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.

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 LeafByte: A mobile application that measures leaf area and herbivory quickly and accurately

2019 ◽  
Author(s):  
Zoe L. Getman-Pickering ◽  
Adam T. Campbell ◽  
Nicholas Aflitto ◽  
Todd A. Ugine ◽  
Ari Grele ◽  
...  
Keyword(s):  
Leaf Area ◽  
Plant Tissue ◽  
Mobile Application ◽  
Assessment Tools ◽  
Leaf Damage ◽  
Plant Science ◽  
List Type ◽  
Visual Estimation ◽  
Herbivore Interactions ◽  
Plant Herbivore

AbstractIn both basic and applied studies, quantification of herbivory on foliage is a key metric in characterizing plant-herbivore interactions, which underpin many ecological, evolutionary, and agricultural processes. Current methods of quantifying herbivory are slow or inaccurate. We present LeafByte, a free iOS application for measuring leaf area and herbivory. LeafByte can save data automatically, read and record barcodes, handle both light and dark colored plant tissue, and be used non-destructively.We evaluate its accuracy and efficiency relative to existing herbivory assessment tools.LeafByte has the same accuracy as ImageJ, the field standard, but is 50% faster. Other tools, such as BioLeaf and grid quantification, are quick and accurate, but limited in the information they can provide. Visual estimation is quickest, but it only provides a coarse measure of leaf damage and tends to overestimate herbivory.LeafByte is a quick and accurate means of measuring leaf area and herbivory, making it a useful tool for research in fields such as ecology, entomology, agronomy, and plant science.

scholarly journals Plant Lesions Promote the Rapid Multiplication of Escherichia coli O157:H7 on Postharvest Lettuce

2008 ◽  
Vol 74 (17) ◽  
pp. 5285-5289 ◽  
Author(s):  
M. T. Brandl
Keyword(s):  
Escherichia Coli ◽  
Tissue Damage ◽  
Plant Tissue ◽  
Soft Rot ◽  
The United States ◽  
Leafy Vegetables ◽  
Physiological Disorder ◽  
E Coli ◽  
Critical Control Points ◽  
Population Sizes

ABSTRACT Several outbreaks of Escherichia coli O157:H7 infections have been associated with minimally processed leafy vegetables in the United States. Harvesting and processing cause plant tissue damage. In order to assess the role of plant tissue damage in the contamination of leafy greens with E. coli O157:H7, the effect of mechanical, physiological, and plant disease-induced lesions on the growth of this pathogen on postharvest romaine lettuce was investigated. Within only 4 h after inoculation, the population sizes of E. coli O157:H7 increased 4.0-, 4.5-, and 11.0-fold on lettuce leaves that were mechanically bruised, cut into large pieces, and shredded into multiple pieces, respectively. During the same time, E. coli O157:H7 population sizes increased only twofold on leaves that were left intact after harvest. Also, the population size of E. coli O157:H7 was 27 times greater on young leaves affected by soft rot due to infection by Erwinia chrysanthemi than on healthy middle-aged leaves. Confocal microscopy revealed that leaf tip burn lesions, which are caused by a common physiological disorder of lettuce, harbored dense populations of E. coli O157:H7 cells both internally and externally. Investigation of the colonization of cut lettuce stems by E. coli O157:H7 showed that the pathogen grew 11-fold over 4 h of incubation after its inoculation onto the stems, from which large amounts of latex were released. The results of this study indicate that plant tissue damage of various types can promote significant multiplication of E. coli O157:H7 over a short time and suggest that harvesting and processing are critical control points in the prevention or reduction of E. coli O157:H7 contamination of lettuce.

Sensitivity of Selected Vegetable and Weed Seedlings to Ultraviolet-B Radiation

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 480e-480
Author(s):  
Nancy H. Furness ◽  
Mahesh K. Upadhyaya ◽  
Douglas P. Ormrod
Keyword(s):  
Brassica Oleracea ◽  
Leaf Area ◽  
Spinacia Oleracea ◽  
Relative Sensitivity ◽  
Amaranthus Retroflexus ◽  
Ultraviolet B ◽  
Seedling Height ◽  
Fresh Weight ◽  
Stellaria Media ◽  
Green Foxtail

