Molecular and Antimicrobial Susceptibility Analyses Distinguish Clinical from Bovine Escherichia coli O157 Strains

Abstract

A population-based study combining (i) antimicrobial, (ii) genetic, and (iii) virulence analyses with molecular evolutionary analyses revealed segregative characteristics distinguishing human clinical and bovine Escherichia coli O157 strains from western Canada. Human (n ‫؍‬ 50) and bovine (n ‫؍‬ 50) strains of E. coli O157 were collected from Saskatchewan and Manitoba in 2006 and were analyzed by using the six-marker lineage-specific polymorphism assay (LSPA6), antimicrobial susceptibility analysis, the colicin assay, plasmid and virulence profiling including the eae, ehxA, espA, iha, stx 1 , stx 2 , stx 2c , stx 2d , stx 2d-activatable , stx 2e , and stx 2f virulence-associated genes, and structure analyses. Multivariate logistic regression and Fisher's exact test strongly suggested that antimicrobial susceptibility was the most distinctive characteristic (P ‫؍‬ 0.00487) associated with human strains. Among all genetic, virulence, and antimicrobial determinants, resistance to tetracycline (P < 0.000) and to sulfisoxazole (P < 0.009) were the most strongly associated segregative characteristics of bovine E. coli O157 strains. Among 11 virulence-associated genes, stx 2c showed the strongest association with E. coli O157 strains of bovine origin. LSPA6 genotyping showed the dominance of the lineage I genotype among clinical (90%) and bovine (70%) strains, indicating the importance of lineage I in O157 epidemiology and ecology. Population structure analysis revealed that the more-diverse bovine strains came from a unique group of strains characterized by a high degree of antimicrobial resistance and high frequencies of lineage II genotypes and stx 2c variants. These findings imply that antimicrobial resistance generated among bovine strains of E. coli O157 has a large impact on the population of this human pathogen.

Antibiotic‐resistant Shiga toxin‐producing Escherichia coli: An overview of prevalence and intervention strategies

“…Likewise, Stephan & Schumacher () reported higher levels of antibiotic resistance among swine (75%) and beef (34.8%) compared to human (27.7%) non‐O157 STEC isolates in Switzerland. Vidovic et al () reported a significantly higher percentage of bovine O157 strains, obtained from Western Canada, being resistant to tetracycline (36% of the bovine versus 4% of the clinical strains), sulfisoxazole (60% versus 30%) and streptomycin (16% versus 4%). The reason for this difference in prevalence of AR‐STEC is not known but these studies suggest that there is a prevalence of resistance among STEC isolates from both animal and human sources.…”

ZnO Nanoparticles Impose a Panmetabolic Toxic Effect Along with Strong Necrosis, Inducing Activation of the Envelope Stress Response in Salmonella enterica Serovar Enteritidis

“…After only several years following the emergence of vancomycin resistance, plasmids carrying genes for vancomycin resistance shifted into already multiple-drug-resistant strains of Enterococcus faecium, triggering the spread of a virtually untreatable pathogen, compounding the growing problem of nosocomial infections in U.S. hospitals (3). Besides the use of antibiotics for human treatments, the common use of veterinary antimicrobials and especially the industrial-scale incorporation of antimicrobial growth promoters as additives in feed have significantly contributed to the emergence of antibiotic-resistant bacteria (1,4,5). This not only complicates anti-infective therapeutics but also heightens the need for developing alternative approaches to more effectively control infectious diseases and, in particular, to slow the emergence of antimicrobial resistance.…”

Detection and Typing Strategies for Pathogenic Escherichia coli

“…This media failed to detect only 5/249 from three published studies (Hirvonen et al 2012;Tzschoppe et al 2012;Gouali et al 2013;Wylie et al 2013). CHROMagar™ was found to have good performance in a clinical trial of stool specimens and was found to recover different STEC serotypes including non-sorbitol fermenting E. coli O157:H7 and O104:H4.…”

“…The LSPA-6 assay has been used to analyze populations of E. coli O157:H7 from a diverse array of countries including Canada, the USA, Australia, Argentina, Japan, and the Netherlands Lee et al 2011;Mellor et al 2012Sharma et al 2009;Vidovic et al 2013;Ziebell et al 2008a). This has led to some interesting observations around geographic diversity of E. coli O157:H7 populations and confirmation of the association of clinical isolates with Designation 2 2 2 2 2 or 3 2 or 3 a As new allele sizes have been discovered, additional designations have been determined although there has been no consistency between different publications.…”

“…Even within countries, geographical differences in the distribution of E. coli O157:H7 LSPA-6 lineages may occur, as isolates of LSPA-6 lineage I were significantly more likely to come from cattle in southern Alberta (92 % of all strains of southern Alberta) than from northern Alberta (28 % of all strains from northern Alberta) (Sharma et al 2009). Lee et al 2011;Mellor et al 2012Sharma et al 2009;Vidovic et al 2013;Yokoyama et al 2011;Ziebell et al 2008a) The grouping of E. coli O157:H7 isolates into LSPA-6 subtypes has led to suggestions that lineage I isolates, which are those most likely to be associated with human illness, are more resistant to stresses such as heat and starvation, than those E. coli O157:H7 from lineage II which are less often associated with human illness (Lee et al 2012). There are also associations of LSPA-6 lineages and other typing methods such as SNP analysis, SBI, and stx subtypes, along with the presence or absence of specific gene markers (Wu et al 2008;Mellor et al 2012Yokoyama et al 2011;Stanton et al 2014).…”