When Disinfection Fails: Biocide Tolerance as a Driver of Campylobacter Persistence and Resistance

Campylobacter spp. constitutes a significant global public health hazard as it is a leading cause of reported foodborne diseases. Human infection is predominantly acquired through the ingestion of contaminated food, unpasteurized milk and untreated water, prompting the widespread implementation of chemical disinfection across several sectors, from healthcare, domestic environments, and food-processing to animal husbandry. While these biocidal agents encompass multiples classes with different modes of action and efficacy, growing evidence suggests that their extensive and repeated use may unintentionally promote bacterial persistence, tolerance and adaptive responses. Although biocide resistance has been documented in several foodborne pathogens, data on biocide tolerance in Campylobacter spp. remain limited. Available studies report variable degrees of reduced susceptibility to commonly used biocides among isolates originating from poultry production, food-processing environments, and water systems. Importantly, while biocide-induced adaptive responses in Campylobacter spp. may potentially overlap with antimicrobial resistance mechanisms, the extent to which these agents drive co-selection, persistence, or dissemination requires further elucidation. Evidence remains limited on the effects of long-term and repeated exposure under realistic processing conditions, the interplay between stress-induced gene regulation and stable genetic changes, and the contribution of mobile genetic elements, biofilm formation, and microbial communities in shaping antimicrobial resistance evolution. In light of the global health burden imposed by campylobacteriosis and the rising challenge of antimicrobial-resistant Campylobacter, this review brings together current evidence on the role of biocides in shaping bacterial survival, adaptation, and resistance mechanisms.