Alteration of the Microbiota and Virulence Gene Expression in E. coli O157:H7 in Pig Ligated Intestine with and without AE Lesions.

Background: Previously we found that E. coli O157:H7 inoculated into ligated pig intestine formed attaching and effacing (AE) lesions in some pigs but not in others. The present study evaluated changes in the microbial community and in virulence gene expression in E.

Virulence profiling of Shiga toxin-producing Escherichia coli O111:NM isolates from cattle.

Shiga toxin-producing Escherichia coli (STEC) O111:NM is an important serotype that has been incriminated in disease outbreaks in the United States. This study characterized cattle STEC O111:NM for virulence factors and markers by PCR. Major conclusions are that STEC O111:NM characterized in this study lacks stx2 and the full spectrum of nle gene markers, and it has an incomplete OI-122.

Grapefruit juice and its constituents augment the effect of low pH on inhibition of survival and adherence to intestinal epithelial cells of Salmonella enterica serovar Typhimurium PT193.

The present study examined the survival of Salmonella Typhimurium and its adherence to intestinal epithelial cells following inoculation into grapefruit juice and apple cider. Both liquids significantly inactivated S. Typhimurium (0.

Adherence and associated virulence gene expression in acid-treated Escherichia coli O157 : H7 in vitro and in ligated pig intestine.

Escherichia coli O157 : H7 cells that interact with intestinal epithelial cells in animals and humans do so after passage through the low pH of the stomach. This study compared adherence and its associated virulence gene expression in acid-treated (AT) and non-acid treated (NAT) E. coli O157 : H7 strain 86-24 in vitro and in ligated pig intestine.

Adherence of Escherichia coli O157:H7 to epithelial cells in vitro and in pig gut loops is affected by bacterial culture conditions.

The objectives of this study were to determine the effect of bacterial culture conditions on adherence of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain 86-24 in vivo to pig enterocytes and to compare the results with adherence in vitro to cultured HEp-2 and IPEC-J2 cells. Growth of O157:H7 in MacConkey broth (MB) resulted in almost no adherence to both HEp-2 and IPEC-J2 cells; prior exposure of the bacteria to pH 2.5 reduced adherence.

Relevance in pathogenesis research.

Research on pathogenesis of bacterial diseases involves exploration of the intricate and complex interactions among pathogen, host, and environment. Host-parasite-environment interactions that were relatively simple were the first to be understood. They include intoxications in which ingestion of a powerful bacterial toxin was sufficient to cause disease.

Preliminary investigations of the distribution of Escherichia coli O149 in sows, piglets, and their environment.

Little is known about the sources and kinetics of enterotoxigenic Escherichia coli colonization in pigs during the pre-and post-weaning period. In this study, farrowing pens, sows, and piglets were tested for the presence of E. coli O149 by real-time polymerase chain reaction (PCR) after bacterial culture pre-enrichment on 2 farms, one with a history of post-weaning diarrhea (problem farm - PF) and the other without such a history (non-problem farm - NPF).

Differential gene expression and adherence of Escherichia coli O157:H7 in vitro and in ligated pig intestines.

Background: Escherichia coli O157:H7 strain 86-24 grown in MacConkey broth (MB) shows almost no adherence to cultured epithelial cells but adheres well in pig ligated intestines. This study investigated the mechanisms associated with the difference between in-vitro and in-vivo adherence of the MB culture.

Methodology/principal Findings: It was found that decreased adherence in vitro by bacteria grown in MB was mainly due to lactose, possibly implicating the involvement of carbon catabolite repression (CCR).

Antimicrobial susceptibility of Flavobacterium psychrophilum isolates from Ontario.

Flavobacterium psychrophilum is the etiological agent of bacterial coldwater disease (BCWD), an important disease in the Ontario fish farming industry and in finfish aquaculture in temperate waters worldwide. The development of antimicrobial resistance by F. psychrophilum is a concern because management of outbreaks of BCWD often requires the use of antibiotics.

