investigated more in detail concerning the tissue to be cultivated, daily occurence of the tissue culture and the resistance of the agent in the culture. The results were obtained as follows.
1. Coxiella burnetii. can be cultivated by the Zinsser's agar-slant tissue culture by using tissues of human-, chick-, guinea-pig-, rat- and mouse- embryos, testicle, kidney and spleen of adult guinea-pigs, rat rhodamine sarcoma and mouse furctose sarcoma. In general, the tissues of human-, guinea-pig- and chick embryos gave better growth of the agent than the other tissues mentioned above.
2. The agent could not been recognized under microscope in 1-2 days, but appeared in 3 days and showed a maximum growth in 4-5 days after its cultivation by using chick embryo tissue.
Such a maximum growth was observed for 20 days though the agent decreased a little in number.
3. Aa for ID50 of infected chick embryo tissue, it may be computed by the passage method with each ten fold dilution of each daily infected tissue from 10-1 to 10-8, that 104.5, 105.5 and 105.2 of ID50 were calculated immediately, 1 and 2 days respectively after the cultivation. During this period the microscopical findings were proven to be Coxiella negative. But ID50 of infected tissue was estimated 107.5 on the 8th day after its cultivation, when numberless coxiellae were found under microscope.
4. Coxiella was able to be cultivated by the passage after it was preserved at 37°C. for 12 months.
5. Coxiella grew in Zinsser's agar-slant tissue culture by using lace albumine hydrolysate instead of horse serum, when the former seemed to cause a little less growth than the latter.
