MSNBC’s JoNel Aleccia reported this morning “Testing for new E. coli strains in beef finally to begin.”

The move implements long-delayed federal regulations aimed at a group of E. coli bacteria collectively known as “the Big Six,” bugs capable of causing severe infection and death.

Under the new rules, the six additional strains of E. coli will be classified as adulterants on par with the better-known E. coli O157:H7, which is often linked to serious illnesses tied to hamburger. The new strains include E. coli O26, O111, O103, O121, O45 and O145.

Beginning Monday, it will be illegal to sell raw beef trimmings and non-intact beef products, such as tenderized steaks, if they’re contaminated with any of the six new strains of E. coli, according to documents from the Food Safety and Inspection Service of the U.S. Department of Agriculture.

The agency indicated it plans in the future to expand routine testing for those strains to additional raw beef products, including ground beef.

Like E. coli O157:H7, the six new strains are capable of producing bloody diarrheal illness that can lead to kidney failure and death. In 2010, for the first time, the non-O157 strains of what are known as Shiga toxin-producing E. coli, or STECs, were responsible for more infections in the U.S. than E. coli O157:H7, according to federal health officials.

The non-O157 STECs caused 451 confirmed infections that year, including 69 people who were hospitalized and one death. E. coli O157:H7 caused 442 infections, 184 hospitalizations and two deaths, according to the Centers for Disease Control and Prevention. Many illnesses are never reported, however, and the agency estimates that non-O157 E. coli strains cause an estimated 113,000 illnesses and 300 hospitalizations a year.

The new testing requirement is a victory for Bill Marler, a Seattle food safety lawyer who petitioned FSIS to have the “Big Six” strains declared adulterants and then threatened to sue the USDA when the agency didn’t respond promptly.

He pointed to the 1994 classification of E. coli O157:H7 as an adulterant as a turning point for food safety in U.S. and said the new rules would have a similar effect.

“(It) dramatically changed the landscape of how safe our meat supply is for the better,” he said. “This is another step in getting this done correctly.”

According to the Center for Infectious Disease Research & Policy (CIDRAP), these six STEC strains account for 80 percent of non-O157 E. coli illnesses infections. The Centers for Disease Control and Prevention estimates non-O157 E. coli strains cause 112,000 illnesses annually, with about 36,700 of those attributed to beef.