Inhibition of Growth of Escherichia coli O157:H7 in Fresh Radish (Raphanus sativus L.) Sprout Production by Calcinated Calcium

1999 ◽  
Vol 62 (2) ◽  
pp. 128-132 ◽  
Author(s):  
M. L. BARI ◽  
H. KUSUNOKI ◽  
H. FURUKAWA ◽  
H. IKEDA ◽  
K. ISSHIKI ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Raphanus Sativus ◽  
Inhibitory Effect ◽  
Seed Extract ◽  
Escherichia Coli O157 ◽  
Experimental Conditions ◽  
E Coli ◽  
Inhibition Of Growth ◽  
Raphanus Sativus L ◽  
Radish Sprouts

The inhibitory effect of calcinated calcium on the growth of Escherichia coli O157:H7 during fresh radish (Raphanus sativus L.) sprout production was studied. It was revealed that the addition of 0.4% (wt/vol) calcinated calcium into radish sprouting medium which was artificially contaminated with E. coli O157:H7 (3.0 to 3.2 log CFU/ml) completely inhibited the growth or inactivated the microorganism. When radish seed extract was used instead of radish sprout production, the same extent of growth inhibition or inactivation was observed with much lower amounts (0.07%) of calcinated calcium under similar experimental conditions. The findings suggested that calcinated calcium may be useful to control E. coli O157:H7 contamination during the production of radish sprouts.

Simultaneous Enrichment of Shiga Toxin–Producing Escherichia coli O157 and O26 and Salmonella in Food Samples Using Universal Preenrichment Broth

2009 ◽  
Vol 72 (10) ◽  
pp. 2065-2070 ◽  
Author(s):  
MASASHI KANKI ◽  
KAZUKO SETO ◽  
JUNKO SAKATA ◽  
TETSUYA HARADA ◽  
YUKO KUMEDA
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Food Samples ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Significant Difference ◽  
Peptone Water ◽  
Radish Sprouts ◽  
Pork Samples ◽  
Better Than

Universal preenrichment broth (UPB) was compared with modified Escherichia coli broth with novobiocin (mEC+n) for enrichment of Shiga toxin–producing E. coli O157 and O26, and with buffered peptone water (BPW) for preenrichment of Salmonella enterica. Ten strains each of the three pathogens were inoculated into beef and radish sprouts following thermal, freezing, or no treatment. With regard to O157 and O26, UPB incubated at 42°C recovered significantly more cells from inoculated beef than UPB at 35°C and from radish sprout samples than UPB at 35°C and mEC+n. With regard to Salmonella, UPB incubated at 42°C was as effective as UPB at 35°C and BPW at recovering cells from beef and radish sprout samples. No significant difference was noted between the effectiveness of UPB at 42°C and UPB at 35°C or BPW in the recovery of Salmonella from 205 naturally contaminated poultry samples. By using UPB at 42°C, one O157:H7 strain was isolated from the mixed offal of 53 beef samples, 6 cattle offal samples, and 50 pork samples all contaminated naturally, with no pathogen inoculation. The present study found that UPB incubated at 42°C was as effective as, or better than, mEC+n for enrichment of O157 and O26 and comparable to BPW for preenrichment of Salmonella. These findings suggest that a great deal of labor, time, samples, and space may be saved if O157, O26, and Salmonella are enriched simultaneously with UPB at 42°C.

