Phylogeographic Analysis Reveals Multiple International transmission Events Have Driven the Global Emergence of Escherichia coli O157:H7.

Background: Shiga toxin-producing Escherchia coli (STEC) O157:H7 is a zoonotic pathogen that causes numerous food and waterborne disease outbreaks. It is globally distributed, but its origin and the temporal sequence of its geographical spread are unknown.

Methods: We analyzed whole-genome sequencing data of 757 isolates from 4 continents, and performed a pan-genome analysis to identify the core genome and, from this, extracted single-nucleotide polymorphisms.

Silver nanoparticles: A novel antibacterial agent for control of Cronobacter sakazakii.

Silver nanoparticles (AgNP) have been widely applied because of their broad spectrum of antimicrobial activities against bacteria, fungi, and viruses. However, little research has been done to evaluate their effects on Cronobacter sakazakii, an opportunistic pathogen usually infecting infants and having a high fatality rate. The aims of this work were to investigate the antibacterial property of novel, synthesized, positively charged silver nanoparticles against C.

Analysis of the Population Structure among Isolates from 1931 to 2015 in Australia.

Listeriosis remains among the most important bacterial illnesses, with a high associated mortality rate. Efforts to control listeriosis require detailed knowledge of the epidemiology of the disease itself, and its etiological bacterium, . In this study we provide an in-depth analysis of the epidemiology of 224 isolates from Australian clinical and non-clinical sources.

Physiological Response of Escherichia coli O157:H7 Sakai to Dynamic Changes in Temperature and Water Activity as Experienced during Carcass Chilling.

Enterohemeorrhagic Escherichia coli is a leading cause of foodborne illness, with the majority of cases linked to foods of bovine origin. Currently, no completely effective method for controlling this pathogen during carcass processing exists. Understanding how this pathogen behaves under those stress conditions experienced on the carcass during chilling in cold air could offer opportunities for development or improvement of effective decontamination processes.

Strategies to enable the adoption of animal biotechnology to sustainably improve global food safety and security.

The ability to generate transgenic animals has existed for over 30 years, and from those early days many predicted that the technology would have beneficial applications in agriculture. Numerous transgenic agricultural animals now exist, however to date only one product from a transgenic animal has been approved for the food chain, due in part to cumbersome regulations. Recently, new techniques such as precision breeding have emerged, which enables the introduction of desired traits without the use of transgenes.

Prevalence, seasonality, and growth of enterococci in raw and pasteurized milk in Victoria, Australia.

This study investigated the prevalence, seasonality, and species variety of enterococci present in raw milk factory silos and pasteurized milk in 3 dairying regions in Victoria, Australia, over a 1-yr period. Additionally, the growth ability of thermoduric enterococci isolated in this study (Enterococcus faecalis, E. faecium, E.

Geographically distinct Escherichia coli O157 isolates differ by lineage, Shiga toxin genotype, and total shiga toxin production.

While the differential association of Escherichia coli O157 genotypes with animal and human hosts has recently been well documented, little is known about their distribution between countries and how this might affect regional disease rates. Here, we used a 48-plex single nucleotide polymorphism (SNP) assay to segregate 148 E. coli O157 isolates from Australia, Argentina, and the United States into 11 SNP lineages.

Exploiting the explosion of information associated with whole genome sequencing to tackle Shiga toxin-producing Escherichia coli (STEC) in global food production systems.

The rates of foodborne disease caused by gastrointestinal pathogens continue to be a concern in both the developed and developing worlds. The growing world population, the increasing complexity of agri-food networks and the wide range of foods now associated with STEC are potential drivers for increased risk of human disease. It is vital that new developments in technology, such as whole genome sequencing (WGS), are effectively utilized to help address the issues associated with these pathogenic microorganisms.

Global genome response of Escherichia coli O157∶H7 Sakai during dynamic changes in growth kinetics induced by an abrupt temperature downshift.

Escherichia coli O157∶H7 is a mesophilic food-borne pathogen. We investigated the growth kinetics of E. coli O157∶H7 Sakai during an abrupt temperature downshift from 35°C to either 20°C, 17°C, 14°C or 10°C; as well as the molecular mechanisms enabling growth after cold stress upon an abrupt downshift from 35°C to 14°C in an integrated transcriptomic and proteomic analysis.

Escherichia coli strains expressing H12 antigens demonstrate an increased ability to attach to abiotic surfaces as compared with E. coli strains expressing H7 antigens.

The role of Escherichia coli H antigens in hydrophobicity and attachment to glass, Teflon and stainless steel (SS) surfaces was investigated through construction of fliC knockout mutants in E. coli O157:H7, O1:H7 and O157:H12. Loss of FliC(H12) in E.

Global genome response of Escherichia coli O157∶H7 Sakai during dynamic changes in growth kinetics induced by an abrupt downshift in water activity.

The present study was undertaken to investigate growth kinetics and time-dependent change in global expression of Escherichia coli O157∶H7 Sakai upon an abrupt downshift in water activity (aw). Based on viable count data, shifting E. coli from aw 0.

Multilocus genotype analysis of Escherichia coli O157 isolates from Australia and the United States provides evidence of geographic divergence.

Escherichia coli O157 is a food-borne pathogen whose major reservoir has been identified as cattle. Recent genetic information has indicated that populations of E. coli O157 from cattle and humans can differ genetically and that this variation may have an impact on their ability to cause severe human disease.

Pathogenic Escherichia coli and One Health implications.

Escherichia coli are common inhabitants in the intestinal tracts of warm blooded animals where they generally cause no harm to the host, although there are some types of E. coli which are able to cause disease. The most significant of these are enterohaemorrhagic E.

