Season and Species: Two Possible Hurdles for Reducing the Food Safety Risk of Escherichia coli O157 Contamination of Leafy Vegetables

2019 ◽  
Vol 82 (2) ◽  
pp. 247-255 ◽  
Author(s):  
KARIN SÖDERQVIST ◽  
ANNA KARIN ROSBERG ◽  
SOFIA BOQVIST ◽  
BEATRIX ALSANIUS ◽  
LARS MOGREN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Shelf Life ◽  
Spinacia Oleracea ◽  
Growing Season ◽  
Leafy Vegetables ◽  
Production Chain ◽  
Safety Risk ◽  
E Coli ◽  
Food Safety Risk

ABSTRACT The food safety risk of Shiga toxin–producing Escherichia coli (STEC) infection per serving of leafy vegetables was investigated using a quantitative microbial risk assessment (QMRA) approach. The estimated level of E. coli O157 contamination was based on observed numbers of Enterobacteriaceae and E. coli on leafy vegetables grown and processed in southern Sweden from 2014 to 2016. Samples were collected before harvest, after washing, and at the end of shelf life. The observed counts were combined with data on the ratio of E. coli to E. coli O157 taken from earlier studies to estimate the probability of illness. The risks of STEC infection associated with species, either spinach (Spinacia oleracea) or rocket (Diplotaxis tenuifolia), growing season (spring or autumn), and washing (washed or not washed) were then evaluated. The results indicated that leafy vegetable species and growing season could be possible hurdles for reducing the food safety risk of STEC infection. At harvest, the probability of infection was 87% lower when consuming rocket compared with spinach and 90% lower when consuming leafy vegetables grown in spring compared with autumn. These relative risk reductions remained consistent even with other serving sizes and dose-response models. The lowest risk of STEC infection was associated with leafy vegetables early in the production chain, i.e., before harvest, while the risk increased during storage and processing. Consequently, the highest risk was observed when leafy vegetables were consumed at the end of shelf life. Washing had no effect on the food safety risk of STEC infection in this study. To improve the quality of QMRA, there is a need for additional data on the relationship between indicator organisms that can be easily enumerated (e.g., E. coli and Enterobacteriaceae) and E. coli strains that can cause STEC infection (e.g., E. coli O157) but are difficult to identify in food samples such as leafy vegetables.

scholarly journals Size Matters: Biological and Food Safety Relevance of Leaf Damage for Colonization of Escherichia coli O157:H7 gfp+

2021 ◽  
Vol 11 ◽  
Author(s):  
Emina Mulaosmanovic ◽  
Sofia T. Windstam ◽  
Ivar Vågsholm ◽  
Beatrix W. Alsanius
Keyword(s):  
Food Safety ◽  
Leaf Area ◽  
Plant Tissue ◽  
Spinacia Oleracea ◽  
Leafy Vegetables ◽  
Leaf Damage ◽  
Post Inoculation ◽  
Depth Of Invasion ◽  
Damage Level ◽  
E Coli

This study examined the biological and food safety relevance of leaf lesions for potential invasion of food pathogens into the plant tissue (internalization). This was done by determining the role of artificial leaf damage in terms of damaged leaf area on proliferation of E. coli O157:H7 gfp+. In a two-factorial experiment, unwashed fresh baby leaf spinach (Spinacia oleracea L.) was subjected to four damage levels (undamaged, low, moderate, high damage; factor 1) and three incubation intervals (0, 1, 2 days post-inoculation; factor 2). Individual leaves were immersed for 15 s in a suspension loaded with E. coli O157:H7 gfp+ (106 CFU × mL–1). The leaves were analyzed individually using image analysis tools to quantify leaf area and number and size of lesions, and using confocal laser scanning and scanning electron microscopy to visualize leaf lesions and presence of the introduced E. coli strain on and within the leaf tissue. Prevalence of E. coli O157:H7 gfp+ was assessed using a culture-dependent technique. The results showed that size of individual lesions and damaged leaf area affected depth of invasion into plant tissue, dispersal to adjacent areas, and number of culturable E. coli O157:H7 gfp+ directly after inoculation. Differences in numbers of the inoculant retrieved from leaf macerate evened out from 2 days post-inoculation, indicating rapid proliferation during the first day post-inoculation. Leaf weight was a crucial factor, as lighter spinach leaves (most likely younger leaves) were more prone to harbor E. coli O157:H7 gfp+, irrespective of damage level. At the high inoculum density used, the risk of consumers’ infection was almost 100%, irrespective of incubation duration or damage level. Even macroscopically intact leaves showed a high risk for infection. These results suggest that the risk to consumers is correlated with how early in the food chain the leaves are contaminated, and the degree of leaf damage. These findings should be taken into account in different steps of leafy green processing. Further attention should be paid to the fate of viable, but non-culturable, shiga-toxigenic E. coli on and in ready-to-eat leafy vegetables.