Viability of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Yellow Fat Spreads as Affected by Storage Temperature

2003 ◽  
Vol 66 (4) ◽  
pp. 549-558 ◽  
Author(s):  
SARAH L. HOLLIDAY ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Storage Temperature ◽  
Salt Content ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Inhibition Of Growth ◽  
Time Required ◽  
Kinetics Of

A study was conducted to characterize the survival and inactivation kinetics of a five-serotype mixture of Salmonella (6.23 to 6.55 log10 CFU per 3.5-ml or 4-g sample), a five-strain mixture of Escherichia coli O157:H7 (5.36 to 6.14 log10 CFU per 3.5-ml or 4-g sample), and a six-strain mixture of Listeria monocytogenes (5.91 to 6.18 log10 CFU per 3.5-ml or 4-g sample) inoculated into seven yellow fat spreads (one margarine, one butter-margarine blend, and five dairy and nondairy spreads and toppings) after formulation and processing and stored at 4.4, 10, and 21°C for up to 94 days. Neither Salmonella nor E. coli O157:H7 grew in any of the test products. The time required for the elimination of each pathogen depended on the product and the storage temperature. Death was more rapid at 21°C than at 4.4 or 10°C. Depending on the product, the time required for the elimination of viable cells at 21°C ranged from 5 to 7 days to >94 days for Salmonella, from 3 to 5 days to 28 to 42 days for E. coli O157:H7, and from 10 to 14 days to >94 days for L. monocytogenes. Death was most rapid in a water-continuous spray product (pH 3.66, 4.12% salt) and least rapid in a butter-margarine blend (pH 6.66, 1.88% salt). E. coli O157:H7 died more rapidly than did Salmonella or L. monocytogenes regardless of storage temperature. Salmonella survived longer in high-fat (≥61%) products than in products with lower fat contents. The inhibition of growth is attributed to factors such as acidic pH, salt content, the presence of preservatives, emulsion characteristics, and nutrient deprivation. L. monocytogenes did not grow in six of the test products, but its population increased between 42 and 63 days in a butter-margarine blend stored at 10°C and between 3 and 7 days when the blend was stored at 21°C. On the basis of the experimental parameters examined in this study, traditional margarine and spreads not containing butter are not “potentially hazardous foods” in that they do not support the growth of Salmonella, E. coli O157:H7, or L. monocytogenes.

In Vitro Inactivation of Escherichia coli O157:H7 in Bovine Rumen Fluid by Caprylic Acid

2004 ◽  
Vol 67 (5) ◽  
pp. 884-888 ◽  
Author(s):  
THIRUNAVUKKARASU ANNAMALAI ◽  
MANOJ KUMAR MOHAN NAIR ◽  
PATRICK MAREK ◽  
PRADEEP VASUDEVAN ◽  
DAVID SCHREIBER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Caprylic Acid ◽  
Rumen Fluid ◽  
Bacterial Load ◽  
Anaerobic Bacteria ◽  
Inhibitory Effect ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Bovine Rumen

The antibacterial effect of caprylic acid (35 and 50 mM) on Escherichia coli O157:H7 and total anaerobic bacteria at 39° C in rumen fluid (pH 5.6 and 6.8) from 12 beef cattle was investigated. The treatments containing caprylic acid at both pHs significantly reduced (P < 0.05) the population of E. coli O157:H7 compared with that in the control samples. At pH 5.6, both levels of caprylic acid killed E. coli O157:H7 rapidly, reducing the pathogen population to undetectable levels at 1 min of incubation (a more than 6.0-log CFU/ml reduction). In buffered rumen fluid at pH 6.8, 50 mM caprylic acid reduced the E. coli O157:H7 population to undetectable levels at 1 min of incubation, whereas 35 mM caprylic acid reduced the pathogen by approximately 3.0 and 5.0 log CFU/ml at 8 and 24 h of incubation, respectively. At both pHs, caprylic acid had a significantly lesser (P < 0.05) and minimal inhibitory effect on the population of total anaerobic bacteria in rumen compared with that on E. coli O157:H7. At 24 h of incubation, caprylic acid (35 and 50 mM) reduced the population of total anaerobic bacteria by approximately 2.0 log CFU/ml at pH 5.6, whereas at pH 6.8, caprylic acid (35 mM) did not have any significant (P > 0.05) inhibitory effect on total bacterial load. Results of this study revealed that caprylic acid was effective in inactivating E. coli O157:H7 in bovine rumen fluid, thereby justifying its potential as a preslaughter dietary supplement for reducing pathogen carriage in cattle.