Phylogenetically related Argentinean and Australian Escherichia coli O157 isolates are distinguished by virulence clades and alternative Shiga toxin 1 and 2 prophages.

Shiga toxigenic Escherichia coli O157 is the leading cause of hemolytic uremic syndrome (HUS) worldwide. The frequencies of stx genotypes and the incidences of O157-related illness and HUS vary significantly between Argentina and Australia. Locus-specific polymorphism analysis revealed that lineage I/II (LI/II) E.

Heat resistance of thermoduric enterococci isolated from milk.

Enterococci are reported to survive pasteurisation but the extent of their survival is unclear. Sixty-one thermoduric enterococci isolates were selected from laboratory pasteurised milk obtained from silos in six dairy factories. The isolates were screened to determine log(10) reductions incurred after pasteurisation (63°C/30 min) and ranked from highest to lowest log(10) reduction.

Integrated transcriptomic and proteomic analysis of the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions of cold and water activity stress.

An integrated transcriptomic and proteomic analysis was undertaken to determine the physiological response of Escherichia coli O157:H7 Sakai to steady-state conditions relevant to low temperature and water activity conditions experienced during meat carcass chilling in cold air. The response of E. coli during exponential growth at 25 °C a(w) 0.

CsgA production by Escherichia coli O157:H7 alters attachment to abiotic surfaces in some growth environments.

The role of curli expression in attachment of Escherichia coli O157:H7 to glass, Teflon, and stainless steel (SS) was investigated through the creation of csgA knockout mutants in two isolates of E. coli O157:H7. Attachment assays using epifluorescence microscopy and measurements of the force of adhesion of bacterial cells to the substrates using atomic force microscopy (AFM) force mapping were used to determine differences in attachment between wild-type (wt) and csgA-negative (ΔcsgA) strains following growth in four different media.

Surface roughness of stainless steel influences attachment and detachment of Escherichia coli O157.

Determining the influence of surface roughness on Escherichia coli O157 attachment to and detachment from stainless steel (SS) is important for controlling this foodborne pathogen. The aim of this study was to evaluate the interactions of six E. coli strains (four O157:H7, one O157:H12, and one O1:H7) with SS type 304 finishes of various surface roughness: 2B (unpolished surface), 4 (common food grade SS), and 8 (polished smooth surface).

The DNA protection during starvation protein (Dps) influences attachment of Escherichia coli to abiotic surfaces.

The attachment of bacterial species such as Escherichia coli to abiotic materials is of concern to the food industry. This study investigated the role of DNA protection during starvation protein (Dps) in cell surface hydrophobicity and attachment of E. coli to glass, stainless steel, and Teflon surfaces.

Transcriptomic analysis of Escherichia coli O157:H7 and K-12 cultures exposed to inorganic and organic acids in stationary phase reveals acidulant- and strain-specific acid tolerance responses.

The food-borne pathogen Escherichia coli O157:H7 is commonly exposed to organic acid in processed and preserved foods, allowing adaptation and the development of tolerance to pH levels otherwise lethal. Since little is known about the molecular basis of adaptation of E. coli to organic acids, we studied K-12 MG1655 and O157:H7 Sakai during exposure to acetic, lactic, and hydrochloric acid at pH 5.

Integron-containing bacteria in faeces of cattle from different production systems at slaughter.

Aims: To determine the prevalence and characteristics of integron-containing bacteria in faeces of cattle from grass-fed, lot-fed, or organically produced cattle.

Methods And Results: Faecal samples from grass-fed (n = 125), lot-fed (n = 125) and organic (n = 135) cattle were tested for the presence of class 1 and class 2 integrons by using PCR and colony hybridisation. The prevalence of class 1 and class 2 integrase were higher in lot-fed cattle (71% and 62%) than grass-fed cattle (52% and 30%) which in turn were higher than organic cattle (25% and 11%).

International comparison of clinical, bovine, and environmental Escherichia coli O157 isolates on the basis of Shiga toxin-encoding bacteriophage insertion site genotypes.

Escherichia coli O157:H7 genotypes in the bovine reservoir may differ in virulence. The proportion of clinical genotypes among cattle isolates was weakly (P = 0.054) related to the international incidence of E.

EhaA is a novel autotransporter protein of enterohemorrhagic Escherichia coli O157:H7 that contributes to adhesion and biofilm formation.

Autotransporter (AT) proteins have been identified in many Gram-negative pathogens and are unique in that their primary sequence is sufficient to direct their transport across the bacterial membrane system. Where characterized they are uniformly associated with virulence. Using conserved AT motifs as a search tool, four putative AT proteins were identified in the Enterohemorrhagic Escherichia coli O157:H7 EDL933 genome.

A comparison of antibiotic resistance integrons in cattle from separate beef meat production systems at slaughter.

Aims: To compare antibiotic resistance integrons in cattle from three separate grass-fed, grain-fed and certified organic cattle production systems at slaughter.

Methods And Results: In this study 198 samples from three separate cattle production systems were tested by PCR for the presence of class 1 and class 2 integrons. Integron-containing bacteria were readily isolated from pen faeces and hide samples regardless of production system.

Diverse class 2 integrons in bacteria from beef cattle sources.

Objectives: The purpose of this study was to determine the diversity of class 2 integrons in bacteria isolated from beef cattle sources.

Methods: The variable regions of a subset of 11 class 2 integron-containing bacteria were analysed by PCR and DNA sequencing for the presence of novel rearrangements.

Results: A total of six different class 2 integron arrays were identified and four of these were fully characterized.