Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli on Vegetable Seeds Contaminated by Direct Contact with Artificially Inoculated Soil during Germination

2020 ◽  
Vol 83 (7) ◽  
pp. 1218-1226
Author(s):  
YUE CUI ◽  
DA LIU ◽  
JINRU CHEN
Keyword(s):  
Escherichia Coli ◽  
Direct Contact ◽  
Bacterial Pathogens ◽  
Enterohemorrhagic Escherichia Coli ◽  
Tissue Samples ◽  
Tomato Seedlings ◽  
Tissue Sections ◽  
Germination Process ◽  
The Mean ◽  
Alfalfa Sprouts

ABSTRACT Contaminated vegetable seeds have been identified as a potential source of foodborne bacterial pathogens. This study was undertaken to observe the behavior of Salmonella and enterohemorrhagic Escherichia coli (EHEC) on vegetable seeds, contaminated by direct contact with artificially inoculated soil, during germination. Sterile sandy soil inoculated with lyophilized cells of four individual strains of Salmonella or EHEC (three O157:H7 strains and one O104:H4 strain) was mixed with sanitized seeds (2 g) of alfalfa, fenugreek, lettuce, and tomato at 20°C for 1 h. The contaminated seeds were germinated on 1% water agar at 25°C for 9 days in the dark. Populations of Salmonella and EHEC on various tissues (seed coat, root, cotyledon, and stem, etc.) of sprouts and seedlings were determined every other day over the germination period. Overall, 70.4 and 72.4% of collected tissue samples (n = 544) tested positive for Salmonella and EHEC, respectively. In general, the mean populations of Salmonella and EHEC on sprout and seedling tissues increased with the prolongation of germination time. Seed coats had the highest bacterial counts (4.00 to 4.06 log CFU/0.01 g), followed by the root (3.36 to 3.38 log CFU/0.01 g), cotyledon (3.13 to 3.38 log CFU/0.01 g), and stem tissues (2.67 to 2.84 log CFU/0.01 g). On average, tissue sections of fenugreek sprouts and lettuce seedlings had significantly higher (P < 0.05) numbers of Salmonella and EHEC cells than that of alfalfa sprouts and tomato seedlings. Data suggest that the growth and dissemination of Salmonella and EHEC cells on alfalfa, fenugreek, lettuce, and tomato sprout and seedling tissues are influenced by the type of vegetable seeds and sprout and seedling tissues involved. The study provides useful information on the fate of two important foodborne bacterial pathogens on selected vegetable seeds, contaminated by direct contact with inoculated soil, during the germination process. HIGHLIGHTS

scholarly journals Fate of Salmonella enterica and Enterohemorrhagic Escherichia coli Cells Artificially Internalized into Vegetable Seeds during Germination

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Da Liu ◽  
Yue Cui ◽  
Ronald Walcott ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Bacterial Pathogens ◽  
Bacterial Species ◽  
Enterohemorrhagic Escherichia Coli ◽  
Human Pathogens ◽  
Gastrointestinal Infections ◽  
Tissue Samples ◽  
Content Type ◽  
Vegetable Seed