Relative sensitivity of selected vegetable and weed seedlings to ultraviolet-B (UV-B) radiation (280–320 nm) was investigated. Seedlings were grown for 4 weeks in a greenhouse, in chambers equipped with UV-B-emitting fluorescent tubes and Mylar (control) and cellulose acetate (UV-B) filters. UV-B radiation reduced seedling height, leaf area, and leaf fresh weight in tomato (Lycopersicon esculentum `Cour Di Bue'), broccoli (Brassica oleracea var. Italica `Purple Sprouting'), cabbage (Brassica oleracea var. Capitata `Red Drumhead'), and cucumber (Cucumis sativus `Straight Eight'), leaf area and leaf fresh weight in beet (Beta vulgaris `Cylindra' and `Early Wonder'), seedling height and leaf area in spinach (Spinacia oleracea `Long Standing Bloomsdale'), lettuce (Lactuca sativa ``Red Salad Bowl Everest') and `Savoy' cabbage, and seedling height in `Chinese Tip Top' cabbage and lettuce (`Saladin'). `Winterton' cabbage was not affected. UV-B radiation decreased leaf area and leaf fresh weight in common chickweed (Stellaria media) and corn spurry (Spergula arvensis) and seedling height in green foxtail (Setaria viridis) and redroot pigweed (Amaranthus retroflexus). Tillering was stimulated in response to UV-B in green foxtail. There was no effect of UV-B on lady's-thumb (Polygonum persicaria) growth. Leaf number was not affected by exposure to UV-B in any species. The differential morphological sensitivity of vegetable and weed seedlings may result in altered competitive relationships under enhanced UV-B levels expected with the depletion of the earth's ozone layer.

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.

scholarly journals PSIV-11 Effects of very low-dose antibiotics on gene expression profiles in ileal mucosa of weaned pigs infected with a pathogenic E. coli

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 286-286
Author(s):  
Kwangwook Kim ◽  
Sungbong Jang ◽  
Yanhong Liu
Keyword(s):  
Gene Expression ◽  
Systemic Inflammation ◽  
Low Dose ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Post Inoculation ◽  
Growth Promoter ◽  
Weaned Pigs ◽  
Ileal Mucosa ◽  
E Coli

Abstract Our previous studies have shown that supplementation of low-dose antibiotic growth promoter (AGP) exacerbated growth performance and systemic inflammation of weaned pigs infected with pathogenic Escherichia coli (E. coli). The objective of this experiment, which is extension of our previous report, was to investigate the effect of low-dose AGP on gene expression in ileal mucosa of weaned pigs experimentally infected with F18 E. coli. Thirty-four pigs (6.88 ± 1.03 kg BW) were individually housed in disease containment rooms and randomly allotted to one of three treatments (9 to 13 pigs/treatment). The three dietary treatments were control diet (control), and 2 additional diets supplemented with 0.5 or 50 mg/kg of AGP (carbadox), respectively. The experiment lasted 18 d [7 d before and 11 d after first inoculation (d 0)]. The F18 E. coli inoculum was orally provided to all pigs with the dose of 1010 cfu/3 mL for 3 consecutive days. Total RNA [4 to 6 pigs/treatment on d 5; 5 to 7 pigs/treatment on 11 post-inoculation (PI)] was extracted from ileal mucosa to analyze gene expression profiles by Batch-Tag-Seq. The modulated differential gene expression were defined by 1.5-fold difference and a cutoff of P < 0.05 using limma-voom package. All processed data were statistically analyzed and evaluated by PANTHER classification system to determine the biological process function of genes in these lists. Compared to control, supplementation of recommended-dose AGP down-regulated genes related to inflammatory responses on d 5 and 11 PI; whereas, feeding low-dose AGP up-regulated genes associated with negative regulation of metabolic process on d 5, but down-regulated the genes related to immune responses on d 11 PI. The present observations support adverse effects of low-dose AGP in our previous study, indicated by exacerbated the detrimental effects of E. coli infection on pigs’ growth rate, diarrhea and systemic inflammation.

187 Effects of Oligosaccharide-based Polymer on Growth Performance, Diarrhea, and Fecal β-hemolytic Coliforms in Weanling Pigs Experimentally Infected with a Pathogenic E. coli

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 90-90
Author(s):  
Kwangwook Kim ◽  
Yijie He ◽  
Cynthia Jinno ◽  
Seijoo Yang ◽  
Xunde Li ◽  
...  
Keyword(s):  
Growth Performance ◽  
Feed Efficiency ◽  
Basal Diet ◽  
Watery Diarrhea ◽  
Experimental Unit ◽  
Post Inoculation ◽  
Weaned Pigs ◽  
E Coli ◽  
Diet Control ◽  
Dietary Treatments

