CHOICE OF THE OPTIMAL METHOD FOR THE ISOLATION OF SALMONELLA FROM MEAT-AND-BONE-POWDER DESIGNED FOR INDUSTRIAL FEED MIXTURES

The purpose of this paper was (1) comparison of four multi-step method s used for Sabnonella isolation from meat- and bone powder; (2) elabor ation of a new sensitive method of Salmonella isolation from this prod uct; (3) evaluation of a new solid selective medium (BxLH) described b y the authors for Salmonella isolation in comparison to brilliant gree n agar (BGE) according to Edel and Kampelmacher. The study was carried out on 173 meat- and bone powder samples naturally contaminated with Salmonella oranienburg. The samples were examined for the Salmonella p resence by means of four compared methods (Methods 1 to 4). The new me thod of isolation proposed by the authors (Method 3) proved to be the most effective among all compared for Salmonella recovery. It seems th at the superiority of Method 3 in comparison to the other applied was a result of, (1) homogenization of the investigated samples in distill ed water before preincubation followed by maintenance at room temperat ure for 2-4 h; (2) the use of a new selective BxLH agar; (3) the use o f multiple plating after selective enrichment. The BxLH medium was sho wn to be more suitable for Salmonella isolation than BGE agar because of more efficient inhibition of other bacterial growth with simultaneo usly abundant growth of the Salmonella organisms. The additional advan tage offered by BxLH agar was the fact that lactose-positive salmonell as grow as typical representatives of this genus. This enables their i dentification, in contrast to the situation when lactose containing me dia are used, where the colonies of such salmonellas are similar to th e colonies of, for example, Escherichia coli.