A CDC- and FDA-led investigation found the outbreak, which sickened 104 people in 14 states, was likely caused by slivered onions supplied by Taylor Farms.
Analysis of clinical isolates of E coli ST131 identified 18 different carbapenemase genes, which could limit treatment options.
The carrots were sold under different brands at a number of popular retailers in the US and Canada, including Trader Joe's, Wegman's, and Safeway.
A total of 104 people have been sickened, with 34 hospitalizations, 4 cases of hemolytic uremic syndrome, and 1 death.
The researchers found foodborne pathogens that had formed colonies of pathogens in a sticky biofilm in three common types of plastic in raw and treated wastewater.
The outbreak has now sickened 90 people in 13 states, with 27 people hospitalized.
The number of people sickened in the multistate E coli O157:H7 outbreak has risen from 49 to 75, with 22 hospitalized.
Federal investigators are looking at ground beef and slivered onions as potential sources of the outbreak.
Climate change will have increasing effects on public health and food security over time, the authors say.
Nearly 12% of E coli isolates from dogs and cats in German veterinary practices were resistant to third-generation cephalosporins.
