DEVELOPMENT OF RICKETTSIAL DRUG RESISTANCE TO ANTIBIOTICS IN MICE

Abstract

The auther examined whether R. tsutsugamushi (R.) might develop a drug resistance to Chlortetracycline (CTC) or not, using mouse as an experimental animal. R. was inoculated intraperitoneally to each mouse in groups which received various dosis of CTC by mouth. Then from those mice R. were isolated for the next generations. The following results were obtained.
1. In third generations, R. developed no drug resistance to CTS in each groups of receiving 0.1mg for 3-4 days, 0.05mg for 3-4 days and of 0.05mg for 7 days.
2. But in fifth generations, received 0.025mg for 7 days in each generation, it seemed to be developing some resistance to CTC.
3. In 7th generations, in the group which received 0.05mg for 7 days, R. developed more resistance than in the group receiving 0.05mg for 4 days.
4. The R. strain, which isolated from mice of 7th generations, received CTC 0.05mg for 7 days in each generation, revealed cross resistance to Tetracycline, but not to Chloramphenicol & Leukomycin.
5. The CTC resistant strain was passed mice receiving no antibiotics through 12 generations, but the resistance was not weakened or not disappeared.
6. In above mentioned experiments no change in rickettsia's virulence was noticed.
7. Also in the experimental rickettsiosis in mice, the author has proved that the long-term administration of small amount of antibiotic was efficacious.