ABSTRACTVegetable seeds contaminated with bacterial pathogens have been linked to fresh-produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior ofSalmonella entericaand enterohemorrhagicEscherichia coli(EHEC) cells artificially internalized into vegetable seeds during the germination process. Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains ofSalmonellaor EHEC. Contaminated seeds were germinated at 25°C for 9 days, and different sprout/seedling tissues were microbiologically analyzed every other day. The internalization ofSalmonellaand EHEC cells into vegetable seeds was confirmed by the absence of pathogens in seed-rinsing water and the presence of pathogens in seed homogenates after postinternalization seed surface decontamination. Results show that 317 (62%) and 343 (67%) of the 512 collected sprout/seedling tissue samples were positive forSalmonellaand EHEC, respectively. The averageSalmonellapopulations were significantly larger (P< 0.05) than the EHEC populations. Significantly largerSalmonellapopulations were recovered from the cotyledon and seed coat tissues, followed by the root tissues, but the mean EHEC populations from all sampled tissue sections were statistically similar, except in pregerminated seeds. ThreeSalmonellaand two EHEC strains had significantly larger cell populations on sprout/seedling tissues than other strains used in the study.Salmonellaand EHEC populations from fenugreek and alfalfa tissues were significantly larger than those from tomato and lettuce tissues. The study showed the fate of internalized human pathogens on germinating vegetable seeds and sprout/seedling tissues and emphasized the importance of using pathogen-free seeds for sprout production.IMPORTANCEThe internalization of microorganisms into vegetable seeds could occur naturally and represents a possible pathway of vegetable seed contamination by human pathogens. The present study investigated the ability of two important bacterial pathogens,Salmonellaand enterohemorrhagicEscherichia coli(EHEC), when artificially internalized into vegetable seeds, to grow and disseminate along vegetable sprouts/seedlings during germination. The data from the study revealed that the pathogen cells artificially internalized into vegetable seeds caused the contamination of different tissues of sprouts/seedlings and that pathogen growth on germinating seeds is bacterial species and vegetable seed-type dependent. These results further stress the necessity of using pathogen-free vegetable seeds for edible sprout production.

scholarly journals Reduction of Carriage of Enterohemorrhagic Escherichia coli O157:H7 in Cattle by Inoculation with Probiotic Bacteria

1998 ◽  
Vol 36 (3) ◽  
pp. 641-647 ◽  
Author(s):  
Tong Zhao ◽  
Michael P. Doyle ◽  
Barry G. Harmon ◽  
Cathy A. Brown ◽  
P. O. Eric Mueller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Probiotic Bacteria ◽  
Escherichia Coli O157 ◽  
Bacterial Isolates ◽  
Intestinal Tissue ◽  
Tissue Samples ◽  
E Coli ◽  
Observation Period

Bacteria inhibitory to Escherichia coli O157:H7 were isolated from cattle and evaluated for their potential for reducing carriage of E. coli O157:H7 in calves. Eighteen of 1,200 bacterial isolates from cattle feces and intestinal tissue samples were screened and determined to inhibit the growth of E. coliO157:H7 in vitro. Seventeen of the isolates were E. coli and one was Proteus mirabilis. None produced Shiga toxin. Genomic DNA fingerprinting by pulsed-field gel electrophoresis revealed 13 distinguishable profiles among the 18 isolates. Two calves inoculated perorally with a mixture of all 18 isolates (1010 CFU) appeared to be normal and did not develop signs of clinical disease throughout a 25- to 27-day observation period. These bacteria colonized segments of the gastrointestinal tract and were in feces at the termination of the experiment (25 and 27 days postinoculation) at levels of 50 to 200 CFU/g. Fifteen cannulated calves were studied to determine the efficiency of the probiotic bacteria in reducing or eliminating the carriage of E. coli O157:H7. Nine calves served as controls, with each animal receiving perorally 1010 CFU ofE. coli O157:H7. E. coliO157:H7 was detected intermittently in the rumen samples from all control animals throughout 3 weeks postinoculation, whereasE. coli O157:H7 was shed at various levels in feces continuously throughout the experiment (mean, 28 days).E. coli O157:H7 was isolated from the rumens and colons of eight of nine and nine of nine calves, respectively, at the termination of the study. Six calves each received perorally 1010 CFU of probiotic bacteria and then 2 days later received 1010 CFU of E. coli O157:H7.E. coli O157:H7 was detected in the rumen for only 9 days postinoculation in two animals, for 16 days in one animal, for 17 days in two animals, and for 29 days in one animal. E. coli O157:H7 was detected in feces for only 11 days postinoculation in one animal, for 15 days in one animal, for 17 days in one animal, for 18 days in one animal, for 19 days in one animal, and for 29 days in one animal. At the end of the experiment (mean, 30 days), E. coli O157:H7 was not recovered from the rumen of any of the six animals treated with probiotic bacteria; however, E. coli O157:H7 was recovered from the feces of one of the animals. This animal was fasted twice postinoculation. These studies indicate that selected probiotic bacteria administered to cattle prior to exposure to E. coli O157:H7 can reduce the level of carriage ofE. coli O157:H7 in most animals.