Verotoxin 2 enhances adherence of enterohemorrhagic Escherichia coli O157:H7 to intestinal epithelial cells and expression of {beta}1-integrin by IPEC-J2 cells.

Verotoxin (VT) has been implicated in the promotion of adherence to and colonization of intestinal epithelial cells by enterohemorrhagic Escherichia coli (EHEC) O157:H7. The present study investigated the effect of VT2 on the adherence of EHEC O157:H7 strain 86-24 to porcine jejunal (IPEC-J2), human colon (CaCo-2), and human laryngeal carcinoma (HEp-2) cell lines and on the expression in IPEC-J2 cells of synthases for beta1-integrin and nucleolin, both of which are implicated in bacterial adherence. The effect on expression of globotriaosylceramide (Gb3) synthase, the receptor for VT, was also examined.

Contributions of O island 48 to adherence of enterohemorrhagic Escherichia coli O157:H7 to epithelial cells in vitro and in ligated pig ileal loops.

O island 48 (OI-48) of Escherichia coli consists of three functional gene clusters that encode urease, tellurite resistance (Te(r)), and putative adhesins Iha and AIDA-1. The functions of these clusters in enterohemorrhagic E. coli (EHEC) O157:H7 infection are unknown.

Adherence of Escherichia coli O157:H7 mutants in vitro and in ligated pig intestines.

There are contradictory literature reports on the role of verotoxin (VT) in adherence of enterohemorrhagic Escherichia coli O157:H7 (O157 EHEC) to intestinal epithelium. There are reports that putative virulence genes of O island 7 (OI-7), OI-15, and OI-48 of this pathogen may also affect adherence in vitro. Therefore, mutants of vt2 and segments of OI-7 and genes aidA(15) (gene from OI-15) and aidA(48) (gene from OI-48) were generated and evaluated for adherence in vitro to cultured human HEp-2 and porcine jejunal epithelial (IPEC-J2) cells and in vivo to enterocytes in pig ileal loops.

Antimicrobial resistance in selected bacteria from poultry.

This paper reviews the present state of antimicrobial resistance (AMR) in the zoonotic bacteria Salmonella, Campylobacter jejuni and Campylobacter coli, and in Escherichia coli from chickens and turkeys. For Salmonella, the frequencies and patterns of AMR vary depending on time, region, serovar, the particular farm, layers versus broilers, and the antimicrobial agent. There is usually a higher frequency of AMR in Salmonella from turkeys compared with Salmonella from chickens.

Evaluation of bacteriophages for prevention and treatment of diarrhea due to experimental enterotoxigenic Escherichia coli O149 infection of pigs.

The objective of this study was to determine the efficacy of selected phages individually and in combination in prevention and treatment of diarrhea due to experimental O149:H10:F4 enterotoxigenic Escherichia coli (ETEC) in weaned pigs. For prophylaxis, the phages were administered orally shortly after challenge, and for therapeutic use, were given 24h after challenge, following the onset of diarrhea. The parameters used to assess outcomes were weight change, duration of diarrhea, severity of diarrhea, composite diarrhea score, and extent of shedding of the challenge ETEC over 6 days.

FimH adhesin of type 1 fimbriae is a potent inducer of innate antimicrobial responses which requires TLR4 and type 1 interferon signalling.

Components of bacteria have been shown to induce innate antiviral immunity via Toll-like receptors (TLRs). We have recently shown that FimH, the adhesin portion of type 1 fimbria, can induce the innate immune system via TLR4. Here we report that FimH induces potent in vitro and in vivo innate antimicrobial responses.

Production of verotoxin and distribution of O islands 122 and 43/48 among verotoxin-producing Escherichia coli O103:H2 isolates from cattle and humans.

This study investigated variations in the occurrence of markers of O islands 122 and 43/48 and in verotoxin 1 production in 91 verotoxin-producing Escherichia coli (VTEC) O103:H2 strains of bovine and human origins. None of the genes that were investigated appear to be virulence indicators for human O103:H2 VTEC.

