Surface and Internalized Escherichia coli O157:H7 on Field-Grown Spinach and Lettuce Treated with Spray-Contaminated Irrigation Water

2010 ◽  
Vol 73 (6) ◽  
pp. 1023-1029 ◽  
Author(s):  
MARILYN C. ERICKSON ◽  
CATHY C. WEBB ◽  
JUAN CARLOS DIAZ-PEREZ ◽  
SHARAD C. PHATAK ◽  
JOHN J. SILVOY ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Enrichment Culture ◽  
Field Studies ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Adaxial Side ◽  
Abaxial Side ◽  
E Coli ◽  
Contaminated Irrigation Water

Numerous field studies have revealed that irrigation water can contaminate the surface of plants; however, the occurrence of pathogen internalization is unclear. This study was conducted to determine the sites of Escherichia coli O157:H7 contamination and its survival when the bacteria were applied through spray irrigation water to either field-grown spinach or lettuce. To differentiate internalized and surface populations, leaves were treated with a surface disinfectant wash before the tissue was ground for analysis of E. coli O157:H7 by direct plate count or enrichment culture. Irrigation water containing E. coli O157:H7 at 102, 104, or 106 CFU/ml was applied to spinach 48 and 69 days after transplantation of seedlings into fields. E. coli O157:H7 was initially detected after application on the surface of plants dosed at 104 CFU/ml (4 of 20 samples) and both on the surface (17 of 20 samples) and internally (5 of 20 samples) of plants dosed at 106 CFU/ml. Seven days postspraying, all spinach leaves tested negative for surface or internal contamination. In a subsequent study, irrigation water containing E. coli O157:H7 at 108 CFU/ml was sprayed onto either the abaxial (lower) or adaxial (upper) side of leaves of field-grown lettuce under sunny or shaded conditions. E. coli O157:H7 was detectable on the leaf surface 27 days postspraying, but survival was higher on leaves sprayed on the abaxial side than on leaves sprayed on the adaxial side. Internalization of E. coli O157:H7 into lettuce leaves also occurred with greater persistence in leaves sprayed on the abaxial side (up to 14 days) than in leaves sprayed on the adaxial side (2 days).

Infrequent Internalization of Escherichia coli O157:H7 into Field-Grown Leafy Greens

2010 ◽  
Vol 73 (3) ◽  
pp. 500-506 ◽  
Author(s):  
MARILYN C. ERICKSON ◽  
CATHY C. WEBB ◽  
JUAN CARLOS DIAZ-PEREZ ◽  
SHARAD C. PHATAK ◽  
JOHN J. SILVOY ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Field Studies ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Leafy Greens ◽  
Contaminated Irrigation Water ◽  
Green Fluorescent ◽  
Field Plots ◽  
Spinach Leaves

Several sources of contamination of fresh produce by Escherichia coli O157:H7 (O157) have been identified and include contaminated irrigation water and improperly composted animal waste; however, field studies evaluating the potential for internalization of O157 into leafy greens from these sources have not been conducted. Irrigation water inoculated with green fluorescent plasmid–labeled Shiga toxin–negative strains (50 ml of 102, 104, or 106 CFU of O157 per ml) was applied to soil at the base of spinach plants of different maturities in one field trial. In a second trial, contaminated compost (1.8 kg of 103 or 105 CFU of O157 per g) was applied to field plots (0.25 by 3.0 m) prior to transplantation of spinach, lettuce, or parsley plants. E. coli O157:H7 persisted in the soil up to harvest (day 76 posttransplantation) following application of contaminated irrigation water; however, internalized O157 was not detected in any spinach leaves or in roots exposed to O157 during the early or late growing season. Internalized O157 was detected in root samples collected 7 days after plants were contaminated in mid-season, with 5 of 30 samples testing positive for O157 by enrichment; however, O157 was not detected by enrichment in surface-disinfected roots on days 14 or 22. Roots and leaves from transplanted spinach, lettuce, and parsley did not internalize O157 for up to 50 days in the second trial. These results indicate that internalization of O157 via plant roots in the field is rare and when it does occur, O157 does not persist 7 days later.