Behavior of Enterohemorrhagic Escherichia coli O157:H7 on Alfalfa Sprouts during the Sprouting Process as Influenced by Treatments with Various Chemicals

1999 ◽  
Vol 62 (8) ◽  
pp. 850-856 ◽  
Author(s):  
PETER J. TAORMINA ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Cold Storage ◽  
Treatment Method ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Chemical Treatments ◽  
Alfalfa Sprouts ◽  
Germinated Seeds ◽  
Alfalfa Seeds

The behavior of Escherichia coli O157:H7 on alfalfa seeds subjected to conditions similar to those used commercially to grow and market sprouts as it is affected by applications of NaOCl, Ca(OCl)2, acidified NaClO2, acidified ClO2, Na3PO4, Vegi-Clean, Tsunami, Vortexx, or H2O2 at various stages of the sprouting process was determined. Application of 2,000 ppm of NaOCl, 200 and 2,000 ppm of Ca(OCl)2, 500 ppm of acidified ClO2, 10,000 ppm of Vegi-Clean, 80 ppm of Tsunami, or 40 and 80 ppm of Vortexx to germinated seeds significantly reduced the population of E. coli O157:H7. With the exception of acidified NaOCl2 at 1,200 ppm, spray applications of these chemicals did not significantly reduce populations or control the growth of E. coli O157:H7 on alfalfa sprouts during the sprouting process. Populations of E. coli on alfalfa sprouts peaked at 6 to 7 log10 CFU/g 48 h after initiation of the sprouting process and remained stable despite further spraying with chemicals. The population of E. coli O157:H7 on sprouts as they entered cold storage at 9 ± 2°C remained essentially unchanged for up to 6 days. None of the chemical treatments evaluated was able to eliminate or satisfactorily reduce E. coli O157:H7 on alfalfa seeds and sprouts. Observations on the ability of E. coli O157:H7 to grow during production of alfalfa sprouts not subjected to chemical treatments are similar to those from a previous study in our laboratory on the behavior of Salmonella Stanley. Our results do not reveal a chemical treatment method to eliminate the pathogen from alfalfa sprouts. We have demonstrated that currently recommended procedures for sanitizing alfalfa seeds fail to eliminate E. coli O157:H7 and that the pathogen can grow to populations exceeding 7 log10 CFU/g of sprouts produced using techniques not dissimilar to those used in the sprout industry.

scholarly journals Differential Attachment of Salmonella enterica and Enterohemorrhagic Escherichia coli to Alfalfa, Fenugreek, Lettuce, and Tomato Seeds

2017 ◽  
Vol 83 (7) ◽  
Author(s):  
Yue Cui ◽  
Ronald Walcott ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Bacterial Pathogens ◽  
Surface Characteristics ◽  
Enterohemorrhagic Escherichia Coli ◽  
Unit Weight ◽  
Plate Count ◽  
Fenugreek Seeds ◽  
Content Type ◽  
Fungicide Treatment ◽  
Tomato Seeds

