Experimental models of subinhibitory disinfectant exposure and phenotypic adaptation in Listeria monocytogenes: A critical review

Listeria monocytogenes remains a major food-safety concern because its persistence in food-processing environments can promote exposure to subinhibitory disinfectant concentrations and phenotypic adaptation. We critically reviewed experimental evidence on the phenotypic effects of subinhibitory exposure of L. monocytogenes to benzalkonium chloride, peracetic acid, and sodium hypochlorite, placing particular emphasis on the exposure models and methodological choices that shape observed outcomes. A structured literature search was conducted in PubMed, Scopus, and Web of Science, and study selection was reported with PRISMA-style transparency. Twenty-one experimental studies with extractable quantitative outcomes were included in a structured comparative synthesis. Three main exposure models were identified: single, intermittent, and continuous exposure. Considerable variability was observed in exposure intensity, contact time, and strain selection. Most frequently assessed outcomes were changes in disinfectant susceptibility, biofilm-related phenotypes, cell-surface hydrophobicity, and antibiotic susceptibility. Overall, the literature indicates that subinhibitory exposure, particularly under repeated or sustained schemes, can be associated with increased tolerance to disinfectants and, in some cases, altered antibiotic susceptibility. However, conclusions are constrained by heterogeneous designs, limited reporting of key methodological elements, and simplified surface models (often not fully representative of food-processing conditions). We highlight key methodological sources of variability and priorities for more standardized, industry-relevant experimental designs.