Resistance of Listeria monocytogenes, Escherichia coli O157:H7 and Campylobacter jejuni after exposure to repetitive cycles of mild bactericidal treatments

• Published in: Food microbiology Vol. 26; no. 8; pp. 889 - 895
• Main Authors: Rajkovic, Andreja, Smigic, Nada, Uyttendaele, Mieke, Medic, Helga, de Zutter, Lieven, Devlieghere, Frank
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-12-2009
• Subjects: adaptation; Adaptation, Physiological; antimicrobial agents; bacterial contamination; Campylobacter jejuni; Campylobacter jejuni - drug effects; Campylobacter jejuni - physiology; Campylobacter jejuni - radiation effects; chemical treatment; Chlorine Compounds - pharmacology; chlorine dioxide; Colony Count, Microbial; Consumer Product Safety; decontamination; defense mechanisms; disinfectants; Disinfectants - pharmacology; disinfection; dosage; Drug Resistance, Bacterial; Escherichia coli; Escherichia coli O157 - drug effects; Escherichia coli O157 - physiology; Escherichia coli O157 - radiation effects; Escherichia coli O157:H7; Food Irradiation; Food Microbiology; food pathogens; Food Preservation - methods; inactivation; Increased resistance; intense light pulses; lactic acid; Lactic Acid - pharmacology; light; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - physiology; Listeria monocytogenes - radiation effects; microbial growth; Mild bactericidal treatments; minimally processed foods; Oxides - pharmacology; pathogen survival; risk assessment; Species Specificity; Listeria monocytogenes; Mild bactericidal treatments; Escherichia coli O157:H7; Increased resistance; Campylobacter jejuni
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2009.06.006

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.