Lack of Internalization of Escherichia coli O157:H7 in Lettuce (Lactuca sativa L.) after Leaf Surface and Soil Inoculation

2009 ◽  
Vol 72 (10) ◽  
pp. 2028-2037 ◽  
Author(s):  
GUODONG ZHANG ◽  
LI MA ◽  
LARRY R. BEUCHAT ◽  
MARILYN C. ERICKSON ◽  
VANESSA H. PHELAN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Leaf Surface ◽  
Escherichia Coli O157 ◽  
Adaxial Side ◽  
Abaxial Side ◽  
E Coli ◽  
Lactuca Sativa L ◽  
Leaf Surfaces ◽  
Leaves And Roots ◽  
Leaf Lettuce

Survival and internalization characteristics of Escherichia coli O157:H7 in iceberg, romaine, and leaf lettuce after inoculation of leaf surfaces and soil were determined. A five-strain mixture of E. coli O157:H7 in water and cow manure extract was used as an inoculum for abaxial and adaxial sides of leaves at populations of 6 to 7 log and 4 log CFU per plant. The five strains were individually inoculated into soil at populations of 3 and 6 log CFU/g. Soil, leaves, and roots were analyzed for the presence and population of E. coli O157:H7. Ten (4.7%) of 212 samples of leaves inoculated on the adaxial side were positive for E. coli O157:H7, whereas 38 (17.9%) of 212 samples inoculated on the abaxial side were positive. E. coli O157:H7 survived for at least 25 days on leaf surfaces, with survival greater on the abaxial side of the leaves than on the adaxial side. All 212 rhizosphere samples and 424 surface-sanitized leaf and root samples from plants with inoculated leaves were negative for E. coli O157:H7, regardless of plant age at the time of inoculation or the location on the leaf receiving the inoculum. The pathogen survived in soil for at least 60 days. Five hundred ninety-eight (99.7%) of 600 surface-sanitized leaf and root samples from plants grown in inoculated soil were negative for E. coli O157:H7. Internalization of E. coli O157:H7 in lettuce leaves and roots did not occur, regardless of the type of lettuce, age of plants, or strain of E. coli O157:H7.

Persistence of Enterohemorrhagic Escherichia coli O157:H7 in Soil and on Leaf Lettuce and Parsley Grown in Fields Treated with Contaminated Manure Composts or Irrigation Water

2004 ◽  
Vol 67 (7) ◽  
pp. 1365-1370 ◽  
Author(s):  
MAHBUB ISLAM ◽  
MICHAEL P. DOYLE ◽  
SHARAD C. PHATAK ◽  
PATRICIA MILLNER ◽  
XIUPING JIANG
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Poultry Manure ◽  
Dairy Manure ◽  
Enterohemorrhagic Escherichia Coli ◽  
Avirulent Strain ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Manure Compost ◽  
Contaminated Irrigation Water

