Antimicrobial-resistant Enterobacter cloacae complex strains isolated from fresh vegetables intended for raw consumption and their farm environments in the Northwest of Spain

Antimicrobial resistance is a global concern with significant public health implications. We investigated the role of fresh vegetables and their cultivation environments as reservoirs for antimicrobial-resistant Enterobacter cloacae complex (ECC) strains. The study focused on AmpC-producing ECC isolates and their resistance to colistin, a last resort antibiotic.AmpC-producing ECC isolates were detected and confirmed in 10.2% of the 235 samples examined, with no significant difference (p > 0.05) in prevalence between farm and street market samples. Further analysis of 24 AmpC-ECC isolates revealed that 16.7% exhibited resistance to colistin.A colistin-resistant E. kobei strain (AG07E) was detected in irrigation water from a vegetable farm for the first time in Spain. This strain carried the mcr-9.1 gene, demonstrating transferability. It was included in ST56 which is predominantly reported in clinical E. kobei harbouring the mcr-9 gene. Additionally, we identified a multidrug-resistant E. kobei strain (ZA03E) from carrot samples, exhibiting colistin resistance and potential human pathogenicity. This strain belonged to ST125 which has clonal relationships with strains in ST56.Our findings emphasise the importance of monitoring and addressing antimicrobial-resistant ECC strains in fresh vegetables and their production environments, particularly the water, to mitigate potential risks to public health from a One Health perspective.