Evolution and taxonomy in the genus Brucella: steroid hormone induction of filterable forms with altered characteristics after reversion.

Several strains of Brucella abortus, Brucella suis, and Brucella melitensis were exposed to physiologic concentrations of testosterone, progesterone, and diethylstilbestrol by incorporating them into the growth medium. The hormones induced Brucella to form cell wall-defective organisms, including filterable forms. The filterable forms from 1 strain of B melitensis had altered characteristics when it reverted to growth as an intact cell. This is the 1st reported instance of induction of filterable forms of Brucella by progesterone, testosterone, and diethylstilbestrol.