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 infections associated with lettuce and other leaf crops have occurred with increasing frequency in recent years. Contaminated manure and polluted irrigation water are probable vehicles for the pathogen in many outbreaks. In this study, the occurrence and persistence of E. coli O157:H7 in soil fertilized with contaminated poultry or bovine manure composts or treated with contaminated irrigation water and on lettuce and parsley grown on these soils under natural environmental conditions was determined. Twenty-five plots, each 1.8 by 4.6 m, were used for each crop, with five treatments (one without compost, three with each of the three composts, and one without compost but treated with contaminated water) and five replication plots for each treatment. Three different types of compost, PM-5 (poultry manure compost), 338 (dairy manure compost), and NVIRO-4 (alkaline-stabilized dairy manure compost), and irrigation water were inoculated with an avirulent strain of E. coli O157:H7. Pathogen concentrations were 107 CFU/g of compost and 105 CFU/ml of water. Contaminated compost was applied to soil in the field as a strip at 4.5 metric tons per hectare on the day before lettuce and parsley seedlings were transplanted in late October 2002. Contaminated irrigation water was applied only once on the plants as a treatment in five plots for each crop at the rate of 2 liters per plot 3 weeks after the seedlings were transplanted. E. coli O157:H7 persisted for 154 to 217 days in soils amended with contaminated composts and was detected on lettuce and parsley for up to 77 and 177 days, respectively, after seedlings were planted. Very little difference was observed in E. coli O157:H7 persistence based on compost type alone. E. coli O157:H7 persisted longer (by >60 days) in soil covered with parsley plants than in soil from lettuce plots, which were bare after lettuce was harvested. In all cases, E. coli O157:H7 in soil, regardless of source or crop type, persisted for >5 months after application of contaminated compost or irrigation water.

Disposition of Salmonella and Escherichia coli O157:H7 following Spraying of Contaminated Water on Cucumber Fruit and Flowers in the Field

2018 ◽  
Vol 81 (12) ◽  
pp. 2074-2081 ◽  
Author(s):  
MARILYN C. ERICKSON ◽  
JYE-YIN LIAO ◽  
ALISON S. PAYTON ◽  
PETER W. COOK ◽  
JESUS BAUTISTA ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Enrichment Culture ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Cucumber Fruit ◽  
Pathogen Prevalence ◽  
Subsequent Exposure ◽  
Foodborne Outbreaks ◽  
Contaminated Irrigation Water

ABSTRACT Cucumbers are frequently consumed raw and have been implicated in several recent foodborne outbreaks. Because this item may become contaminated at the farm, it is vital to explore the fate of attenuated Salmonella Typhimurium or Escherichia coli O157:H7 sprayed onto foliage, flowers, and fruit in fields and determine whether pre- or postcontamination spray interventions could minimize contamination. After spraying cucumber plants with contaminated irrigation water (3.8 log CFU/mL of Salmonella Typhimurium and E. coli O157:H7), 60 to 78% of cucumber fruit were not contaminated because the plant's canopy likely prevented many of the underlying fruit from being exposed to the water. Subsequent exposure of contaminated cucumber plants to a simulated shower event did not appear to dislodge pathogens from contaminated foliage onto the fruit, nor did it appear to consistently wash either pathogen from the fruit. Spraying flowers and attached ovaries directly with a pathogen inoculum (4.6 log CFU/mL) initially led to 100% and 65 to 90% contamination, respectively. Within 3 days, 30 to 40% of the flowers were still contaminated; however, contamination of ovaries was minimal (≤10%), suggesting it was unlikely that internalization occurred through the flower to the ovary with these pathogen strains. In another study, both pathogens were found on a withered flower but not on the fruit to which the flower was attached, suggesting that this contaminated flower could serve as a source of cross-contamination in a storage bin if harvested with the fruit. Because pre- and postcontamination acetic acid–based spray treatments failed to reduce pathogen prevalence, the probability that fruit initially contaminated at 1.3 to 2.8 log CFU of Salmonella Typhimurium or E. coli O157:H7 per cucumber would be positive by enrichment culture decreased by a factor of 1.6 and 1.9 for Salmonella Typhimurium and E. coli O157:H7, respectively, for every day the fruit was held in the field (P ≤ 0.0001). Hence, to reduce the prevalence of Salmonella Typhimurium on cucumbers below 5%, more than 1 week would be required.

