Multiple antibiotic-resistant extra-intestinal pathogenic Escherichia coli (ExPEC) strains represent a serious health care problem both for poultry and humans. Recently isolates with combined resistance to both antibiotics and heavy metals have been increased worldwide, with growing concern for possible co-selection of antimicrobial resistant genes. In the present study we characterized, at a phenotypic and genetic level, 80 E. coli isolates: forty independent isolates were collected from manure samples of healthy chickens and 40 from independent human extra-intestinal infections (ExPEC strains). The results obtained indicated that i) compared to chicken, human isolates presented a broader spectrum of antibiotic resistance and virulence potentials; ii) although at a lower extent, ExPEC-associated virulence genes were also present in chicken isolates, suggesting they may be potentially pathogens; iii) that arsenic (As) and zinc (Zn) tolerance genetic determinants were significantly more prevalent among chicken and human isolates respectively, while those responsible for tolerance to cadmium (Cd), silver (Ag) and copper (Cu) were equally distributed among the two groups of strains; iv) a very strong correlation was found between chicken gentamicin (GM) resistance and cadmium (Cd) tolerance. Elucidating the role of heavy metals in the selection and spread of highly pathogenic E. coli strains (co-selection) is of primary importance to lower the potential risk of infections in poultry and humans. The control of bacterial zoonotic agents, that commonly occur in livestock and that may be transmitted, directly or via the food chain, to human populations, could be of relevant interest.

多重抗药性肠外致病性大肠埃希菌（ExPEC）菌株代表了家禽和人类严重的医疗保健问题。最近，在世界范围内已经增加了对抗生素和重金属的综合耐药性的分离株，人们越来越担心可能会共同选择抗菌素耐药基因。在本研究中，我们在表型和遗传水平上鉴定了80种大肠杆菌分离株：从健康鸡粪样品中收集了40个独立的分离株，并从独立的人肠外感染（ExPEC菌株）中分离了40个。获得的结果表明：i）与鸡相比，人类分离株具有更广泛的抗生素抗性和毒力潜力；ii）尽管在较低水平上，鸡分离物中也存在与ExPEC相关的毒力基因，表明它们可能是潜在的病原体；iii）耐砷（As）和耐锌（Zn）的遗传决定因素分别在鸡和人分离株中更为普遍，而对镉（Cd），银（Ag）和铜（Cu）的耐性负责的因素在两组菌株；iv）发现鸡肉庆大霉素（GM）耐药性与镉（Cd）耐受性之间存在很强的相关性。阐明重金属在高致病性的选择和传播中的作用大肠杆菌菌株（共选择）对于降低家禽和人类感染的潜在风险至关重要。普遍存在于牲畜中并且可能直接或通过食物链传播给人类的细菌人畜共患病菌的控制可能引起人们的关注。