Lesser-known Escherichia coli types targeted in food safety research

Almost everyone knows about Escherichia coli O157:H7, the culprit behind many headline-making outbreaks of foodborne illness in the United States. But the lesser-known relatives of this pathogenic microbe are increasingly of concern to food safety scientists.

That's according to U.S. Department of Agriculture (USDA) microbiologist and research leader Pina M. Fratamico. Researchers such as Fratamico, along with food safety regulators, public health officials and food producers in the United States and abroad, want to know more about these less-studied pathogens.

In the past few years, a half-dozen of these emerging E. coli species, also called "serogroups," have come to be known among food safety specialists as "the Big Six," namely E. coli O26, O45, O103, O111, O121, and O145.

Fratamico and her colleagues are sorting out "who's who" among these related pathogens so that the microbes can be identified and detected quickly and reliably. The researchers are doing that by uncovering telltale clues in the microbes' genetic makeup.

Building upon this work, Fratamico and her Agricultural Research Service (ARS), university, and industry collaborators have developed gene-based PCR (polymerase chain reaction) assays for each of the Big Six. With further work, the assays might be presented as user-friendly test kits for use by regulatory agencies and others. Foodmakers, for example, might be able to use such kits for in-house quality control, while public health agencies might rely on them when processing specimens from patients hospitalized with foodborne illness.

Analyses of test results might help researchers determine whether certain strains of Big Six E. coli species cause more illness than E. coli O157:H7 does, and if so, why.