Genotype Cluster Analysis in PathogenicEscherichia coliIsolates Producing Different CDT Types

Abstract

Diarrheagenic and uropathogenic E. coli types are mainly characterized by the expression of distinctive bacterial virulent factors. stx1, stx2 (Shiga toxins), and cdt (cytolethal distending toxin) genes have been acquired by horizontal gene transfer. Some virulent genes such as espP (serine protease), etpD (part of secretion pathway), and katP (catalase-peroxidase), or sfpA gene (Sfp fimbriae), are on plasmids and the others like fliC (flagellin) and the fimH gene (fimbriae type-I) are located on chromosome. Genomic pathogenicity islands (PAIs) carry some virulent genes such as hly gene. To determine the existence of virulence genes in cdt clinical isolates, genes including stx1, stx2, cdt, hly, espP, katP, sfpA, etpD, fliC, and fimH were assessed by Polymerase Chain Reaction (PCR). The most prevalent isolates for etpD and katP genes were 85.7% in cdtII. katP gene was also observed 83.3% in cdtI. However, in 42.85% of cdtIII isolates, espP gene was the most detected. Moreover, hly gene was also the most prominent gene in cdtIII (71.42%). sfpA gene was observed in 66.6% of cdtV. stx1 gene was detected in 100% of cdtII, cdtIV, and cdtV types. Presence and pattern of virulence genes were considered among cdt positive isotypes and used for their clustering and profiling.

Multiple antimicrobial resistance of <i>Escherichia coli</i> and <i>Salmonella</i> species isolated from broilers and local chickens retailed along the roadside in Zaria, Nigeria

“…Most E. coli strains are harmless and are important part of healthy human and animal intestinal tracts. However, some strains of E. coli have acquired virulence attributes and are called pathogenic E. coli (Hessain et al, 2013;Javadi et al, 2016). Pathogenic E. coli are categorized into six pathotypes (Raji et al, 2007).…”

Horizontal Gene Transfer and the Diversity of <i>Escherichia coli</i>

“…This evidence further confirms that horizontal gene transfer could occur among pathogenic strains. Moreover, findings indicate that CDT-producing strains may have originated from a common ancestor during their evolution by HGT, and they departed from each other [17].…”

“…cdt-IV operon of strain 28C is flanked on both sides by prophage-related ORFs that was indicated by a DNA homology search and it encodes putative prophage-related proteins. Phage putative proteins include a lambdoid prophage hostspecificity protein (orf1), a Lom-like protein (orf2), a putative tail fiber protein (orf3), a putative CP-933-like protease (rorf1), and a putative OmpT-like outer membrane protease (rorf2) [17]. The genome sequence of APECO1 strain revealed that the cdt-IV operon is framed by two prophages and pathogenicity island-associated DNA sequences, including integrase and tRNA genes.…”

“…The phenomenon could also be a result of extensive genetic exchanges among different phages, which might even occur in the mammalian intestine. Similar to virulence genes, morons such as orf4, orf5, orf6, cdt, rorf1, and rorf2 might have spread by horizontal [17]. cdt-I and cdt-IV genes might have been acquired by phage transduction from a common ancestor and evolution of the CDT-encoding phages in different bacterial host-generated differences in the cdt genes and their flanking DNA contents [16].…”

“…Stabilization of this cargo determinant was done by inactivation of this bacteriophage genome. It is clear that further investigations of flanking regions and P2-like prophage sequences in CDT-V-positive strains will help to clarify the evolutionary background of the distribution of these variants [14][15][16][17].…”