MEDIUM FOR THE QUANTITATIVE RECOVERY OF MEMBERS OF THE GENERA PASTEURELLA AND BRUCELLA.

A modification of peptic digest-starch (PDS) medium for the quantitative enumeration of Pasteurella tularensis is described. This modification (PDM), in which the concentration of L-cysteine was decreased and in which Brilliant Green was substituted for the penicillin added to the original medium, was evaluated and was found satisfactory for the recovery of P. tularensis, P. pestis, and members of the genus Brucella, from freshly harvested and stored cultures as well as aerosolized organisms produced therefrom. With weakly virulent strains of P. tularensis, such as the Jap 4 and LV strains, it was found that PDM was not adequate.