Abstract
A total of 112 strains of Francisella tularensis isolated from different countries and from different sources were tested for susceptibility to various antibiotics. All of them were uniformly not susceptible to penicillin, cephalosporin C and polypeptide antibiotics, but were all susceptible to aminoglycoside, chloramphenicol and tetracycline. As to macrolide antibiotics, however, they belonged to either highly sensitive or highly resistant group. The former group consisted of strains isolated from China, Italy, Japan, and the U.S.A., and the latter one of strains from the U.S.S.R. and East European countries. These results are quite consistent with those reported by Russian workers, who observed that the susceptibility of the organism to erythromycin differed according to the place from which the organism had been isolated.
The results mentioned above seem to show that the susceptibility of F. tularensis to macrolide antibiotics may be a genetic marker which is independent of the virulence and other biochemical properties of the organism and may offer a basis for understanding the origins of various strains of the organism.
