Development of listeria monocytogenes in monoxenic and polyxenic beef minces.

The objective of this study was to determine the multiplication possibilities of Listeria monocytogenes in beef minces with a defined microflora (gnotoxenic). Selective counts were made for each species and each bacterial association for a period of 17 days after inoculation of the axenic meat. The concentration of L. monocytogenes did not increase, but remained constant in monoxenic meats. Associated with Lactobacillus plantarum, the number of Listeria tended to decrease. Conversely, in association with P. fluorescens, L. monocytogenes definitely multiplied, especially in polyxenic meats, the microflora of which is similar to that of conventional meats. Consequently, it seems that meat might constitute a source of L. monocytogenes infection.