Methods for the isolation of Brucella abortus

Abstract

Abstract does not appear. First page follows. Owing to the greatly increased interest in Brucella abortus since it has been definitely established as a human pathogen and since its economic importance has been more widely recognized, the attempted isolation of the organism from suspected materials has become a routine practice in a large number of laboratories not previously interested in the Brucella group. The procedures given below, together with some experimental data, are based on several years’ work of this and other laboratories interested in bovine-abortion control. For the most part the methods are those in general use or modifications of such. These methods have uniformly given satisfactory results in research and also in routine diagnosis such as certified-milk inspection and control work in other dairy herds. Because of these results, which have been obtained from the inoculation of several thousand guinea pigs, it was thought that a detailed description of the technique might be of value, in whole or in part, to other workers. In addition to outlining the methods used, an attempt has been made to compare and evaluate the various procedures. Direct Culture Method Although the isolation of Brucella abortus by guinea-pig inoculation, especially from milk, has been the most widely accepted method for many years, from time to time the use of culture media for the direct isolation of the organism from suspected material has been advocated. The most recent work on this method is that of Huddleson, Hasley, and Torrey.(13) For the isolation of Br. abortus from milk, these workers use liver-infusion agar to which is added a saturated aqueous solution of gentian violet in the proportion of 1 part to 10,000 parts of culture medium. The medium is allowed to harden in petri dishes, and 0.1 cc of cream is spread over the surface of the plate. The dye inhibits the growth of most of the other bacteria in the milk, but allows Br. abortus to develop. The advantages of this method of isolation are numerous.