title: Effects of osmotic pressure, acid, or cold stresses on antibiotic susceptibility of Listeria monocytogenes.
abstract: Prevalence of antibiotic resistance of Listeria monocytogenes isolated from a variety of foods has increased in many countries. L. monocytogenes has many physiological adaptations that enable survival under a wide range of environmental stresses. The objective of this study was to evaluate effects of osmotic (2, 4, 6, 12% NaC), pH (6, 5.5, 5.0) and cold (4 °C) stresses on susceptibility of three isolates of L. monocytogenes towards different antibiotics. The minimal inhibitory concentrations (MICs) of tested antibiotics against unstressed (control), stressed or post-stressed L. monocytogenes isolates (an ATCC strain and a meat and dairy isolate) were determined using the broth microdilution method. Unstressed cells of L. monocytogenes were sensitive to all tested antibiotics. In general, when L. monocytogenes cells were exposed to salt, cold and pH stresses, their antibiotic resistance increased as salt concentration increased to 6 or 12%, as pH was reduced to pH 5 or as temperature was decreased to 10 °C. Results showed that both meat and dairy isolates were more resistant than the ATCC reference strain. Use of sub-lethal stresses in food preservation systems may stimulate antibiotic resistance responses in L. monocytogenes strains.
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan. Electronic address: anas_nabulsi@just.edu.jo.
authors.forename: Anas A
authors.initials: AA
authors.lastname: Al-Nabulsi
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan.
authors.forename: Tareq M
authors.initials: TM
authors.lastname: Osaili
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan.
authors.forename: Reyad R
authors.initials: RR
authors.lastname: Shaker
authors.affiliation: Department of Food Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Amin N
authors.initials: AN
authors.lastname: Olaimat
authors.affiliation: Department of Biological and Genetic Engineering, Jordan University of Science and Technology, Irbid, Jordan.
authors.forename: Ziad W
authors.initials: ZW
authors.lastname: Jaradat
authors.affiliation: Department of Nutrition and Food Technology, Jordan University of Science and Technology, Irbid, Jordan.
authors.forename: Noor A
authors.initials: NA
authors.lastname: Zain Elabedeen
authors.affiliation: Department of Food Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Holley
mesh_terms: D000143:Acids / Q000494:pharmacology*; D000222:Adaptation, Physiological; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003080:Cold Temperature; D024881:Drug Resistance, Bacterial; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000502:physiology*; D009997:Osmotic Pressure
chemical_list: D000143:Acids; D000900:Anti-Bacterial Agents
keywords: Acid stress; Antibiotic susceptibility; Cold stress; Listeria monocytogenes; Osmotic pressure; Stress adaptation