Potential Hazard of Radish Sprouts as a Vehicle of Escherichia coli O157:H7

1997 ◽  
Vol 60 (9) ◽  
pp. 1125-1127 ◽  
Author(s):  
Y. HARA-KUDO ◽  
H. KONUMA ◽  
M. IWAKI ◽  
F. KASUGA ◽  
Y. SUGITA-KONISHI ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Potential Hazard ◽  
E Coli ◽  
Radish Sprouts ◽  
Edible Parts

We studied the contamination of radish sprouts after exposure to Escherichia coli O157:H7-inoculated water in the laboratory. The edible parts, the cotyledons and hypocotyl, became heavily contaminated with E. coli O157:H7 when they were grown from seeds soaked in E. coli O157:H7-inoculated water. These same parts became contaminated with E. coli O157:H7 when their roots were dipped into E. coli O157:H7-inoculated water. These findings suggest that E. coli O157:H7 contamination in the edible parts of radish sprouts could pose a serious hazard if the seeds or hydroponic water are contaminated with the bacterium.

Enhanced Inhibition of Escherichia coli O157:H7 by Lysozyme and Chelators

2003 ◽  
Vol 66 (10) ◽  
pp. 1783-1789 ◽  
Author(s):  
J. S. BOLAND ◽  
P. M. DAVIDSON ◽  
J. WEISS
Keyword(s):  
Escherichia Coli ◽  
Inhibitory Activity ◽  
Chelating Agents ◽  
Inhibitory Effect ◽  
Escherichia Coli O157 ◽  
Inhibitory Effects ◽  
Antimicrobial Spectrum ◽  
E Coli ◽  
Dilution Assay ◽  
Microbroth Dilution

This study examined the effects of three chelating agents (EDTA, disodium pyrophosphate [DSPP], and pentasodium tripolyphosphate [PSTPP]) on the inhibition of the growth of Escherichia coli O157:H7 by lysozyme. The objective of this study was to identify replacement chelators that exhibit synergistic properties similar to those of EDTA. The inhibitory effects of EDTA at 300 to 1,500 μg/ml and of DSPP and PSTPP at 3,000 to 15,000 μg/ml in combination with lysozyme at 200 to 600 μg/ml for up to 48 h at pHs of 6.0, 7.0, and 8.0 on four strains of E. coli O157:H7 was studied with the use of a microbroth dilution assay. The addition of EDTA enhanced lysozyme's inhibitory effect on strains of E. coli O157:H7. EDTA at ≥300 μg/ml combined with lysozyme at 200 to 600 μg/ml was sufficient to inhibit the growth of the strains at pHs of 6.0 and 8.0. At pH 7.0, lysozyme at 200 to 600 μg/ml and EDTA concentrations of ≥1,000 μg/ml were effective in inhibiting three of the four strains. DSPP at pH 6.0 was inhibitory at ≥10,000 μg/ml when combined with lysozyme at 200 to 300 μg/ml. In contrast, PSTPP increased the inhibitory activity of lysozyme more effectively at pH 8.0. Lysozyme at 200 to 600 μg/ml was effective against two strains of E. coli O157:H7 when used in conjunction with PSTPP at ≥5,000 μg/ml. The remaining strains were inhibited by PSTPP at ≥10,000 μg/ml. Our results indicate that inhibition occurred with each lysozyme-chelator combination, but the concentrations of phosphates required to increase the antimicrobial spectrum of lysozyme against E. coli O157:H7 were higher than the EDTA concentrations required to achieve the same effect.

