Sensitivity of Escherichia coli to Atabrine Conferred by R Factor and Its Potential Clinical Significance

摘要

A comparative study of the inhibitory effect of Atabrine on R? and R+ strains of Escherichia coli showed that R+ cells were killed when grown in the presence of Atabrine, whereas R? cells were not. It would appear, therefore, that R factor confers sensitivity to Atabrine on the host cells. The “curing” of R factor from R+ cells by the ultraviolet light-acridine orange method rendered the “cured” cells more resistant than even the parent R? cells. The “cured” cells reinfected by R factor were more sensitive than the “cured” cells but less sensitive than the original R+ cells. After growth once in Atabrine, and even after subcultures in drug-free medium, the growth of R+ cells in the presence of Atabrine was more rapid than that of the R? cells. R? cells made resistant by growing them repeatedly in streptomycin, chloramphenicol, tetracycline, and sulfathiazole in succession also showed a higher degree of sensitivity to Atabrine than the original R? cells. When mixtures of R? and R+ cells were grown in 120 μg/ml of Atabrine, R+ cells were killed and the culture consisted predominantly of R? cells. A mixture of R? and R+ cells (1:10,000) inoculated into the Atabrine-containing medium and treated 24 hr later with chloramphenicol was completely killed.