Salad Vegetables as a Reservoir of Antimicrobial-Resistant : Exploring Diversity, Resistome, Virulence, and Plasmid Dynamics.

This study investigates the occurrence, antimicrobial resistance (AMR) profiles, virulence factors, and plasmid composition of species isolated from salad ingredients in the United Arab Emirates (UAE). Four hundred salad vegetable items collected from local markets, over ten months through 2023, were screened, yielding an detection rate of 85.5% (342/400). was the most commonly identified species (50%), followed by (20%) and (16%). Among 85 isolates tested for antimicrobial susceptibility, 55.3% displayed resistance to at least one agent, with 18.8% classified as multidrug-resistant (MDR). All isolates were not resistant to ampicillin, linezolid, teicoplanin, tigecycline, and high-level gentamicin. Intrinsic phenotypic resistance to vancomycin was found in and , while low-level (<5%) ciprofloxacin and erythromycin resistance was sporadically detected in and . Whole-genome sequencing (WGS) of 14 isolates (nine , four , and one ) unveiled a complex resistome. We report the first detection in salad vegetables of vancomycin resistance genes (, ) in a vancomycin-susceptible isolate. Identifying , , and genes in the studied isolates further underscored emerging resistance to tetracyclines, macrolides, and oxazolidinones. Concurrently, virulence gene analysis revealed 74 putative virulence factors, with harboring a higher diversity of biofilm-related and exoenzyme-encoding genes. One strain carried the cytolysin cluster (, , ), highlighting its pathogenic potential. Plasmid profiling identified 19 distinct plasmids, ranging from 3845 bp to 133,159 bp. Among the genome-sequenced isolates, mobilizable plasmids (47.3%) commonly carried AMR genes, especially () and (), whereas conjugative plasmids (10.5%) did not harbor resistance determinants. These findings highlight that salad vegetables can still harbor and potentially transmit strains with clinically relevant resistance determinants and virulence traits. Enhancing foodborne AMR surveillance with WGS and targeted interventions is key to controlling its spread in the food.