Association of Escherichia coli O157:H7 with Filth Flies (Muscidae and Calliphoridae) Captured in Leafy Greens Fields and Experimental Transmission of E. coli O157:H7 to Spinach Leaves by House Flies (Diptera: Muscidae)

2009 ◽  
Vol 72 (7) ◽  
pp. 1547-1552 ◽  
Author(s):  
J. L. TALLEY ◽  
A. C. WAYADANDE ◽  
L. P. WASALA ◽  
A. C. GERRY ◽  
J. FLETCHER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Fluorescent Protein ◽  
Pcr Amplification ◽  
Escherichia Coli O157 ◽  
Experimental Conditions ◽  
House Flies ◽  
E Coli ◽  
Leafy Greens ◽  
Filth Flies

The recent outbreak of Escherichia coli O157:H7 infection associated with contaminated spinach led to an investigation of the role of insects, which frequent fields of leafy greens and neighboring rangeland habitats, in produce contamination. Four leafy greens fields adjacent to cattle-occupied rangeland habitats were sampled using sweep nets and sticky traps. Agromyzid flies, anthomyiid flies, and leafhoppers were caught consistently in both rangeland and leafy greens production fields at all sites. An unexpected number of flies (n = 34) in the Muscidae and Calliphoridae families (known as filth flies because of their development in animal feces) were caught in one leafy greens field. A subset of these filth flies were positive (11 of 18 flies) for E. coli O157:H7 by PCR amplification using primers for the E. coli O157:H7–specific eae gene. Under laboratory conditions, house flies were confined on manure or agar medium containing E. coli O157:H7 tagged with green fluorescent protein (GFP) and then tested for their capacity to transfer the microbes to spinach plants. GFP-tagged bacteria were detected on surfaces of 50 to 100% of leaves examined by fluorescence microscopy and in 100% of samples tested by PCR. These results indicate that flies are capable of contaminating leafy greens under experimental conditions and confirm the importance of further investigation of the role of insects in contamination of fresh produce.

Role of Nutrient Limitation in the Competition between Pseudomonas fluorescens and Escherichia coli O157:H7

2007 ◽  
Vol 70 (7) ◽  
pp. 1739-1743 ◽  
Author(s):  
R. C. MCKELLAR
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Fluorescens ◽  
Nutrient Limitation ◽  
Foodborne Pathogens ◽  
Raw Milk ◽  
Inhibitory Effect ◽  
Nutrient Broth ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Spoilage Microflora

Competition between spoilage microorganisms and foodborne pathogens provides a potentially simple approach to limiting the growth of pathogens. A strain of Pseudomonas fluorescens isolated from raw milk repressed growth of Escherichia coli O157:H7 at 22°C in nutrient broth once the maximum population density of the pseudomonad had been reached (9.6 log CFU ml−1). The presence of iron in the growth medium and the parallel inhibitory effect of a siderophore-deficient mutant of P. fluorescens precluded iron limitation as the mechanism of action. Medium depleted by prior growth of P. fluorescens prevented the growth of E. coli, and this effect was reversed by the replenishment of the nutrient broth, its component fractions, or the addition of soy peptones but not peptones derived from milk protein. This is the first report of competition between spoilage microflora and foodborne pathogens in which the mechanism was clearly shown to be nutrient limitation. These results suggest possible improvements in biocontrol systems to prevent pathogen growth on foods.

scholarly journals Enterohemorrhagic Escherichia coli O157:H7 Present in Radish Sprouts

1998 ◽  
Vol 64 (4) ◽  
pp. 1532-1535 ◽  
Author(s):  
Yoshinori Itoh ◽  
Yoshiko Sugita-Konishi ◽  
Fumiko Kasuga ◽  
Masaaki Iwaki ◽  
Yukiko Hara-Kudo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Scanning Electron Microscopy ◽  
Outer Surface ◽  
Immunofluorescence Microscopy ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Radish Sprouts ◽  
Scanning Electron

ABSTRACT Using cultivation, immunofluorescence microscopy, and scanning electron microscopy, we demonstrated the presence of viable enterohemorrhagic Escherichia coli O157:H7 not only on the outer surfaces but also in the inner tissues and stomata of cotyledons of radish sprouts grown from seeds experimentally contaminated with the bacterium. HgCl2 treatment of the outer surface of the hypocotyl did not kill the contaminating bacteria, which emphasized the importance of either using seeds free from E. coli O157:H7 in the production of radish sprouts or heating the sprouts before they are eaten.

Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes by PR-26, a Synthetic Antibacterial Peptide†

2001 ◽  
Vol 64 (12) ◽  
pp. 1929-1934 ◽  
Author(s):  
THIRUNAVUKKARASU ANNAMALAI ◽  
KUMAR S. VENKITANARAYANAN ◽  
THOMAS A. HOAGLAND ◽  
MAZHAR I. KHAN
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Antibacterial Effect ◽  
Inhibitory Effect ◽  
Final Concentration ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Complete Inactivation ◽  
Peptone Water ◽  
Water Ph

This study reports the antibacterial effect of PR-26, a synthetic peptide derived from the first 26 amino acid sequence of PR-39, an antimicrobial peptide isolated from porcine neutrophils. A three-strain mixture of Escherichia coli O157:H7 or Listeria monocytogenes of approximately 108 CFU was inoculated to a final concentration of 107 CFU/ml in 1% peptone water (pH 7.0), containing 50 or 75 μg/ml of PR-26, and incubated at 37°C for 0, 6, 12, and 24 h; at 24°C for 0, 12, 24, and 36 h; or at 10 or 4°C for 0, 24, 72, and 120 h. Control samples included 1% peptone water inoculated with each pathogen mixture but containing no PR-26. The surviving population of each pathogen at each sampling time was determined by plating on tryptic soy agar with incubation at 37°C for 24 h. At 37°C, PR-26 decreased E. coli O157:H7 and L. monocytogenes populations by >5.0 log CFU/ml at 12 h, with complete inactivation at 24 h. At 24°C, PR-26 reduced E. coli O157:H7 and L. monocytogenes by approximately 3.5, 4.0, and 4.5 log CFU/ml at the end of 12-, 24-, and 36-h incubations, respectively. At 4 and 10°C, the inhibitory effect of PR-26 on E. coli O157:H7 and L. monocytogenes was significantly lower (P < 0.05) than that at 37 and 24°C; a 2- to 3-log CFU/ml reduction was observed at 120-h incubation. Results indicate that PR-26 could potentially be used as an antimicrobial agent, but applications in appropriate foods need to be validated.

scholarly journals An Improved Enrichment Broth for Isolation of Escherichia coli O157, with Specific Reference to Starved Cells, from Radish Sprouts

2003 ◽  
Vol 69 (3) ◽  
pp. 1858-1860 ◽  
Author(s):  
Shin Sata ◽  
Tomohiko Fujisawa ◽  
Ro Osawa ◽  
Atsushi Iguchi ◽  
Shiro Yamai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Specific Reference ◽  
Escherichia Coli O157 ◽  
Macconkey Agar ◽  
Enrichment Broth ◽  
E Coli ◽  
Peptone Water ◽  
Radish Sprouts

ABSTRACT An enrichment broth was developed for the efficient isolation of Escherichia coli O157 from radish sprouts. The broth was buffered peptone water containing 0.5% sodium thioglycolate (STG-BPW), which was designed to allow growth of E. coli O157 in starved and unstarved states. However, this medium suppressed the growth of non-carbohydrate-fermenting obligate aerobes whose colonial appearance on sorbitol MacConkey agar containing cefixime and tellurite (CT-SMAC) resembled that of E. coli O157. Both starved and unstarved cells of E. coli O157 experimentally inoculated into radish sprouts were successfully recovered with STG-BPW enrichment in all cases, most of which showed marked disappearance of E. coli O157-like colonies on CT-SMAC.

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