The present work addresses the effect of excess levels of ZnCl₂ and CuSO₄ in the growth medium on the conjugative transfer of plasmids carrying the antibiotic resistance gene bla_CMY-2 from extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. Norwegian poultry are not treated prophylactically with antibiotics, but still, ESBL-producing E. coli are found in the chicken populations. Chickens receive higher amounts of Zn and Cu than their biological need, and several metals have been shown to act as drivers of antimicrobial resistance. In the present study, ESBL-producing E. coli strains collected from retail chicken meat were mated in broth containing various concentrations of ZnCl₂ and CuSO₄. Manual counting of transconjugants showed that ZnCl₂ and CuSO₄ reduced the conjugation frequency between E. coli strains in a concentration-dependent manner. Quantitative real-time PCR analyses showed that the presence of ZnCl₂ and CuSO₄ in the growth media reduced expression of the conjugation genes traB and nikB. By propagating monocultures over several generations, it was found that the bla_CMY-2 plasmids remained stable in the recipient strains. Together the results show that exposure of ESBL-producing E. coli to Zn and Cu reduce horizontal transfer of the bla_CMY-2 resistance plasmid by reducing expression of genes involved in conjugation in the plasmid donor strain.

中文翻译：

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锌和铜减少了产生广谱β-内酰胺酶的大肠杆菌的抗性质粒的共轭转移。

目前的工作解决了生长培养基中过量的ZnCl ₂和CuSO ₄对携带抗生素抗性基因bla _CMY-2的质粒从生产广谱β-内酰胺酶（ESBL）的大肠杆菌中共轭转移的影响。挪威家禽未经过抗生素预防性治疗，但仍在鸡群中发现了产生ESBL的大肠杆菌。鸡收到的锌和铜的含量超过了他们的生物学需要，而且几种金属已被证明可作为抗药性的驱动力。在本研究中，产生ESBL的大肠杆菌从零售鸡肉中收集的菌株交配到含有各种浓度的ZnCl ₂和CuSO _4的肉汤中。手工计数转导结合物表明，ZnCl ₂和CuSO ₄以浓度依赖的方式降低了大肠杆菌菌株之间的结合频率。实时定量PCR分析表明，生长培养基中ZnCl ₂和CuSO ₄的存在会降低缀合基因traB和nikB的表达。通过传播单一世代数代，我们发现bla _CMY-2质粒在受体菌株中保持稳定。在一起的结果表明，通过减少质粒供体菌株中参与缀合的基因的表达，将产生ESBL的大肠杆菌暴露于Zn和Cu会降低bla _CMY-2抗性质粒的水平转移。