The U.S. Food and Drug Administration recently found Listeria monocytogenes in an onion processing facility in Washington state where some wholesale vegetable products, recalled in April are linked to illnesses. According to the U.S. Centers for Disease Control and Prevention, consumption of the recalled vegetable products was linked to nine cases of listeriosis reported from four states between September 2013 and May of this year. CDC officially declared that outbreak over on July 15.
The Oregon Potato Co., doing business as Freeze Pack, was told in a July 15 warning letter from FDA’s Seattle District Office that, following a March inspection of its processing plant in Pasco, Washington, a number of environmental swabs taken there tested positive for the pathogen.
FDA’s laboratory analysis of samples collected March 8 and 9 confirmed that 19 out 106 environmental swabs tested positive for Listeria monocytogenes.
The warning letter noted that seven positive environmental swabs were collected from direct food contact surfaces in the plant’s processing and packaging rooms during the production of individually quick frozen (IQF) diced onions.
The 19 environmental samples were also analyzed using whole genome sequencing (WGS), which FDA noted can establish direct links between clinical isolates from sick people and food or environmental sources. The analysis found links between the isolates from the production plant and sick people, the agency stated.
“The WGS phylogenetic analysis establishes that there are at least two different strains of L. monocytogenes present in the facility, with one strain containing 17 isolates and the second strain containing two isolates,” FDA stated.
“Specifically, the WGS analysis of the strain with 17 isolates showed that the isolates are identical to each other. WGS analysis of the strain with two isolates showed that the isolates are identical to eight cases of human illness dating back to 2013, and to six isolates from finished products. These finished products included onions, with two isolates in 2014, and green beans with three isolates in 2015, tested by a third party laboratory, and a single isolate from white sweet corn collected and tested by the state of Ohio in 2016. Additional investigation established that at least six individuals were hospitalized as a result of related L. monocytogenes associated illness,” according to the warning letter.
The Oregon Potato Co. recall led to numerous secondary recalls of frozen vegetables by other companies and brands, including Reser’s Fine Foods, Pictsweet and Schnucks. It is associated with a large recall of frozen vegetables initiated by CRF Frozen Foods Inc.