High prevalence of antimicrobial-resistant Escherichia coli from animals at slaughter: a food safety risk

2012 ◽  
Vol 93 (3) ◽  
pp. 517-526 ◽  
Author(s):  
Sónia Ramos ◽  
Nuno Silva ◽  
Manuela Caniça ◽  
José Luis Capelo-Martinez ◽  
Francisco Brito ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Safety Risk ◽  
High Prevalence ◽  
Food Safety Risk

scholarly journals The Growing Season, but Not the Farming System, Is a Food Safety Risk Determinant for Leafy Greens in the Mid-Atlantic Region of the United States

2015 ◽  
Vol 81 (7) ◽  
pp. 2395-2407 ◽  
Author(s):  
Sasha C. Marine ◽  
Sivaranjani Pagadala ◽  
Fei Wang ◽  
Donna M. Pahl ◽  
Meredith V. Melendez ◽  
...  
Keyword(s):  
United States ◽  
Food Safety ◽  
Growing Season ◽  
Farming System ◽  
The United States ◽  
Atlantic Region ◽  
Content Type ◽  
E Coli ◽  
Leafy Greens ◽  
Food Safety Risk

ABSTRACTSmall- and medium-size farms in the mid-Atlantic region of the United States use varied agricultural practices to produce leafy greens during spring and fall, but the impact of preharvest practices on food safety risk remains unclear. To assess farm-level risk factors, bacterial indicators,Salmonella enterica, and Shiga toxin-producingEscherichia coli(STEC) from 32 organic and conventional farms were analyzed. A total of 577 leafy greens, irrigation water, compost, field soil, and pond sediment samples were collected.Salmonellawas recovered from 2.2% of leafy greens (n= 369) and 7.7% of sediment (n= 13) samples. There was an association betweenSalmonellarecovery and growing season (fall versus spring) (P= 0.006) but not farming system (organic or conventional) (P= 0.920) or region (P= 0.991). No STEC was isolated. In all, 10% of samples were positive forE. coli: 6% of leafy greens, 18% of irrigation water, 10% of soil, 38% of sediment, and 27% of compost samples. Farming system was not a significant factor for levels ofE. colior aerobic mesophiles on leafy greens but was a significant factor for total coliforms (TC) (P< 0.001), with higher counts from organic farm samples. Growing season was a factor for aerobic mesophiles on leafy greens (P= 0.004), with higher levels in fall than in spring. Water source was a factor for all indicator bacteria (P< 0.001), and end-of-line groundwater had marginally higher TC counts than source samples (P= 0.059). Overall, the data suggest that seasonal events, weather conditions, and proximity of compost piles might be important factors contributing to microbial contamination on farms growing leafy greens.

scholarly journals The ComBase initiative

2004 ◽  
Vol 25 (3) ◽  
pp. 32 ◽  
Author(s):  
József Baranyi ◽  
Mark Tamplin ◽  
Tom Ross
Keyword(s):  
Food Safety ◽  
Shelf Life ◽  
Computer Modelling ◽  
Hazard Analysis ◽  
Control Point ◽  
Risk Assessments ◽  
Regulatory Agencies ◽  
Safety Risk ◽  
Critical Control Point ◽  
Food Safety Risk

Food safety professionals in industry, academia and regulatory agencies increasingly use computer modelling tools to improve food safety and shelf life (including the development of Hazard Analysis Critical Control Point (HACCP) plans) and to support microbial food safety risk assessments. Earlier this year, we conducted workshops in Melbourne and Sydney to introduce Australian scientists to one such tool, ComBase, and to provide training in its use

scholarly journals Prevalence and Characterization of Extended-Spectrum β-Lactamase-Producing Antibiotic-Resistant Escherichia coli and Klebsiella pneumoniae in Ready-to-Eat Street Foods

