Benzalkonium chloride (BAC) is a quaternary ammonium disinfectant widely applied in food processing and environmental sanitation. Repeated exposure to sub-inhibitory residue levels of BAC induces adaptive responses in foodborne pathogens and reshapes their virulence phenotype across multiple aspects. Existing studies indicate that BAC-adapted strains exhibit diverse alterations in key virulence traits, including biofilm formation, toxin production, hemolytic activity, adhesiveness, invasiveness, and host lethality, most of which are enhanced to varying extents. These phenotypic shifts are underpinned by multi-layered mechanisms, such as modulation of virulence gene expression, genetic mutations and horizontal gene transfer, remodeling of membrane composition, activation of efflux pumps, enhancement of quorum-sensing signals, and induction of viable but non-culturable states. Such adaptive responses not only enhance bacterial persistence along the food chain but also potentially elevate pathogenicity in hosts, posing potential food safety risks. This paper systematically summarizes the correlation between BAC adaptation and changes in typical virulence factors of foodborne pathogens. It helps to reveal the evolutionary patterns of pathogen virulence driven by disinfectant residues, providing a theoretical basis and technical references for optimizing disinfectant usage strategies, developing targeted inhibitors, and improving microbial risk assessment frameworks.

Benzalkonium chloride is a quaternary ammonium compound with bactericidal activity, which is widely used in domestic and healthcare settings as well as in food processing environments. It plays an important role in the prevention and control of foodborne pathogens. However, the presence of biofilms or improper use of benzalkonium chloride may enable foodborne pathogens to adapt to bactericides, affecting the tolerance to homologous or heterologous biocidal agents. The review summarizes the relationship between the adaptation of foodborne pathogens to benzalkonium chloride and their tolerance to this biocide. The reasons for the increased tolerance to benzalkonium chloride are explained from the perspectives of the expression of efflux pump genes, cell membrane modification, and the formation of the viable but non-cultivable (VBNC) state. Furthermore, the influence of benzalkonium chloride adaptation on the antibiotic resistance of foodborne pathogens is discussed, and the reasons for the increased antibiotic resistance are summarized from the perspectives of biofilm formation, spontaneous mutations, horizontal gene transfer, and the role of efflux pumps in antibiotic resistance. This review could help understand the mechanism of the adaption of foodborne pathogens to benzalkonium chloride and provide a reference for the rational use of biocides and the prevention and control of foodborne pathogens.