Shiga Toxin–Producing Escherichia coli (STEC) O157:H7 and Romaine Lettuce: Source Labeling, Prevention, and Business

Abstract

From May to November most romaine lettuce shipments in the United States come from California’s Central Coast region, whereas from December to April most come from the Yuma, Arizona, region. During 2017–2018, the 3 outbreaks of Shiga toxin–producing Escherichia coli (STEC) O157:H7 in US romaine lettuce all occurred at the tail end of a region’s production season. During the fall 2018 outbreak, the US Food and Drug Administration (FDA) recommended that suppliers begin labeling romaine packaging so that consumers can identify the product’s harvest region. We used publicly available data to show that labels may not avert many illnesses in future outbreaks but may reduce suppliers’ financial losses and reduce food loss. Market data available during both 2018 outbreak investigations showed that there was no romaine production from one of the 2 regions when the first illness onset occurred. That is, at the beginning of an outbreak investigation, market data may allow the FDA to quickly rule out an entire production region as a source of contamination.

Seasonality, shelf life and storage atmosphere are main drivers of the microbiome and E. coli O157:H7 colonization of post-harvest lettuce cultivated in a major production area in California

“…Importantly, our observed seasonality of EcO157 behavior and microbiome composition in MAP lettuce provides the first biological basis for the higher incidence of outbreaks of STEC infection linked to lettuce harvested in the late growth season in coastal California (September–October) [ 33 , 34 ]. Our results are in agreement with ‘fall season’, ‘processing and storage’, and ‘end-of-shelf life’ presenting the highest risks of EcO157 infection, as identified by quantitative microbial risk assessment based on numbers of Enterobacteriaceae and E. coli in spinach and rocket (arugula) cultivated in Sweden in 2014–2016 [ 60 ].…”

“…Despite this low prevalence and poor fitness on lettuce crops, EcO157 has caused numerous outbreaks of disease attributed to lettuce in the USA, Canada and Europe [ 16 , 18 , 30 – 32 ]. Additionally, lettuce-associated outbreaks of STEC in the USA follow a seasonal pattern as infections occur more frequently from lettuce harvested in the fall on the West coast of California and in the late winter-early spring in the Southeastern part of California and in Arizona [ 33 , 34 ].…”

Bacteriophages and Food Production: Biocontrol and Bio-Preservation Options for Food Safety

“…The bacteriophage β carrying the tox gene encoding diphtheria toxin for example is transmitted to Corynebacterium diphtheriae via phage horizontal gene transfer (HGT) [ 34 ]. Shiga toxin can also be transferred by HGT amongst members of the Enterobacteriaceae via phage activity where Shiga toxin-producing E. coli O157:H7 (STEC O157:H7) is a significant cause of foodborne disease [ 81 ]. Staphylococcus food poisoning is commonly the result of enterotoxin A produced by Staphylococcal species.…”

Shiga toxin-producing Escherichia coli outbreaks in California’s leafy greens production continuum

“…Ruminants, primarily cattle, are considered a significant reservoir for STEC, which can shed pathogens and directly or indirectly contaminate the irrigation water, runoff, or dust in the environment (Astill et al, 2020). Although the route of transmission from cattle to produce is unknown, plausible ways in which implicated leafy greens have become contaminated, including runoff from these nearby lands, direct transmission from animal operations to leafy green production fields, and application of agricultural water contaminated with fecal material (Álvarez et al, 2019;Astill et al, 2020). A comparison of pathogens of native wildlife found that the relative abundance of pathogen shedding was approximately 5% positivity rate of E. coli O 157:H7 for both cattle and wild pigs (Liao et al, 2021).…”