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 850
Author(s):  
Shobha Giri ◽  
Vaishnavi Kudva ◽  
Kalidas Shetty ◽  
Veena Shetty
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Klebsiella Pneumoniae ◽  
Rural Areas ◽  
Significant Risk ◽  
Microbiological Quality ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Extended Spectrum

As the global urban populations increase with rapid migration from rural areas, ready-to-eat (RTE) street foods are posing food safety challenges where street foods are prepared with less structured food safety guidelines in small and roadside outlets. The increased presence of extended-spectrum-β-lactamase (ESBL) producing bacteria in street foods is a significant risk for human health because of its epidemiological significance. Escherichia coli and Klebsiella pneumoniae have become important and dangerous foodborne pathogens globally for their relevance to antibiotic resistance. The present study was undertaken to evaluate the potential burden of antibiotic-resistant E. coli and K. pneumoniae contaminating RTE street foods and to assess the microbiological quality of foods in a typical emerging and growing urban suburb of India where RTE street foods are rapidly establishing with public health implications. A total of 100 RTE food samples were collected of which, 22.88% were E. coli and 27.12% K. pneumoniae. The prevalence of ESBL-producing E. coli and K. pneumoniae was 25.42%, isolated mostly from chutneys, salads, paani puri, and chicken. Antimicrobial resistance was observed towards cefepime (72.9%), imipenem (55.9%), cefotaxime (52.5%), and meropenem (16.9%) with 86.44% of the isolates with MAR index above 0.22. Among β-lactamase encoding genes, blaTEM (40.68%) was the most prevalent followed by blaCTX (32.20%) and blaSHV (10.17%). blaNDM gene was detected in 20.34% of the isolates. This study indicated that contaminated RTE street foods present health risks to consumers and there is a high potential of transferring multi-drug-resistant bacteria from foods to humans and from person to person as pathogens or as commensal residents of the human gut leading to challenges for subsequent therapeutic treatments.

Comparing the Microbiological Status of Pre- and Postharvest Produce from Small Organic Production

2015 ◽  
Vol 78 (6) ◽  
pp. 1072-1080 ◽  
Author(s):  
AIXIA XU ◽  
DONNA M. PAHL ◽  
ROBERT L. BUCHANAN ◽  
SHIRLEY A. MICALLEF
Keyword(s):  
Food Safety ◽  
Organic Production ◽  
Wash Water ◽  
Small Scale ◽  
Organic Farms ◽  
Production Scale ◽  
Safety Risk ◽  
Leafy Greens ◽  
Postharvest Handling ◽  
Food Safety Risk

Consumption of locally, organically grown produce is increasing in popularity. Organic farms typically produce on a small scale, have limited resources, and adopt low technology harvest and postharvest handling practices. Data on the food safety risk associated with hand harvesting, field packing, and packing-house handling with minimal treatment, at this production scale, are lacking. We followed produce from small organic farms from the field through postharvest handling and packing. Pre- and postharvest produce (177 samples) and water (29 samples) were collected and analyzed quantitatively for Escherichia coli, total coliforms (TC), aerobic bacteria (APC), yeasts, molds (M), and enteric pathogens. No pathogens were recovered. E. coli was detected in 3 (3.6%) of 83 preharvest produce samples, 2 (6.3%) of 32 unwashed and 0 of 42 washed postharvest produce samples, and 10 (34.5%) of 29 water samples. No correlation was found between bacterial levels in irrigation water and those on produce. Postharvest handling without washing was a factor for APC and M counts on tomatoes, with lower frequencies postharvest. Postharvest handling with washing was a factor for leafy greens for TC counts, with higher frequencies postharvest. APC (P = 0.03) and yeast (P = 0.05) counts were higher in preharvest than in unwashed postharvest tomatoes. Washed postharvest leafy greens had higher M counts (P = 0.03) and other washed produce had higher TC counts (P = 0.01) than did their preharvest counterparts. Barriers were found to the use of sanitizer in wash water for leafy greens among small farms using organic practices. Hand harvesting and dry handling did not appear to be associated with a significant food safety risk, but washed leafy greens carried higher levels of some microbial indicators, possibly because of the lack of sanitizer in the wash water. The development of resources and materials customized for this sector of growers could enhance dissemination of information on best practices for handling of leafy greens.

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