Chemical and bio-hazard assessment of swine manure valorisation: antibiotic and antibiotic-resistant bacteria screening.

Swine manure management poses significant environmental and economic challenges, mainly due to the contribution of traditional practices resulting in antibiotic soil contamination and the spread of antibiotic-resistant bacteria. This research aims to comprehensively characterize swine manure physicochemical and resistome phenotype profiles (including minimum inhibitory concentrations) from several locations with different farm management techniques, providing the foundation for more sustainable and effective treatment strategies The analyses revealed the presence of a wide range of antimicrobial compounds, including amoxicillin, ciprofloxacin, erythromycin, oxytetracycline, tetracycline, sulfamethoxazole and trimethoprim, with concentrations ranging from 7.2 to 5395 µg/kg of dry weight of swine manure. A total of 73 antibiotic-resistant bacteria were isolated, 44 % of which exhibited resistance to three or more antibiotics, i.e., were multidrug resistant bacteria. The highest resistance frequencies were observed against the sulfamethoxazole/trimethoprim combination (62 %), erythromycin (55 %), and amoxicillin (52 %), whereas oxytetracycline (7 %) had the lowest resistance incidence. Notably, several of the environmental strains identified, such as Psychrobacter spp., Denicitrifimonas spp., Brevundimonas spp., Achromobacter spp., and Glutamicibacter spp., have not previously been reported as antibiotic-resistant or multidrug-resistant, highlighting emerging risks within the microbial community associated with swine manure.