Cutting edge: FimH adhesin of type 1 fimbriae is a novel TLR4 ligand.

Several TLR ligands of bacterial origin induce innate immune responses. Although FimH, the adhesin portion of type 1 fimbria, plays an important role in the pathogenicity of some gram-negative bacteria, its ability to stimulate the innate immune system via TLR signaling remains unclear. In this study we report that FimH induces potent innate responses in a MyD88-dependent fashion.

Prevalence and characterization of verotoxin-producing Escherichia coli (VTEC) in cattle from an Ontario abattoir.

This study determined the prevalence of verotoxin (VT)-producing Escherichia coli (VTEC) in Ontario beef cattle at slaughter and characterized the isolates by serotype, virulence factors, virulence markers, and antimicrobial resistance. Cultures of rectal feces from 500 animals were screened for VT by an enzyme-linked immunosorbent assay (ELISA) and by polymerase chain reaction (PCR) for genes vt1, vt2, and eae. The VT-ELISA-positive samples were tested by a VT-immunoblot to isolate VTEC colonies.

Phenotypic and genotypic characterization of verotoxin-producing Escherichia coli O103:H2 isolates from cattle and humans.

Characterization of important non-O157 verotoxin-producing Escherichia coli (VTEC) has lagged considerably behind that of O157:H7 strains. This study characterized 91 VTEC O103:H2 strains from bovine and human sources and of North American and European origins by virulence or putative virulence genes, pulsed-field gel electrophoresis (PFGE) patterns, plasmid profiles, antimicrobial resistance, and colicin production. All strains were positive for vt1 and eae-epsilon; 97% were positive for ehxA; and all were negative for hlyA.

Characterization of verotoxin-encoding phages from Escherichia coli O103:H2 strains of bovine and human origins.

The objectives of this study were to induce and characterize verotoxin-encoding phages from a collection of 91 verotoxin-producing Escherichia coli (VTEC) O103:H2 strains of human and bovine origins. All the strains carried the vt1 gene, and two carried the vt2 gene as well. The phages were induced by UV irradiation and characterized by DNA restriction fragment length polymorphism (RFLP), genome size, morphology, and Q and P genes, characteristic of lambdoid phages.

Effect of plasmid pTENT2 on severity of porcine post-weaning diarrhoea induced by an O149 enterotoxigenic Escherichia coli.

A particularly virulent O149:H10 enterotoxigenic Escherichia coli clone harbours a newly characterized plasmid pTENT2 carrying the tetracycline-resistance tetA and the virulence genes estA, paa, and sepA that were not present in less virulent clones. The objectives of this study were to assess whether the additional genes on pTENT2 played a role in the increased severity of post-weaning diarrhoea and if they provided any potential advantage for the emergence of the highly virulent clone. Groups of pigs were dosed orally with isogenic pTENT2-positive and pTENT2-negative ETEC strains, and the clinical and pathological changes were compared between the groups.

A homolog of the O157 urease-encoding O island 48 is present in porcine O149:H10 enterotoxigenic Escherichia coli.

The relationship of the urease operon in the highly virulent O149 porcine enterotoxigenic Escherichia coli (ETEC) strain Ro8 to a genomic island (GI) homologous to O island (OI) 48 of O157 enterohemorrhagic E. coli (EHEC) strain EDL933 was investigated. Eighty-four of 84 O149:H10 strains were urease positive whereas 44 of 44 O149:H43 porcine ETEC strains were urease-negative.

PagP activation in the outer membrane triggers R3 core oligosaccharide truncation in the cytoplasm of Escherichia coli O157:H7.

The Escherichia coli outer membrane phospholipid:lipid A palmitoyltransferase PagP is normally a latent enzyme, but it can be directly activated in outer membranes by lipid redistribution associated with a breach in the permeability barrier. We now demonstrate that a lipid A myristate deficiency in an E. coli O157:H7 msbB mutant constitutively activates PagP in outer membranes.