Prevalence of Virulence Determinants and Antimicrobial Resistance among Commensal Escherichia coli Derived from Dairy and Beef Cattle

Abstract

Cattle is a reservoir of potentially pathogenic E. coli, bacteria that can represent a significant threat to public health, hence it is crucial to monitor the prevalence of the genetic determinants of virulence and antimicrobial resistance among the E. coli population. The aim of this study was the analysis of the phylogenetic structure, distribution of virulence factors (VFs) and prevalence of antimicrobial resistance among E. coli isolated from two groups of healthy cattle: 50 cows housed in the conventional barn (147 isolates) and 42 cows living on the ecological pasture (118 isolates). The phylogenetic analysis, identification of VFs and antimicrobial resistance genes were based on either multiplex or simplex PCR. The antimicrobial susceptibilities of E. coli were examined using the broth microdilution method. Two statistical approaches were used to analyse the results obtained for two groups of cattle. The relations between the dependent (VFs profiles, antibiotics) and the independent variables were described using the two models. The mixed logit model was used to characterise the prevalence of the analysed factors in the sets of isolates. The univariate logistic regression model was used to characterise the prevalence of these factors in particular animals. Given each model, the odds ratio (OR) and the 95% confidence interval for the population were estimated. The phylogroup B1 was predominant among isolates from beef cattle, while the phylogroups A, B1 and D occurred with equal frequency among isolates from dairy cattle. The frequency of VFs-positive isolates was significantly higher among isolates from beef cattle. E. coli from dairy cattle revealed significantly higher resistance to antibiotics. Some of the tested resistance genes were present among isolates from dairy cattle. Our study showed that the habitat and diet may affect the genetic diversity of commensal E. coli in the cattle. The results suggest that the ecological pasture habitat is related to the increased spreading rate of the VFs, while the barn habitat is characterised by the higher levels of antimicrobial resistance among E. coli.

Large-scale genome analysis of bovine commensal Escherichia coli reveals that bovine-adapted E. coli lineages are serving as evolutionary sources of the emergence of human intestinal pathogenic strains

“…1). These findings are basically concordant with the previous finding that most bovine commensal isolates belonged to phylogroups B1 and A (Bok et al 2015;Madoshi et al 2016;Mercat et al 2016). As for human commensal isolates, it was reported that B2 strains predominate in people residing in developed countries in the temperate regions of the world (Escobar-Paramo et al 2004;Skurnik et al 2008).…”

Comparison by multilocus variable-number tandem repeat analysis and antimicrobial resistance among atypical enteropathogenicEscherichia colistrains isolated from food samples and human and animal faecal specimens

“…Phylogenetic Groups B1 and D, and virulence Group Ia were specific among patients and cattle strains in Cluster 2, which confirmed the results of our previous study (Wang et al 2013). Bok et al (2015) also observed that the phylogenetic Group B1 was predominant among isolates from beef cattle; similarly, an Australian survey (Staples et al 2013) reported that the majority of EPEC strains fell into Group B1. Together, these findings suggested that cattle are a major source of strains that are diarrhoeagenic in humans, particularly for strains of Group B1.…”

“…Bok et al . () also observed that the phylogenetic Group B1 was predominant among isolates from beef cattle; similarly, an Australian survey (Staples et al . ) reported that the majority of EPEC strains fell into Group B1.…”

Prevalence and distribution of antimicrobial resistance determinants ofEscherichia coliisolates obtained from meat in South Africa

“…The results observed in this study are in agreement with studies done in Ethiopia, Iran, and Pakistan [41–44]. Meanwhile, our findings contradict findings of earlier studies done in South Africa and Poland that reported lower prevalences [25,29].…”

“…The other reason could be the co-selection of resistant determinant and co-resistance of the E. coli isolates. The simultaneous resistance to penicillin, streptomycin, tetracycline, erythromycin, kanamycin, and virginiamycin has been reported in studies conducted elsewhere [29–31]. A similar co-selection of sulphonamide resistance genes was reported in chickens treated with streptomycin [32].…”