In Vitro Susceptibility of a Strain of Rickettsia Recently Isolated from a Case of Japanese Spotted Fever to Chemotherapeutic Agents

Abstract

The in vitro susceptibilities to five chemotherapeutic agents against a rickettsial strain which was isolated from a case of Japanese spotted fever were determined by cell culture system. Minocycline was the most effective (MIC, 0.15 micrograms/ml) followed by Tetracycline and Demethylchlor tetracycline (0.31 micrograms/ml 0.16 micrograms/ml). Chloramphenicol was less effective (5 micrograms/ml) and Aminobenzyl-penicillin was not effective with the MIC of 10 micrograms/ml or less. Thus, the earlier administration of Minocycline is recommended to clinically suspicious cases of Japanese spotted fever as well as Tsutsugamushi disease.