The Centers for Disease Control and Prevention (CDC) has uncovered a new strain of E. coli that has been responsible for multiple outbreaks of foodborne illness over recent years, including those related to romaine lettuce and other leafy greens.
The REPEXH02 strain is believed to have first come to light at the end of 2015, with the agency noting that it was responsible for dozens of hospitalizations and many cases of hemolytic uremic syndrome (HUS), a serious issue that can often impede blood clotting in infected people and cause kidney failure.
A study by CDC researchers utilized whole genome sequencing to examine the DNA of a strain and track the bacteria that cause foodborne illness, which allowed them to determine whether outbreaks were caused by the same strain, and the link involved with others. The new strain consists of two clades with different geographic distributions, one of which has notable genomic features.
E. coli O157:H7 is estimated to cause 63,000 domestically acquired foodborne illnesses and 20 deaths in the United States each year, according to the CDC. The agency found that 58% of recent E. coli-related illnesses were attributed to vegetable row crops, with the majority coming from leafy greens. In 2019, a large outbreak related to romaine lettuce from California’s Salinas Valley caused 167 cases and hospitalized 85 people from 27 states. In 2020, 40 infections occurred in 19 states, 20 people were hospitalized and four developed HUS. No further outbreaks from the strain have been associated with the strain.
The newly identified strain has a toxin type associated with more severe disease in those infected, according to the CDC. Still, additional study is needed to understand factors that contribute to the bacteria’s emergence and persistence in specific environments, the authors wrote.