Resistance beyond the plate: heavy metal, disinfectant, and antibiotic resistance in foodborne <i>Staphylococcus aureus</i> isolates

Staphylococcus aureus is a major foodborne pathogen capable of developing resistance to multiple antimicrobial agents, including antibiotics, disinfectants, and heavy metals. This study investigated 63 S. aureus isolates recovered from poultry products, meat cuts, and processed or ready-to-eat foods for their resistance to selected disinfectants [benzalkonium chloride (BC), cetylpyridinium chloride (CPC), triclosan (TCS)] and heavy metals [zinc (Zn), nickel (Ni), mercury (Hg), copper (Cu), cadmium (Cd), lead (Pb), cobalt (Co)]. The isolates from processed and ready-to-eat foods exhibited significantly higher resistance scores to antibiotics, disinfectants, and heavy metals compared to those from meat and poultry (P < .001). Notably, 45% of isolates from processed foods were resistant to 8 out of 10 tested agents, and enterotoxigenic isolates displayed significantly elevated resistance profiles across all tested agent classes (antibiotics, heavy metals, disinfectants) (U = 99.0, P < .001). These findings highlight the potential role of food processing environments in selecting for multidrug-resistant and virulent S. aureus strains. The co-occurrence of resistance to antibiotics, disinfectants, and heavy metals suggests the involvement of co-selection mechanisms, emphasizing the need for integrated surveillance, and targeted interventions to reduce the spread of resistant pathogens in the food chain.