ABSTRACT Vegetable seeds have the potential to disseminate and transmit foodborne bacterial pathogens. This study was undertaken to assess the abilities of selected Salmonella and enterohemorrhagic Escherichia coli (EHEC) strains to attach to fungicide-treated versus untreated, and intact versus mechanically damaged, seeds of alfalfa, fenugreek, lettuce, and tomato. Surface-sanitized seeds (2 g) were exposed to four individual strains of Salmonella or EHEC at 20°C for 5 h. Contaminated seeds were rinsed twice, each with 10 ml of sterilized water, before being soaked overnight in 5 ml of phosphate-buffered saline at 4°C. The seeds were then vortexed vigorously for 1 min, and pathogen populations in seed rinse water and soaking buffer were determined using a standard plate count assay. In general, the Salmonella cells had higher attachment ratios than the EHEC cells. Lettuce seeds by unit weight had the highest numbers of attached Salmonella or EHEC cells, followed by tomato, alfalfa, and fenugreek seeds. In contrast, individual fenugreek seeds had more attached pathogen cells, followed by lettuce, alfalfa, and tomato seeds. Significantly more Salmonella and EHEC cells attached to mechanically damaged seeds than to intact seeds (P < 0.05). Although, on average, significantly more Salmonella and EHEC cells were recovered from untreated than fungicide-treated seeds (P < 0.05), fungicide treatment did not significantly affect the attachment of individual bacterial strains to vegetable seeds (P > 0.05), with a few exceptions. This study fills gaps in the current body of literature and helps explain bacterial interactions with vegetable seeds with differing surface characteristics. IMPORTANCE Vegetable seeds, specifically sprout seeds, have the potential to disseminate and transmit foodborne bacterial pathogens. This study investigated the interaction between two important bacterial pathogens, i.e., Salmonella and EHEC, and vegetable seeds with differing surface characteristics. This research helps understand whether seed surface structure, integrity, and fungicide treatment affect the interaction between bacterial cells and vegetable seeds.

Discovery of intracellular 2,8 dihydroxyadenine crystals in bovine lymphatic and hepatic cells

1987 ◽  
Vol 45 ◽  
pp. 906-907
Author(s):  
W. E. Rigsby ◽  
D. M. Hinton ◽  
V. J. Hurst ◽  
P. C. McCaskey
Keyword(s):  
Polarized Light ◽  
Paraffin Sections ◽  
Tissue Samples ◽  
Whole Cells ◽  
Tissue Sections ◽  
Hepatic Cells ◽  
Slaughter House ◽  
Mammalian Tissues ◽  
Carbon Coated ◽  
Cellular Components

Crystalline intracellular inclusions are rarely seen in mammalian tissues and are often difficult to positively identify. Lymph node and liver tissue samples were obtained from two cows which had been rejected at the slaughter house due to the abnormal appearance of these organs in the animals. The samples were fixed in formaldehyde and some of the fixed material was embedded in paraffin. Examination of the paraffin sections with polarized light microscopy revealed the presence of numerous crystals in both hepatic and lymph tissue sections. Tissue sections were then deparaffinized in xylene, mounted, carbon coated, and examined in a Phillips 505T SEM equipped with a Tracor Northern X-ray Energy Dispersive Spectroscopy (EDS) system. Crystals were obscured by cellular components and membranes so that EDS spectra were only obtainable from whole cells. Tissue samples which had been fixed but not paraffin-embedded were dehydrated, embedded in Spurrs plastic, and sectioned.

scholarly journals Rapid brain structure and tumour margin detection on whole frozen tissue sections by fast multiphotometric mid-infrared scanning

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tim Kümmel ◽  
Björn van Marwick ◽  
Miriam Rittel ◽  
Carina Ramallo Guevara ◽  
Felix Wühler ◽  
...  
Keyword(s):  
Imaging System ◽  
Frozen Section ◽  
Computational Effort ◽  
Primary Hepatocellular Carcinoma ◽  
Measuring System ◽  
Sufficient Information ◽  
Tissue Samples ◽  
Mid Infrared ◽  
Tissue Sections ◽  
Frozen Tissue

AbstractFrozen section analysis is a frequently used method for examination of tissue samples, especially for tumour detection. In the majority of cases, the aim is to identify characteristic tissue morphologies or tumour margins. Depending on the type of tissue, a high number of misdiagnoses are associated with this process. In this work, a fast spectroscopic measurement device and workflow was developed that significantly improves the speed of whole frozen tissue section analyses and provides sufficient information to visualize tissue structures and tumour margins, dependent on their lipid and protein molecular vibrations. That optical and non-destructive method is based on selected wavenumbers in the mid-infrared (MIR) range. We present a measuring system that substantially outperforms a commercially available Fourier Transform Infrared (FT-IR) Imaging system, since it enables acquisition of reduced spectral information at a scan field of 1 cm2 in 3 s, with a spatial resolution of 20 µm. This allows fast visualization of segmented structure areas with little computational effort. For the first time, this multiphotometric MIR system is applied to biomedical tissue sections. We are referencing our novel MIR scanner on cryopreserved murine sagittal and coronal brain sections, especially focusing on the hippocampus, and show its usability for rapid identification of primary hepatocellular carcinoma (HCC) in mouse liver.

