Neglected Drivers of Antibiotic Resistance: Survival of Extended-Spectrum ß-Lactamase-Producing Pathogenic Escherichia coli from Livestock Waste through Dormancy and Release of Transformable Extracellular Antibiotic Resistance Genes under Heat Treatment.

ABSTRACT

Extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae has caused a global pandemic with high prevalence in livestock and poultry, which could disseminate into the environment and humans. To curb this risk, heat-based harmless treatment of livestock waste was carried out. However, some risks of the bacterial persistence have not been thoroughly assessed. This study demonstrated that antibiotic-resistant bacteria (ARB) could survive at 55 °C through dormancy, and simultaneously transformable extracellular antibiotic resistance genes (eARGs) would be released. The ESBL-producing pathogenic Escherichia coli CM1 from chicken manure could enter a dormant state at 55 °C and reactivate at 37 °C. Dormant CM1 had stronger ß-lactam resistance, which was associated with high expression of ß-lactamase genes and low expression of outer membrane porin genes. Resuscitated CM1 maintained its virulence expression and multidrug resistance and even had stronger cephalosporin resistance, which might be due to the ultra-low expression of the porin genes. Besides, heat at 55 °C promoted the release of eARGs, some of which possessed a certain nuclease stability and heat persistence, and even maintained their transformability to an Acinetobacter baylyi strain. Therefore, dormant multidrug-resistant pathogens from livestock waste will still pose a direct health risk to humans, while the resuscitation of dormant ARB and the transformation of released eARGs will jointly promote the proliferation of ARGs and the spread of antibiotic resistance.