Bioluminescence: A Rapid Indicator of Escherichia Coli O157:H7 in Selected Yogurt and Cheese Varieties

1997 ◽  
Vol 60 (8) ◽  
pp. 891-897 ◽  
Author(s):  
L. M. HUDSON ◽  
J. CHEN ◽  
A. R. HILL ◽  
M. W. GRIFFITHS
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Cottage Cheese ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Potential Hazard ◽  
Growth And Survival ◽  
E Coli ◽  
Standard Plate Count ◽  
Standard Plate

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 have been commonly associated with products derived from ground beef, but recently the organism has been implicated as the causative agent in outbreaks involving yogurt and cheese. This finding has raised concern about the potential for its growth and survival in fermented dairy products. A bioluminescent strain of E. coli O157:H7 was used to determine postprocessing survival in yogurt with live cultures at pH 4.17, 4.39, and 4.47 stored at 4 and 10°C. In addition, survival of E. coli O157:H7 was monitored during the manufacture of Cottage, Colby, Romano, and Feta cheeses. Results indicated survival for 8 and 5 days at 4 and 10°C respectively in yogurt at pH 4.17, 17 and 15 days at 4 and 10°C respectively in yogurt at pH 4.39, and 17days at both 4 and 10°C in yogurt at pH 4.47. E. coli O157:H7 did not survive cooking procedures at 56°C in Cottage cheese. However, the pathogen survived for 27, 30, and 27 days in Colby, Romano, and Feta cheeses respectively. A high correlation of r2 > 0.89 was obtained between counts of bioluminescenct colonies and standard plate count for all yogurt and cheese varieties, indicating that bioluminescence was a sensitive and rapid indicator of cellular viability for E. coli O157:H7. Survival of the pathogen, as indicated by this method, is possible in highly acidic environments even at refrigeration temperatures. This poses a potential hazard should postprocessing contamination occur.

Survival of Escherichia coli O157:H7 in Ground-Beef Patties during Storage at 2, −2, 15 and then −2°C, and −20°C†

1999 ◽  
Vol 62 (11) ◽  
pp. 1243-1247 ◽  
Author(s):  
SUSAN E. ANSAY ◽  
KIM A. DARLING ◽  
CHARLES W. KASPAR
Keyword(s):  
Escherichia Coli ◽  
Frozen Storage ◽  
Ground Beef ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Control Strain ◽  
Single Strain ◽  
E Coli ◽  
Beef Patties ◽  
Significant Difference

The survival of Escherichia coli O157:H7 and of a nonpathogenic control strain of E. coli was monitored in raw ground beef that was stored at 2°C for 4 weeks, −2°C for 4 weeks, 15°C for 4 h and then −2°C for 4 weeks, and −20°C. Irradiated ground beef was inoculated with one E. coli control strain or with a four-strain cocktail of E. coli O157:H7 (ca. 105 CFU/g), formed into patties (30 to 45 g), and stored at the appropriate temperature. The numbers of the E. coli control strain decreased by 1.4 log10 CFU/g, and pathogen numbers declined 1.9 log10 CFU/g when patties were stored for 4 weeks at 2°C. When patties were stored at −2°C for 4 weeks, the numbers of the E. coli control strain and the serotype O157:H7 strains decreased 2.8 and 1.5 log10 CFU/g, respectively. Patties stored at 15°C for 4 h prior to storage at −2°C for 4 weeks resulted in 1.6 and 2.7 log10–CFU/g reduction in the numbers of E. coli and E. coli O157:H7, respectively. Storage of retail ground beef at 15°C for 4 h (tempering) did not result in increased numbers of colony forming units per gram, as determined with violet red bile, MRS lactobacilli, and plate-count agars. Frozen storage (−20°C) of ground-beef patties that had been inoculated with a single strain of E. coli resulted in approximately a 1 to 2 log10–CFU/g reduction in the numbers of the control strain and individual serotype O157:H7 strains after 1 year. There was no significant difference between the survival of the control strain and the O157:H7 strains, nor was there a difference between O157:H7 strains. These data demonstrate that tempering of ground-beef patties prior to low-temperature storage accelerated the decline in the numbers of E. coli O157:H7.

