The threat represented by antibiotic resistance is more and more requiring the identifi cation of alternative methods to manage infections exerted by pathogens such as Escherichia coli K88, the main determining agent of piglets’ post-weaning diarrhea. Pharmacological levels of zinc oxide are usually employed for their capacity to improve growth performance and intestinal integrity at weaning. However, the environmental pollution exerted by ZnO is raising concerns. Considering future legislative requirements, which will forbid the usage of zinc for pharmacological purposes, this study evaluated the antimicrobial activity of conventional antibiotics and several zinc forms, and their ability to modulate the E. coli K88 virulence gene expression. Results demonstrate how the E. coli K88 tested strain is resistant to most of the tested antibiotics; amongst zinc forms, only ZnO, nano-ZnO, ZnSO4 and Zn-Met show an antimicrobial activity at 2000 ppm. ZnO, nano-ZnO, ZnSO4 and ZnCl2 – at doses providing 65 ppm of Zn – increased 145the expression of E. coli K88 virulence factors. In conclusion, this study demonstrated the capacity of pharmacological doses of various Zn forms to exert an antimicrobial effect only at 2000 ppm, while their utilization at nutritional levels produces a signifi cant modulation of virulence genes of E. coli K88.
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Discover More: Bonetti et al. (2021). XLVI meeting annuale Società Italiana di Patologia ed Allevamento dei Suini (SIPAS)