Sublethal concentrations of heavy metals Cu<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e781" altimg="si5.svg"><mml:msup><mml:mrow /><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> and Zn<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="d1e791" altimg="si5.svg"><mml:msup><mml:mrow /><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math> can induce the emergence of bacterial …

The emergence of multidrug resistance has become an environmental safety issue worldwide concern. Numerous studies have confirmed that heavy metals can promote the spread bacterial resistance. However, in addition to co-resistance plasmids, role and mechanism at sublethal levels (< minimum inhibitory concentration [MIC]) on antibiotic remain poorly defined. Here we investigated alteration phenotype under Cu2+ Zn2+ exposure explored molecular by which affect results showed MIC Escherichia coli Staphylococcus aureus antibiotics, especially norfloxacin tetracyclines, was significantly increased after seven consecutive days exhibited a higher cross-resistance rate, meant induce bacteria develop resistances were not previously available. It observed downregulation outer membrane protein gene ompC metal exposure, while expression other efflux pump genes E. upregulated, tetB, tolC arcAB genes, suggesting might enhance altering genes. Moreover, many point mutations found system resistant mutant strains. In particular, quinolone-resistant strains mutation conversion serine (Ser) phenylalanine (Phe) residue 464 gyrB gene, may also be important cause quinolone This study provides explanation for effect