• Home
  • Search Results
  • Effects of osmotic pressure, acid, or cold stresses on antibiotic susceptibility of Listeria monocytogenes.

Effects of osmotic pressure, acid, or cold stresses on antibiotic susceptibility of Listeria monocytogenes.

Food microbiology (2014-12-06)
Anas A Al-Nabulsi, Tareq M Osaili, Reyad R Shaker, Amin N Olaimat, Ziad W Jaradat, Noor A Zain Elabedeen, Richard A Holley
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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Potassium phosphate tribasic, reagent grade, ≥98%
Sigma-Aldrich
Lactic acid solution, ACS reagent, ≥85%
Sigma-Aldrich
DL-Lactic acid, ~90% (T)
Sigma-Aldrich
Lactic acid, 85%, FCC
Sigma-Aldrich
Trichostatin A, ≥98% (HPLC), from Streptomyces sp.
Sigma-Aldrich
Lactic acid, meets USP testing specifications
Sigma-Aldrich
Lactic acid, natural, ≥85%
Supelco
Lactic acid, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
DL-Lactic acid, 85 % (w/w), syrup
USP
Lactic acid, United States Pharmacopeia (USP) Reference Standard