Evaluating the Pathogenic Potential of Environmental Escherichia coli by Using the Caenorhabditis elegans Infection Model

Abstract

The detection and abundance of Escherichia coli in water is used to monitor and mandate the quality of drinking and recreational water. Distinguishing commensal waterborne E. coli isolates from those that cause diarrhea or extraintestinal disease in humans is important for quantifying human health risk. A DNA microarray was used to evaluate the distribution of virulence genes in 148 E. coli environmental isolates from a watershed in eastern Ontario, Canada, and in eight clinical isolates. Their pathogenic potential was evaluated with Caenorhabditis elegans, and the concordance between the bioassay result and the pathotype deduced by genotyping was explored. Isolates identified as potentially pathogenic on the basis of their complement of virulence genes were significantly more likely to be pathogenic to C. elegans than those determined to be potentially nonpathogenic. A number of isolates that were identified as nonpathogenic on the basis of genotyping were pathogenic in the infection assay, suggesting that genotyping did not capture all potentially pathogenic types. The detection of the adhesin-encoding genes sfaD, focA, and focG, which encode adhesins; of iroN 2 , which encodes a siderophore receptor; of pic, which encodes an autotransporter protein; and of b1432, which encodes a putative transposase, was significantly associated with pathogenicity in the infection assay. Overall, E. coli isolates predicted to be pathogenic on the basis of genotyping were indeed so in the C. elegans infection assay. Furthermore, the detection of C. elegans-infective environmental isolates predicted to be nonpathogenic on the basis of genotyping suggests that there are hitherto-unrecognized virulence factors or combinations thereof that are important in the establishment of infection.

Virulence behavior of uropathogenic Escherichia coli strains in the host model Caenorhabditis elegans

“…Concerning the presence of virulence factors, both bacterial strains possessed hly A gene, although ECP110 strain showed a delayed hemolytic activity. Different reports indicate that UPEC strains that express HlyA were associated with more severe clinical outcomes (Merkx‐Jacques et al, ). In the epithelial cell line HEp‐2, the in vitro model utilized in this study, both ECP45 and ECP110 were able to adhere and invade to a extent and they were unable to survive in cell monolayers.…”

“…Concerning the presence of virulence factors, both bacterial strains possessed hlyA gene, although ECP110 strain showed a delayed hemolytic activity. Different reports indicate that UPEC strains that express HlyA were associated with more severe clinical outcomes (Merkx-Jacques et al, 2013). In the epithelial cell line…”

“…C. elegans , an ubiquitous free‐living nematode which lives in soil and feeds on bacteria, sharing with humans many biological pathways, has become a widely used model organism for studying host interactions with microbes and virulence mechanisms of microbial infections (Anyanful et al, ; Barber, Norton, Wiles, & Mulvey, ; Burton, Pendergast, & Aballay, ; Mylonakis, Ausubel, Tang, & Calderwood, ). It has been reported that free‐living nematodes may serve as carriers or vectors of human enteric pathogens from soil resources, and these nematodes have been shown to be resistant to free chlorine and to offer protection to ingested pathogens against chemical sanitizers (Caldwell, Adler, Anderson, Williams, & Beuchat, ; Merkx‐Jacques et al, ).…”

“…It has been reported that free-living nematodes may serve as carriers or vectors of human enteric pathogens from soil resources, and these nematodes have been shown to be resistant to free chlorine and to offer protection to ingested pathogens against chemical sanitizers (Caldwell, Adler, Anderson, Williams, & Beuchat, 2003;Merkx-Jacques et al, 2013).…”

Synthesis of magnetic framework composites for the discrimination of Escherichia coli at the strain level

“…Two important human pathogens E. coli O127:H6 (strain E2348/69) and E. coli O78:H11 (strain H10407) were selected as suitable bacterial samples to evaluate the performance of the composites in obtaining strain-specific MALDI-TOF MS profiles [26]. The synthesis protocol of Fe 3 O 4 -COOH@MIL-101 composites and flowchart of fast and convenient enrichment of biomarkers from cell lysates using Fe 3 O 4 -COOH@MIL-101 composites are presented in Scheme 1.…”