Detection and Identification of Salmonella from Dry Milk: Report of a Collaborative Study

Abstract

Abstract A method for the detection and identification of Salmonella from dry milk was subjected to collaborative study. A 100 g sample is reconstituted in 1 L distilled water with 2 ml 1% aqueous brilliant green dye, incubated, subcultured in selenite cystine broth and tetrathionate broth, incubated, and streaked on selective plates of brilliant green agar, Salmonella-Shigella agar, and bismuth sulfite agar. After incubation, suspicious colonies can be further identified by biochemical and serological tests. Samples of nonfat dry milk and dry whole milk, some inoculated with Salmonella binza, Salmonella tvorthington, and Citrobacter, were examined by 30 collaborators. Results from 23 of 28 collaborators were in agreement; the method will detect and identify Salmonella from positive nonfat dry milk and dry whole milk. The method is recommended for adoption as official first action.