An official website of the United States government.
This project will develop a medium containing hemin as the iron source for the selection of E. coli 0157:H7. The potential high selectivity of this medium without harsh chemicals could allow for greater recovery of injured organisms than currently used media. In addition, the iron restricted hemin supplemented media will be evaluated for the isolation for non-0157:H7 SLTEC.
Recently, the USDA has issued a final rule to mandate pathogen reduction and HACCP systems in meat animal slaughtering establishments. Much of the current concern about the safety of the fresh meat supply stems from outbreaks of hemorrhagic colitis caused by ingestion of under-cooked hamburger that contained the bacterium Escherichia coli 0157:H7. In some cases, the illness was fatal. While the majority of all E. coli organisms do not cause human illness, the pathogenesis of E. coli 0157:H7 is thought to be related to its ability to produce toxins called Shiga-like toxins.E. coli that produce the Shiga-like toxins are referred to as SLTEC. The major problems with screening foods for SLTEC have been the differentiation of these organisms from non-pathogenic E. coli and other food bacteria.Identification of E. coli 0157:H7 is performed by screening for organism that have the inability to use the sugar sorbitol. This media will select for only 0157:H7 and will not identify all SLTEC. An observation that all tested strains of E. coli 0157:H7 could use heme as a sole source of iron, identified a unique possibility for selective media formulation.