Enteric Bacteria

Biochemical confirmation of salmonellae by conventional tube methods usually requires 2 to 3 days of incubation time preceded by preparation of tubed media and transfer of cultures. The principles of heavy inocula and increased substrate concentrations have been used by Sanders et al. (1) to speed up reaction times and thus reduce the time necessary in the laboratory for analysis. To characterize pure cultures, they used paper discs with carbohydrates that were seeded in pour plates of modified phenol red agar base containing sodium thiosulfate. We also have studied the disc method. Our procedure is as follows. Isolated colonies on selective agars were picked for overnight growth at 37 C in veal infusion broth. Therefore, the heavy growth necessary for the seeding of plates was obtained. These broth-booster cultures were transferred to molten agar, and these overlayed