Determining Process Lethality of Escherichia Coli O157:H7 and Salmonella in Heat Treated, Rendered Oil

Escherichia coli serotype O157:H7 cells were grown at 30°C for 6 h and subjected to a heat stress, or heat shock, at 42°C for 5 min. Heat-shocked and nonheat-shocked controls were heat treated at 55°C for up to 60 min. The number of injured cells was significantly higher in heat-shocked cells than in controls, and the rate of release of cell components was higher in heat-shocked cells. Anaerobic plating resulted in higher recovery of injured cells, when compared with aerobic plating, regardless of whether the cells were heat shocked or not. In addition, heat shocking resulted in lower catalase and superoxide dismutase activities when compared with controls. It also resulted in greater survivability after exposure to hydrogen peroxide, suggesting that heat shocking somehow enables the cells to survive exposure to toxic substances in addition to heat. The heat-shock response, coupled with anaerobic conditions, increased the ability of E. coli O157:H7 cells to recover after a heat treatment. Thus, heat shock did not afford protection to the cells against injury, but rather enhanced their ability to recover during storage.

Download Full-text

Behavior of Hemorrhagic Escherichia coli O157:H7 During the Manufacture of Cottage Cheese

Journal of Food Protection ◽

10.4315/0362-028x-55.5.379 ◽

1992 ◽

Vol 55 (5) ◽

pp. 379-381 ◽

Cited By ~ 42

Author(s):

MARLENE M. AROCHA ◽

MELINDA MCVEY ◽

SUSAN D. LODER ◽

JOHN H. RUPNOW ◽

LLOYD BULLERMAN

Keyword(s):

Escherichia Coli ◽

Glucuronic Acid ◽

Skim Milk ◽

Enterohemorrhagic Escherichia Coli ◽

Cottage Cheese ◽

Escherichia Coli O157 ◽

Phenol Red ◽

E Coli ◽

Heat Treated ◽

And Control

The ability of enterohemorrhagic Escherichia coli O157:H7 to grow and survive during the manufacture of Cottage cheese was determined. Pasteurized skim milk artificially contaminated with E. coli O157:H7 was used to make Cottage cheese by the washed curd method. E. coli O157:H7 was enumerated by surface plating samples on MacConkey sorbitol agar with 5-bromo-4-chloro-3-indoxyl-β-D-glucuronic acid cyclohexylammonium salt (MSA-BCIG) and incubating at 42°C for 24 h. The heat treated samples were previously inoculated into a modified EC broth with novobiocin and incubated static at 35°C for 24 h. Sorbitol and β-glucuronidase negative colonies were picked from MSA-BCIG, spread on Levine eosin methylene blue agar plates and phenol red sorbitol agar plates with 4-methylumbelliferyl-β-D-glucuronide (PRS-MUG) added for confirmation. E. coli O157:H7 increased 100-fold in numbers during the manufacturing process, but death occurred during cooking of the curd and whey. The pH and acidity did not halt the growth of this pathogen during the manufacture of the cheese; furthermore, the values of these parameters were the same between the contaminated and control samples.

Download Full-text

Modulation of Wound-Induced Hydrogen Peroxide and Its Influence on the Fate of Escherichia coli O157:H7 in Cut Lettuce Tissues

Journal of Food Protection ◽

10.4315/0362-028x.jfp-12-208 ◽

2012 ◽

Vol 75 (12) ◽

pp. 2208-2212 ◽

Cited By ~ 4

Author(s):

PETER M. A. TOIVONEN ◽

CHANGWEN LU ◽

SUSAN BACH ◽

PASCAL DELAQUIS

Keyword(s):

