WASHINGTON – Food-safety scientists are becoming more concerned with lesser-known, emerging species ofEscherichia coliO157:H7, according to Pina Fratamico, US Department of Agriculture microbiologist and research leader.

In recent years, six of these emergingE. colispecies, also called "serogroups," have come to be known among food-safety specialists as "the Big Six," namelyE. coli O26, O45, O103, O111, O121 and O145. As a result, Fratamico and her team mates are attempting to learn more about the "who's who" among these related pathogens so the microbes can be identified and detected quickly and reliably. They are accomplishing this by uncovering clues in the microbes' genetic makeup.

Fratamico and her Agricultural Research Service (ARS), university and industry collaborators have developed gene-based PCR (polymerase chain reaction) assays for each targeted pathogen. With a little more work, the assays may eventually be introduced as user-friendly test kits to use by regulatory agencies and others. Food processors 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.

Researchers hope test result analyses will help determine whether certain strains of “the Big Six”E. coli species cause more illness thanE. coliO157:H7 does — and if they do, determine the reason.