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1.  Education for practitioners and patients 
The Australasian Medical Journal  2013;6(12):724-726.
doi:10.4066/AMJ.2013.1952
PMCID: PMC3877856  PMID: 24391685
2.  Campylobacter-Induced Interleukin-8 Secretion in Polarized Human Intestinal Epithelial Cells Requires Campylobacter-Secreted Cytolethal Distending Toxin- and Toll-Like Receptor-Mediated Activation of NF-κB ▿  
Infection and Immunity  2008;76(10):4498-4508.
Campylobacter jejuni and Campylobacter coli colonize and infect the intestinal epithelium and cause acute inflammatory diarrhea. The intestinal epithelium serves as a physical barrier to, and a sensor of, bacterial infection by secreting proinflammatory cytokines. This study examined the mechanisms for Campylobacter-induced secretion of the proinflammatory chemokine interleukin-8 (IL-8) by using polarized T84 human colonic epithelial cells as a model. C. jejuni increased the secretion of both IL-8 and tumor necrosis factor alpha (TNF-α) in polarized epithelial cells. However, the increase in IL-8 secretion was independent of Campylobacter-stimulated TNF-α secretion. Polarized T84 cells secreted IL-8 predominantly to the basolateral medium independently of the inoculation direction. While there was a significant correlation between the levels of IL-8 secretion and Campylobacter invasion, all 11 strains tested increased IL-8 secretion by polarized T84 cells despite their differences in adherence, invasion, and transcytosis efficiencies. Cell-free supernatants of Campylobacter-T84-cell culture increased IL-8 secretion to levels similar to those induced by live bacterial inoculation. The ability of the supernatant to induce IL-8 secretion was reduced by flagellum and cytolethal distending toxin (CDT) gene mutants, treatment of the supernatant with protease K or heat, or treatment of T84 cells with the Toll-like receptor (TLR) inhibitor MyD88 inhibitory peptide or chloroquine. NF-κB inhibitors or cdtB mutation plus MyD88 inhibitor, but not flaA cdtB double mutations, abolished the ability of the supernatant to induce IL-8 secretion. Taken together, our results demonstrate that Campylobacter-induced IL-8 secretion requires functional flagella and CDT and depends on the activation of NF-κB through TLR signaling and CDT in human intestinal epithelial cells.
doi:10.1128/IAI.01317-07
PMCID: PMC2546826  PMID: 18644884
3.  Identification and Characterization of Shiga Toxin Type 2 Variants in Escherichia coli Isolates from Animals, Food, and Humans▿  
Applied and Environmental Microbiology  2008;74(18):5645-5652.
There is considerable heterogeneity among the Shiga toxin type 2 (Stx2) toxins elaborated by Shiga toxin-producing Escherichia coli (STEC). One such Stx2 variant, the Stx2d mucus-activatable toxin (Stx2dact), is rendered more toxic by the action of elastase present in intestinal mucus, which cleaves the last two amino acids of the A2 portion of the toxin A subunit. We screened 153 STEC isolates from food, animals, and humans for the gene encoding Stx2dact by using a novel one-step PCR procedure. This method targeted the region of stx2dact that encodes the elastase recognition site. The presence of stx2dact was confirmed by DNA sequencing of the complete toxin genes. Seven STEC isolates from cows (four isolates), meat (two isolates), and a human (one isolate) that carried the putative stx2dact gene were identified; all were eae negative, and none was the O157:H7 serotype. Three of the isolates (CVM9322, CVM9557, and CVM9584) also carried stx1, two (P1332 and P1334) carried stx1 and stx2c, and one (CL-15) carried stx2c. One isolate, P1130, harbored only stx2dact. The Vero cell cytotoxicities of supernatants from P1130 and stx1 deletion mutants of CVM9322, CVM9557, and CVM9584 were increased 13- to 30-fold after treatment with porcine elastase. Thus, Stx2dact-producing strains, as detected by our one-step PCR method, can be isolated not only from humans, as previously documented, but also from food and animals. The latter finding has important public health implications based on a recent report from Europe of a link between disease severity and infection with STEC isolates that produce Stx2dact.
doi:10.1128/AEM.00503-08
PMCID: PMC2547040  PMID: 18658282
4.  Attributing Illness to Food 
Emerging Infectious Diseases  2005;11(7):993-999.
Identification and prioritization of effective food safety interventions require an understanding of the relationship between food and pathogen from farm to consumption. Critical to this cause is food attribution, the capacity to attribute cases of foodborne disease to the food vehicle or other source responsible for illness. A wide variety of food attribution approaches and data are used around the world, including the analysis of outbreak data, case-control studies, microbial subtyping and source tracking methods, and expert judgment, among others. The Food Safety Research Consortium sponsored the Food Attribution Data Workshop in October 2003 to discuss the virtues and limitations of these approaches and to identify future options for collecting food attribution data in the United States. We summarize workshop discussions and identify challenges that affect progress in this critical component of a risk-based approach to improving food safety.
doi:10.3201/eid1107.040634
PMCID: PMC3371809  PMID: 16022770
Campylobacter; outbreaks; Risk Assessment; risk factors; Salmonella; organizational models
5.  Microbial Diversity of Biofilms in Dental Unit Water Systems 
We investigated the microbial diversity of biofilms found in dental unit water systems (DUWS) by three methods. The first was microscopic examination by scanning electron microscopy (SEM), acridine orange staining, and fluorescent in situ hybridization (FISH). Most bacteria present in the biofilm were viable. FISH detected the β and γ, but not the α, subclasses of Proteobacteria. In the second method, 55 cultivated biofilm isolates were identified with the Biolog system, fatty acid analysis, and 16S ribosomal DNA (rDNA) sequencing. Only 16S identified all 55 isolates, which represented 13 genera. The most common organisms, as shown by analyses of 16S rDNA, belonged to the genera Afipia (28%) and Sphingomonas (16%). The third method was a culture-independent direct amplification and sequencing of 165 subclones from community biofilm 16S rDNA. This method revealed 40 genera: the most common ones included Leptospira (20%), Sphingomonas (14%), Bacillus (7%), Escherichia (6%), Geobacter (5%), and Pseudomonas (5%). Some of these organisms may be opportunistic pathogens. Our results have demonstrated that a biofilm in a health care setting may harbor a vast diversity of organisms. The results also reflect the limitations of culture-based techniques to detect and identify bacteria. Although this is the greatest diversity reported in DUWS biofilms, other genera may have been missed. Using a technique based on jackknife subsampling, we projected that a 25-fold increase in the number of subclones sequenced would approximately double the number of genera observed, reflecting the richness and high diversity of microbial communities in these biofilms.
doi:10.1128/AEM.69.6.3412-3420.2003
PMCID: PMC161485  PMID: 12788744

Results 1-5 (5)