scholarly journals Influence of Bacterial Competitors on Salmonella enterica and Enterohemorrhagic Escherichia coli Growth in Microbiological Media and Attachment to Vegetable Seeds

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 285
Author(s):  
Da Liu ◽  
Ronald Walcott ◽  
Kevin Mis Solval ◽  
Jinru Chen
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Salmonella Enterica ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Bacterium ◽  
Enterohemorrhagic Escherichia Coli ◽  
Biocontrol Agents ◽  
Human Pathogens ◽  
Bacterial Strains ◽  
Pathogen Populations

Interests in using biological agents for control of human pathogens on vegetable seeds are rising. This study evaluated whether probiotic bacterium Lactobacillus rhamnosus GG, bacterial strains previously used as biocontrol agents in plant science, as well as a selected plant pathogen could compete with foodborne human pathogens, such as Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC), for growth in microbiological media and attachment to vegetable seeds; and to determine whether the metabolites in cell-free supernatants of competitive bacterial spent cultures could inhibit the growth of the two pathogens. The results suggest that the co-presence of competitive bacteria, especially L. rhamnosus GG, significantly (p < 0.05) inhibited the growth of Salmonella and EHEC. Cell-free supernatants of L. rhamnosus GG cultures significantly reduced the pathogen populations in microbiological media. Although not as effective as L. rhamnosus GG in inhibiting the growth of Salmonella and EHEC, the biocontrol agents were more effective in competing for attachment to vegetable seeds. The study observed the inhibition of human bacterial pathogens by competitive bacteria or their metabolites and the competitive attachment to sprout seeds among all bacteria involved. The results will help strategize interventions to produce vegetable seeds and seed sprouts free of foodborne pathogens.

scholarly journals Feasibility of balloon-based endobiliary radiofrequency ablation under cholangioscopy guidance in a swine model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tadahisa Inoue ◽  
Hiromu Kutsumi ◽  
Mayu Ibusuki ◽  
Masashi Yoneda
Keyword(s):  
Radiofrequency Ablation ◽  
Adverse Events ◽  
Swine Model ◽  
Biliary Strictures ◽  
Tissue Samples ◽  
Ablation Area ◽  
Mucosal Changes ◽  
The Mean ◽  
Preliminary Study

AbstractAlthough endobiliary radiofrequency ablation (RFA) has demonstrated considerable potential for the treatment of biliary strictures, conventional catheter RFA has several limitations. This study aimed to evaluate the feasibility of a novel cholangioscopy (CS)-guided balloon-based RFA procedure in vivo using a swine model. CS-guided balloon-RFA was performed under endoscopic retrograde cholangiography guidance at target temperatures of 60 ℃ or 70 ℃, which were maintained for 60 s. We evaluated the technical feasibility, adverse events, and histological effects associated with the procedure. Twelve sites were ablated in seven miniature pigs. The CS-guided balloon-RFA procedure was technically successful in all cases without any hindrance. Mucosal changes could be detected during RFA, and the ablation area was identified on CS. Necropsy was performed in four pigs on the same day as the procedure: the tissue samples showed coagulative necrosis, and the entire internal circumference of the bile duct was uniformly ablated. The mean lengths of the ablation area in the samples ablated at 60 °C and 70 °C were 20.64 and 22.18 mm, respectively, while the mean depths were 3.46 and 5.07 mm, respectively. The other three pigs were reared and euthanized and autopsied 35 days after the procedure. The site to be ablated had replaced the granulation tissue and fibrotic changes. No adverse events were observed in any case. CS-guided balloon-RFA appears to be a promising option for treating biliary strictures. This preliminary study could pave the way for the evaluation of this procedure in future human clinical trials.

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