Effects of Oxidative Compounds on Thermotolerance in Escherichia coli O157:H7 Strains EO139 and 380-94

2005 ◽  
Vol 68 (11) ◽  
pp. 2443-2446 ◽  
Author(s):  
ISABEL C. BLACKMAN ◽  
YOUNG W. PARK ◽  
MARK A. HARRISON
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Ascorbic Acid ◽  
Lethal Effect ◽  
Iron Chloride ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Bacterial Cells ◽  
E Coli ◽  
Chloride Hexahydrate

An oxidative complex composed of ferric iron chloride hexahydrate, ADP, and ascorbic acid can generate hydrogen peroxide and hydroxyl radicals in fibroblasts. These compounds are naturally found in meat and meat-based products and may elicit oxidative stress on Escherichia coli O157:H7, thus conferring thermotolerance to the bacterium due to the phenomenon of the global stress response. The effect of the levels of the oxidative complex on the thermotolerance of E. coli O157:H7 was investigated. Cultures of E. coli O157:H7 strains EO139 and 380-94 were mixed in three different concentrations (10:10: 40, 15:15:60, and 20:20:80 μM) of the oxidative complex (iron III chloride, ADP, and ascorbic acid, respectively). The samples were inserted into capillary tubes and heated in a circulating water bath at 59 and 60°C for EO139 and 380-94, respectively. Tubes were removed at intervals of 5 min for up to 1 h and contents spirally plated on plate count agar that was incubated for 48 h at 37°C. The thermotolerance of both E. coli O157:H7 strains EO139 and 380-94 was influenced by the concentrations of the oxidative complex. The ratio of 10:10:40 μM enhanced thermotolerance of EO139 and 390-94 at 59 and 60°C, respectively. However, exposure to the ratios of 15:15:60 and 20:20:80 μM rendered the pathogen more sensitive to the lethal effect and did not enhance the thermotolerance of the cells. The significance of this study is twofold. This experiment proves that oxidative stress can enhance thermotolerance of bacterial cells induced by an oxidative complex if only in a specific ratio and concentration. It is possible to speculate that if the chemical compounds are present in this ratio in meats, they may enhance the thermal resistance of E. coli O157:H7 and make the bacteria more difficult to eliminate, thus increasing the risk of foodborne illness in consumers.

Fate of Escherichia coli O157:H7 during Composting of Bovine Manure in a Laboratory-Scale Bioreactor

2003 ◽  
Vol 66 (1) ◽  
pp. 25-30 ◽  
Author(s):  
XIUPING JIANG ◽  
JENNIE MORGAN ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Moisture Content ◽  
Enrichment Culture ◽  
Escherichia Coli O157 ◽  
External Temperature ◽  
E Coli ◽  
Self Heating ◽  
Large Populations ◽  
Constant Moisture Content ◽  
Carbon Nitrogen Ratio

Inactivation profiles of Escherichia coli O157:H7 in inoculated bovine manure–based compost ingredients were determined by composting these ingredients in a bioreactor under controlled conditions. A 15-liter bioreactor was constructed to determine the fate of E. coli O157:H7 and changes in pH, moisture content, temperature, and aerobic mesophilic and thermophilic bacterial counts during composting. Fresh cow manure, wheat straw, cottonseed meal, and ammonium sulfate were combined to obtain a moisture content of ca. 60% and a carbon/nitrogen ratio of 29:1. The compost ingredients were held in the bioreactor at a constant external temperature of 21 or 50°C. Self-heating of the ingredients due to microbial activity occurred during composting, with stratified temperatures occurring within the bioreactor. At an external temperature of 21°C, self-heating occurred for 0 to 3 days, depending on the location within the bioreactor. E. coli O157:H7 populations increased by 1 to 2 log10 CFU/g during the initial 24 h of composting and decreased by ca. 3.5 log10 CFU/g near the bottom of the bioreactor and by ca. 2 log10 CFU/g near the middle and at the top during 36 days of composting. At an external temperature of 50°C, E. coli O157:H7 was inactivated rapidly (by ca. 4.9 log10 CFU/g at the top of the bioreactor, by 4.0 log10 CFU/g near the middle, and by 5.9 log10 CFU/g near the bottom) within 24 h of composting. When inoculated at an initial level of ca. 107 CFU/g, E. coli O157:H7 survived for 7 days but not for 14 days at all three sampling locations, as indicated by either direct plating or enrichment culture. At the top of the bioreactor a relatively constant moisture content of 60% was maintained, whereas the moisture content near the bottom decreased steadily to 37 to 45% over 14 days of composting. The pH of the composting mixture decreased to ca. 6 within 1 to 3 days and subsequently increased to 8 to 9. Results obtained in this study indicate that large populations (104 to 107 CFU/g) of E. coli O157:H7 survived for 36 days during composting in a bioreactor at an external temperature of 21°C but were inactivated to undetectable levels after 7 to 14 days when the external temperature of the bioreactor was 50°C. Hence, manure contaminated with large populations (e.g., 107 CFU/g) of E. coli O157:H7 should be composted for more than 1 week, and preferably for 2 weeks, when held at a minimum temperature of 50°C.