Abstract The objective of this experiment was to investigate dietary supplementation of oligosaccharide-based polymer on growth performance, diarrhea, and fecal β-hemolytic coliforms of weaned pigs experimentally infected with a pathogenic F18 Escherichia coli (E. coli). Forty-eight pigs (7.23 ± 1.11 kg BW) were individually housed in disease containment rooms and randomly allotted to one of four treatments with 12 replicate pigs per treatment. The four dietary treatments were a nursery basal diet (control), and 3 additional diets supplemented with 50 mg/kg Mecadox (AGP), 10 or 20 mg/kg of oligosaccharide-based polymer. The experiment lasted 18 d [7 d before and 11 d after the first inoculation (d 0)]. The doses of F18 E. coli inoculum were 1010 cfu/3 mL oral dose daily for 3 days. Growth performance was measured on d -7 to 0 before inoculation, and d 0 to 5 and 5 to 11 post-inoculation (PI). Diarrhea score (DS; 1, normal, to 5, watery diarrhea) was daily recorded for each pig. Fecal samples were collected on d 2, 5, 8, and 11 PI to test the percentage of β-hemolytic coliforms in total coliforms. All data were analyzed by ANOVA using the PROC MIXED of SAS with pig as the experimental unit. Inclusion of oligosaccharide-based polymer linearly increased (P < 0.05) ADFI on d 0 to 5 PI, and feed efficiency on d 0 to 5 PI and d 5 to 11 PI (P = 0.07), compared with the control. Supplementation of AGP or oligosaccharide-based polymer reduced (P < 0.01) frequency of diarrhea of pigs from d 0 to 11 PI. No differences were observed in overall growth performance and percentage of fecal β-hemolytic coliforms on d 8 PI among pigs in AGP and oligosaccharide-based polymer treatments. In conclusion, supplementation of oligosaccharide-based polymer enhanced feed efficiency and reduced diarrhea of weaned pigs infected with a pathogenic E. coli.

Effect of plant systemic resistance elicited by biological and chemical inducers on the colonization of the lettuce and basil leaf apoplast by Salmonella enterica

2021 ◽  
Author(s):  
L. Chalupowicz ◽  
S. Manulis-Sasson ◽  
I. Barash ◽  
Y. Elad ◽  
D. Rav-David ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Microbial Contamination ◽  
Mitigation Strategies ◽  
Enteric Pathogens ◽  
Leafy Vegetables ◽  
Population Increase ◽  
Systemic Resistance ◽  
Post Inoculation ◽  
Proof Of Concept ◽  
Leaf Apoplast

Mitigation strategies to prevent microbial contamination of crops are lacking. We tested the hypothesis that induction of plant systemic resistance by biological (ISR) and chemical (SAR) elicitors reduces endophytic colonization of leaves by Salmonella enterica serovars Senftenberg and Typhimurium. S . Senftenberg had greater endophytic fitness than S . Typhimurium in basil and lettuce. The apoplastic population sizes of serovars Senftenberg and Typhimurium in basil and lettuce, respectively, were significantly reduced approximately 10- to 100-fold by root treatment with microbial inducers of systemic resistance compared with the H 2 O treatment. Rhodotorula glutinis effected the lowest population increase of S . Typhimurium in lettuce (120-fold) and S . Senftenberg in basil leaves (60-fold) compared with the H 2 O treatment over 10 days post-inoculation. Trichoderma harzianum and Pichia guilliermondii did not have any significant effect on S . Senftenberg in the basil apoplast. The chemical elicitors acidobenzolar-S-methyl and DL-β-amino-butyric acid inhibited S . Typhimurium multiplication in the lettuce apoplast 10- and 2-fold, respectively, compared with H 2 O-treated plants. All ISR and SAR inducers applied to lettuce roots in this study increased leaf expression of the defense gene PR1 , as did Salmonella apoplastic colonization in H 2 O-treated lettuce plants. Remarkably, both acidobenzolar-S-methyl- and R. glutinis -upregulation of PR1 was repressed by the presence of Salmonella in the leaves. However, enhanced PR1 expression was sustained longer and at greater levels upon elicitor treatment than by Salmonella induction alone. These results serve as proof of concept that priming of plant immunity may provide an intrinsic hurdle against the endophytic establishment of enteric pathogens in leafy vegetables. Importance Fruit and vegetables consumed raw have become an important vehicle of foodborne illness despite a continuous effort to improve their microbial safety. Salmonella enterica has caused numerous recalls and outbreaks of infection associated with contaminated leafy vegetables. Evidence is increasing that enteric pathogens can reach the leaf apoplast where they confront plant innate immunity. Plants may be triggered for induction of their defense signaling pathways by exposure to chemical or microbial elicitors. This priming for recognition of microbes by plant defense pathways has been used to inhibit plant pathogens and limit disease. Given that current mitigation strategies are insufficient in preventing microbial contamination of produce and associated outbreaks, we investigated the effect of plant induced resistance on S. enterica colonization of the lettuce and basil leaf apoplast in order to gain a proof of concept for the use of such an intrinsic approach to inhibit human pathogens in leafy vegetables.

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