Effect of temperature and agitation on enrichment of Escherichia coli O157:H7 in ground beef using modified EC broth with novobiocin.

The effects of temperature and agitation on the enrichment of Escherichia coli O157:H7 in meat using modified EC broth with novobiocin (mEC + n) were studied. Enrichment at 37 degrees C was compared to 42 degrees C, both with and without shaking. Incubation at 42 degrees C without shaking effectively suppressed ground beef microflora while allowing good growth of E. coli O157:H7 cells. Cells inoculated into ground meats (beef, pork, turkey) were readily detected by enrichment for 24 h in mEC + n at 42 degrees C without shaking, followed by screening the enrichment cultures using a rapid and inexpensive commercially available enzyme immunoassay system, the E. coli O157 Rapitest.