Abstract
In the first report it was pointed out that the Zinsser's agar-slant tissue culture by using 10 day chick embryo tissue might be available for screening drugs effective on the inhibition of growth of Coxiella burnetii (C. b.) on the bases of fundamental investigations. In this report a minimal inhibition dose of each of antibiotics (chloramphenicol (CM), magnamycin (MM), achromycin (TC), streptomycin (SM) and penicillin (Pc)) and chemicals (diazin and para-aminobenzoic acid (PABA)) was estimated by adding various amounts of those drugs into the Zinsser's agar-slant tissue culture. The results were obtained as follows.
1. The growth of C. b. was inhibited to 100 per cent by adding CM in 5γ/ml to the culture medium. But C. b. proved to grow in the next passage on the culture medium without antibiotics. Accordingly it seems very likely that CM may not have coxiellicidal property but coxiellostatic.
2. 1γ/ml of TC gave a remarkable effect on both inhibition and delay of the growth of C. b. and its dose ranging 10-5γ/ml inhibited the growth of C. b. approximately to 100 per cent.
3. 10γ/ml of MM delayed and inhibited markedly the growth of C. b., and almost C. b. disappeared in the infected tissue by adding 15γ/ml of it.
4. The growth of C. b. was, to some extent, inhibited and delayed by adding 30-100γ/ml of SM to the culture. Such a phenomenon became marked by adding 200-400γ/ml of SM while 1000γ/ml of Pc allowed C. b. to grow well like the control without antibiotic.
The effectiveness of antibiotics and chemicals mentioned above may be compared as follows: TC>CM>MM>SM>Pc.
5. No evidence was obtained for C. b. to become adapted or resistant to CM after 7 passages on Zinsser's medium containing 5γ/ml of CM.
6. The growth of C. b. could not be inhibited on the culture added diazin to 2mg/ml. Such a test may be available for classification of C. b. from psittacosis virus group. 2mg/ml of PABA proved to be sightly effective on the inhibition of growth of C. b.. It may be useful for separating C. b. from rickettsia.
7. The effectiveness of TC and MM had no remarked tendency to fall in both medium groups preserved for 1 day at 37°C and for 1 day at 37°C and then 14 days at room temperature.
8. 20γ/ml of TC added to the Zinsser's medium allowed chick embryo cells which were cultivated for 8 days at 37°C to grow well like normal chick embryo cells in the stational culture medium in the next passage.
