title: Resistance of Listeria monocytogenes, Escherichia coli O157:H7 and Campylobacter jejuni after exposure to repetitive cycles of mild bactericidal treatments.
abstract: While maintaining nutritional and sensorial attributes of fresh foods mild processing technologies generally deliver microbiologically perishable food products. Currently little information exists on possible increase in the resistance of pathogens after repetitive exposure to mild (sub-lethal) treatments. Multiple strain-cocktails of Listeria monocytogenes, Escherichia coli O157:H7 and Campylobacter jejuni were exposed to 20 consecutive cycles of sub-lethal inactivation by three different techniques. Used techniques comprised inactivation with lactic acid (LA), chlorine dioxide (ClO(2)) and intense light pulses (ILP). Results showed that the selection of resistant cells was both species and technique dependent. While repetitive cycles of ClO(2) treatment did not result in increased resistance, repetitive inactivation with LA yielded L. monocytogenes culture of higher resistance in comparison to the parental culture. The increased resistance, expressed as decreased level of reduction in bacterial counts in subsequent inactivation cycles, was also observed with ILP for both L. monocytogenes and E. coli O157:H7 strains. Visual trend observations were confirmed through statistical linear regression analysis. No such effects were noted for C. jejuni which became undetectable after first 2-5 cycles. Current findings indicate the ability of foodborne pathogens to adapt to mild bactericidal treatments creating new challenges in risk assessment and more specifically in hazard analysis.
authors.affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
authors.forename: Andreja
authors.initials: A
authors.lastname: Rajkovic
authors.forename: Nada
authors.initials: N
authors.lastname: Smigic
authors.forename: Mieke
authors.initials: M
authors.lastname: Uyttendaele
authors.forename: Helga
authors.initials: H
authors.lastname: Medic
authors.forename: Lieven
authors.initials: L
authors.lastname: de Zutter
authors.forename: Frank
authors.initials: F
authors.lastname: Devlieghere
mesh_terms: D000222:Adaptation, Physiological; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects; D017606:Chlorine Compounds / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004202:Disinfectants / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects; D005514:Food Irradiation; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D019344:Lactic Acid / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D010087:Oxides / Q000494:pharmacology; D013045:Species Specificity
chemical_list: D017606:Chlorine Compounds; D004202:Disinfectants; D010087:Oxides; D019344:Lactic Acid; C025109:chlorine dioxide