Search results for "Escherichia coli O157"
showing 10 items of 10 documents
Roles for RpoS in survival of Escherichia coli during protozoan predation and in reduced moisture conditions highlight its importance in soil environ…
2017
The soil is a complex ecosystem where interactions between biotic and abiotic factors determine the survival and fate of microbial inhabitants of the system. Having previously shown that Escherichia coli requires the general stress response regulator, RpoS, to survive long term in soil, it was important to determine what specific conditions in this environment necessitate a functional RpoS. This study investigated the susceptibility of soil-persistent E. coli to predation by the single-celled eukaryotes Acanthamoeba polyphaga and Tetrahymena pyriformis, and the role RpoS plays in resisting this predation. Strain-specific differences were observed in the predation of E. coli strains, with so…
Application of propidium monoazide-qPCR to evaluate the ultrasonic inactivation of Escherichia coli O157:H7 in fresh-cut vegetable wash water.
2012
The efficacy of sanitizing technologies in produce or in vegetable wash water is generally evaluated by plate count in selective media. This procedure is time consuming and can lead to misinterpretations because environmental conditions and sanitizing processes may affect bacterial growth or culturable capability. Thus, the aim of this study was to determine the applicability of a propidium monoazide real-time PCR (PMA-qPCR) method to monitor the inactivation by ultrasound treatment of foodborne bacteria in fresh-cut vegetable wash water. To this aim, lettuce wash water was artificially inoculated with Escherichia coli O157:H7 (10⁶ CFU/mL) and treated by means of a continuous ultrasonic irr…
Application of propidium monoazide quantitative PCR for selective detection of live Escherichia coli O157:H7 in vegetables after inactivation by esse…
2012
The use of propidium monoazide (PMA) is enjoying increased popularity among researchers in different fields of microbiology. Its use in combination with real-time PCR (qPCR) represents one of the most successful approaches to detect viable cells. PMA-qPCR has successfully been used to evaluate the efficacy of various disinfection technologies in different microorganisms. Initially, in this study the effect of four essential oils (EOs), cumin, clove, oregano and cinnamon, was evaluated on suspensions of the enterohemorrhagic Escherichia coli O157:H7 by PMA-qPCR, LIVE/DEAD BacLight flow cytometry analysis (LIVE/DEAD-FCM), and plate count. E. coli O157:H7 cells treated with EOs at killing conc…
Study on carvacrol and cinnamaldehyde polymeric films: mechanical properties, release kinetics and antibacterial and antibiofilm activities.
2012
Polyethylene-co-vinylacetate (EVA) films with different concentrations (3.5 wt% and 7 wt%) of essential oil constituents, carvacrol or cinnamaldehyde, were prepared and characterized by mechanical, antibacterial and antibiofilm properties. The incorporation of the compounds into copolymer films affected their elastic modulus, tensile stress and elongation at break. Carvacrol and cinnamaldehyde act as plasticizers which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the film. The analysis of the surface characteristics demonstrated that essential oil constituents lowered the contact angle values without causing any remarkable variation…
A multiplex RTi-PCR reaction for simultaneous detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus on fresh, minimally pr…
2007
In this work, a new multiplex single-tube real-time PCR approach is presented for the detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus, three of the more frequent food-borne bacterial pathogens that are usually investigated in a variety of food matrices. The study includes the design and specificity testing, of a new primer and probe specific for Salmonella spp. Reaction conditions were adjusted for the simultaneous amplification and detection of specific fragments in the beta-glucuronidase (uidA, E. coli) and Thermonulease (nuc, Sta. aureus) genes, and in the replication origin sequence (oriC, Salmonella spp.). Melting-curve analysis using a SYBR Green I RTi…
Comparison of Four Commercial DNA Extraction Kits for PCR Detection of Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Staphylococc…
2008
Four commercial DNA extraction methods, PrepMan Ultra (Applied Biosystems), InstaGene Matrix (BioRad), DNeasy Tissue kit (Qiagen), and UltraClean (MoBio), were tested for PCR detection of Listeria monocytogenes, Escherichia coli O157: H7, Salmonella, and Staphylococcus aureus in fresh, minimally processed vegetables. For comparative purposes, sensitivity assays with specific PCRs were carried out after DNA extraction with the four methods in green pepper, broccoli, and onion artificially inoculated with the four pathogens separately. As confirmed by statistical analysis, the DNeasy Tissue kit rendered the highest sensitivity values in the three matrices assayed for Salmonella, L. monocytoge…
[The risk of Escherichia coli O157:H7 in Sicily, through imported bovines for slaughter]
2001
The presence of Escherichia coli 0157:117, an emerging pathogen that has been. responsible of serious epidemics of hemorrhagic colitis and hemolytic-uremic syndrome in several countries, has been detected in rectal swabs in 13 out of 201 (6,5%) calves imported in Sicily (Italy) from France, 7 out of 154 (4,5%) calves imported from Spain, and only one out of 207 (0,5%) calves from Sicilian farms. The only positive Sicilian calf was from a farm where imported calves had been stalled some days before. All the isolates showed eaeA and hlyA virulence genes. Genes for verocytotoxins were detected in 18 isolates, which showed the following genotypes: stx2c (12 isolates), stxl stx2 (4 isolates), sa…
Microbial and chemical origins of the bactericidal activity of thermally treated yellow mustard powder toward Escherichia coli O157:H7 during dry sau…
2010
Abstract Work examines the origin of bactericidal activity in mustard flour and explores the relative contribution from starter cultures, E. coli O157:H7 itself and other sources. Bacteria can degrade naturally occurring glucosinolates in mustard and form isothiocyanates with antimicrobial activity. In the present work, 24 starter cultures (mostly from commercial mixtures) were screened for their capacity to decompose the glucosinolate, sinalbin. The most active pair, Pediococcus pentosaceus UM 121P and Staphylococcus carnosus UM 123M, were used together for the production of dry fermented sausage contaminated with E. coli O157:H7 (~ 6.5 log CFU/g). They were compared to industrial starters…
Characterization of Shiga toxin-producing Escherichia coli O157:H7 isolated in Italy and in France
2002
ABSTRACT Twenty-one Escherichia coli O157:H7 strains isolated in northern Italy from sporadic cases of hemolytic-uremic syndrome and from cattle and food were characterized by virulence gene analysis, pulsed-field gel electrophoresis (PFGE) of Xba I-digested DNA, enterobacterial repetitive intergenic consensus (ERIC) sequence-based PCR (ERIC-PCR), and antibiotic resistance patterns and compared to 18 strains isolated in France from human cases of diarrhea, cattle, and the environment. Strains isolated in Sicily (southern Italy) from a local farm (one strain) and from calves just imported from France (11 strains) and Spain (six strains) were also typed. Whereas the eae and hlyA genes were al…
Comparative efficacy of Zataria multiflora Boiss., Origanum compactum and Eugenia caryophyllus essential oils against E. coli O157:H7, feline caliciv…
2013
Abstract Ready-to-eat salads using baby-leaf and multi-leaf mixes are one of the most promising developments in the fresh-cut food industry. There is great interest in developing novel decontamination treatments, which are both safe for consumers and more efficient against foodborne pathogens. In this study, emulsions of essential oils (EOs) from Origanum compactum (oregano), Eugenia caryophyllus (clove), and Zataria multiflora Boiss (zataria) were applied by spray (0.8 ml) after the sanitizing washing step. The aim was to investigate their ability to control the growth of potentially cross-contaminating pathogens and endogenous microbiota in commercial baby leaves, processed in a fresh-cut…