scholarly journals Prevalence and antibiotic resistance profile of Shiga-toxigenic Escherichia coli O157 (STEC) from retailed miscellaneous meat and fish types in Abuja, Nigeria

2021 ◽  
Vol 2 (2) ◽  
pp. 37-43
Author(s):  
Adaeze Joy Alu ◽  
Gabriel K. Omeiza ◽  
James A. Ameh ◽  
Enem S.I
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Enrichment Culture ◽  
Intestinal Bacteria ◽  
Latex Agglutination ◽  
Multi Drug Resistance ◽  
Escherichia Coli O157 ◽  
Resistance Profile ◽  
E Coli ◽  
Antibiotic Resistance Profile

Most Escherichia coli strains are harmless intestinal bacteria of animals, but some are implicated in food infection/poisoning especially Shiga toxin (or Vero toxin) producing E. coli (STEC) due to consumption of meat. This study was conducted to determine the prevalence and antibiotic resistance profile of Shigatoxigenic Escherichia coli O157 (STEC) from retailed miscellaneous fish and meat types in Abuja, Federal Capital Territory, Nigeria. A total of 256 meat and fish consisting of cow muscles, intestines, rumen-sacs, livers and tails, cat-fish, frozen fish (mackerel and herrings) were examined. Escherichia coli were isolated by enrichment culture cefixime-tellurite sorbitol MacConkey agar (CT-SMAC), morphological, biochemical, serotype latex agglutination and disk diffusion methods. Of the 256 samples, 138 (53.9%) were contaminated with E. coli and 28 (21.7%) E. coli strains were positive for Shigatoxigenic Escherichia coli O157 (STEC). Meat muscles had the highest prevalence of STEC (7.41%) among meat samples, followed by rumen-sacs (6.0%), intestines (5.77%), tails (4.0%), and the prevalence of STEC in Fish includes Cat-fish intestine (26.7%), skin (21.4%), Mackerel intestine (26.7%), skin (14.3%), and Herrings skin (15.4%), gill (7.1%). All the STEC assessed indicated multi-drug resistance, with the isolates showing 100% resistant to ampicilin, and erythromycin, nitrofurantoin (95.7%), amoxicilin clavulanic acid (84.3%), sulphamethaxazole/trimethoprim (75%), streptomycin (75%), tetracycline (66.17%), and gentamycin (53.6%). The isolates were susceptible to ciprofloxacin (66.7%), Cefoxitin (66.7%), amikacin (39.3%), and chloramphenicol (35.7%). The implication of STEC in this study suggests that contaminated meat types are sold to consumers and can result to serious foodborne hazards. Prescription of ciprofloxacin and cefoxicilin are recommended against this organism. Application of good hygienic procedures in meat and fish handling processes and proper boiling before consumption can mitigate the risk of infection due to resistance STEC strains.

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