Abstract
Extra-intestinal E. coli are emerging as a global threat due to their diffusion as opportunistic pathogens and, above all, to their wide set of antibiotic resistance determinants. There are still many gaps in our knowledge of their origin and spread pathways, although food animals have been adjudicated vehicles for passing mult-drug resistant bacteria to humans. This study analyzed 46 samples of meat purchased from retail stores in Palermo in order to obtain quinolone-resistant E. coli isolates. Strains were screened for their phylogenetic groups, ST131-associated single nucleotide polymorphisms (SNPs), and then typed by ERIC-PCR. Their set of virulence factors, namely, kpsMII, papA, sfaS, focG, iutA, papC, hlyD, and afa genes, were investigated and their fluoroquinolone-resistance determinants evaluated. The data obtained show a dramatically high prevalence of multidrug resistance patterns in the Palermo area, with 28% of the isolates having virulence factor genes typical of ExPEC strains. No B2 group or ST131 strains were detected. Moreover, 20% of our isolates showed positivity to all the plasmid-mediated quinolone resistance (PMQR) determinants, showing a potential to transfer these genes among other bacteria. Therefore, these data underline the possibility that food animals and, specifically, poultry in particular may be a significant source of resistant bacterial strains, posing a potential zoonotic risk.
Highlights
The outburst of the antibiotic resistance phenomenon at global level has occurred due to the excessive and inappropriate use of antimicrobials in various fields, both in human medicine and in veterinary and zootechnical settings, strongly accelerating the development and diffusion of resistant strains
The steady increase in the prevalence of quinolone-resistant Extra-intestinal Pathogenic E. coli (ExPEC) isolates is alarming due to their spread as opportunistic pathogens and suggests the need to deepen our knowledge of their source, reservoirs, and transmission pathways
Poultry meat was highly contaminated with E. coli resistant to quinolones (91.3% of samples)
Summary
The outburst of the antibiotic resistance phenomenon at global level has occurred due to the excessive and inappropriate use of antimicrobials in various fields, both in human medicine and in veterinary and zootechnical settings, strongly accelerating the development and diffusion of resistant strains. Commensal enteric bacteria are exposed to this wide variety of antimicrobial substances, leading to an increase in resistance genes and, potentially, their horizontal transfer. These bacteria may function as a reservoir of resistance though largely ignored [7]. ST131 isolates are commonly reported to harbour a wide variety of virulence-associated genes, including a greater ability to produce biofilms compared to non-ST131 isolates [15]. Due to these features, ST131 strains are considered to be truly pathogenic [13]. The aim of this study, was to assess the prevalence of multidrug resistant E. coli with ExPECassociated traits in food that could pose a risk for consumers
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