title: Gene expression in Listeria monocytogenes exposed to sublethal concentration of benzalkonium chloride.
abstract: In this study, tolerance at sublethal concentration of benzalkonium chloride and transcription levels of mdrL, ladR, lde, sigB and bcrABC genes in Listeria monocytogenes strains were evaluated. Viable cells reduction occurred in 45% of strains and clinical isolates showed lower sensitivity than isolates from foods. An increased transcription of an efflux system encoding gene was found in 60% of strains, and simultaneous mdrL overexpression and ladR underexpression occurred in 30% of isolates. A significant association between reduced benzalkonium chloride activity and both mdrL and sigB overexpression was observed; sigB expression also correlated with both mdrL and ladR genes. The bcrABC gene was only found in six strains, all isolated from foods and sensitive to benzalkonium chloride, and in four strains an underexpression was observed. Disinfection at sublethal concentration was less effective in clinical isolates, and mdrL and sigB expression was significantly affected by disinfection. Further insights are needed to understand the adaptation to benzalkonium chloride and to evaluate whether changes in gene expression could affect the L. monocytogenes virulence traits and persistence in the environment.
authors.affiliation: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy. Electronic address: manuela.tamburro@unimol.it.
authors.forename: Manuela
authors.initials: M
authors.lastname: Tamburro
authors.affiliation: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy. Electronic address: ripab@unimol.it.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ripabelli
authors.affiliation: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy. Electronic address: monia.vitullo@unimol.it.
authors.forename: Monia
authors.initials: M
authors.lastname: Vitullo
authors.affiliation: Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK. Electronic address: Tim.Dallman@phe.gov.uk.
authors.forename: Timothy James
authors.initials: TJ
authors.lastname: Dallman
authors.affiliation: Department of Health Sciences, University of Milan, Milan, Italy. Electronic address: mirella.pontello@unimi.it.
authors.forename: Mirella
authors.initials: M
authors.lastname: Pontello
authors.affiliation: Gastrointestinal Bacteria Reference Unit, Public Health England, London, UK. Electronic address: Corinne.Amar@phe.gov.uk.
authors.forename: Corinne Francoise Laurence
authors.initials: CF
authors.lastname: Amar
authors.affiliation: Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy. Electronic address: sammarco@unimol.it.
authors.forename: Michela Lucia
authors.initials: ML
authors.lastname: Sammarco
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D004203:Disinfection; D004361:Drug Tolerance; D005516:Food Microbiology; D015870:Gene Expression; D019450:Genes, MDR / Q000187:drug effects; D007558:Italy; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D008088:Listeriosis / Q000382:microbiology; D050296:Microbial Viability / Q000187:drug effects; D010641:Phenotype; D012808:Sigma Factor / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D001548:Benzalkonium Compounds; C480945:SigB protein, Listeria monocytogenes; D012808:Sigma Factor
keywords: Benzalkonium chloride; Cross-response; Efflux systems; Gene expression; Listeria monocytogenes