Escherichia Coli ◽

Hydrogen Peroxide ◽

Response To Treatment ◽

Escherichia Coli O157 ◽

Romaine Lettuce ◽

Sodium Pyruvate ◽

E Coli ◽

Heat Treated ◽

Cutting Heat ◽

Microbial Analysis

Wounding of lettuce tissue has been examined previously by others in regard to browning reactions, and treatments to modulate wounding responses were evaluated for reduction of browning. However, the wounding process also releases oxygen radicals such as hydrogen peroxide. This study focused on the evaluation of two treatments that reduce hydrogen peroxide at cut surfaces (heat treatment and pyruvate addition) and one treatment that enhances its production (infusion with the fungal elicitor harpin). Hydrogen peroxide changes in response to treatment were also associated with resultant survival of Escherichia coli O157:H7, which was inoculated onto the lettuce before cutting. Heat-treated lettuce produced significantly less hydrogen peroxide, and microbial analysis showed that E. coli O157:H7 survival on packaged, heat-treated lettuce was higher than on non–heat-treated controls. Lettuce was also cut under a solution of sodium pyruvate (a well-known hydrogen peroxide quencher), and E. coli O157:H7 survival was found to be enhanced with that treatment. When lettuce was infused with harpin before cutting, hydrogen peroxide production was enhanced, and this was associated with reduced survival of E. coli O157:H7. These results collectively support the hypothesis that modulation of wound-generated hydrogen peroxide can have an influence on E. coli O157:H7 survival on cut and packaged romaine lettuce.

Download Full-text

Inactivation of Escherichia coli O157:H7 and spoilage yeasts in germicidal UV-C-irradiated and heat-treated clear apple juice

Food Control ◽

10.1016/j.foodcont.2011.11.011 ◽

2012 ◽

Vol 25 (2) ◽

pp. 425-432 ◽

Cited By ~ 48

Author(s):

Alonzo A. Gabriel

Keyword(s):

Escherichia Coli ◽

Apple Juice ◽

Escherichia Coli O157 ◽

Spoilage Yeasts ◽

Heat Treated ◽

Uv C

Download Full-text

Bedeutung von Escherichia coli O157 beim Schlachtschaf in der Schweiz

Schweizer Archiv für Tierheilkunde ◽

10.1024/0036-7281.148.6.289 ◽

2006 ◽

Vol 148 (6) ◽

pp. 289-295 ◽

Cited By ~ 8

Author(s):

C. Zweifel ◽

M. Kaufmann ◽

J. Blanco ◽

R. Stephan

Keyword(s):

Escherichia Coli ◽

Escherichia Coli O157

Download Full-text

Molecular profiling and antimicrobial susceptibility of Escherichia coli O157:H7 isolated in Bulgaria

BULGARIAN JOURNAL OF VETERINARY MEDICINE ◽

10.15547/bjvm.2263 ◽

2020 ◽

Vol 23 (3) ◽

pp. 310-318

Author(s):

K. Koev ◽

T. Stoyanchev ◽

G. Zhelev ◽

P. Marutsov ◽

K. Gospodinova ◽

...

Keyword(s):

Escherichia Coli ◽

Escherichia Coli O157 ◽

Acid Sensitivity ◽

Lower Extent ◽

Phenotype Analysis ◽

Anal Swab ◽

Amoxicillin Clavulanic Acid ◽

Primary Identification ◽

Stx1 Gene ◽

Cattle Farms

The purpose of this study was to detect the presence of shiga-toxin producing Escherichia coli (STEC) in faeces of healthy dairy cattle and to determine the sensitivity of isolates to several antimicrobial drugs. A total of 1,104 anal swab samples originating from 28 cattle farms were examined. After the primary identification, 30 strains were found to belong to serogroup О157. By means of conventional multiplex PCR, isolates were screened for presence of resistance genes stx1, stx2 and eaeА. Twenty-nine strains possesses amplicons with a size corresponding to genes stx2 and eaeA, one had amplicons also for the stx1 gene and one lacked amplicons of all three genes. Twenty-eight strains demonstrated amplicons equivalent to gene H7. The results from phenotype analysis of resistance showed preserved sensitivity to ceftriaxone, ceftazidime, cefotaxime, cephalothin, streptomycin, gentamicin, tetracycline, enrofloxacin and combinations sulfamethoxazole/trimethoprim and amoxicillin/clavulanic acid. Sensitivity to ampicillin was relatively preserved, although at a lower extent.

Download Full-text