Variation in Resistance of Natural Isolates of Escherichia coli O157 to High Hydrostatic Pressure, Mild Heat, and Other Stresses

AUTOR(ES)

Benito, Amparo

FONTE

American Society for Microbiology

RESUMO

Strains of Escherichia coli O157 isolated from patients with clinical cases of food-borne illness and other sources exhibited wide differences in resistance to high hydrostatic pressure. The most pressure-resistant strains were also more resistant to mild heat than other strains. Strain C9490, a representative pressure-resistant strain, was also more resistant to acid, oxidative, and osmotic stresses than the pressure-sensitive strain NCTC 12079. Most of these differences in resistance were observed only in stationary-phase cells, the only exception being acid resistance, where differences were also apparent in the exponential phase. Membrane damage in pressure-treated cells was revealed by increased uptake of the fluorescent dyes ethidium bromide and propidium iodide. When strains were exposed to the same pressure for different lengths of time, the pressure-sensitive strains took up stain sooner than the more resistant strain, which suggested that the differences in resistance may be related to susceptibility to membrane damage. Our results emphasize the importance of including stress-resistant strains of E. coli O157 when the efficacy of a novel or mild food preservation treatment is tested.

Documentos Relacionados

• Variation in Resistance to High Hydrostatic Pressure and rpoS Heterogeneity in Natural Isolates of Escherichia coli O157:H7
• Heat Shock Protein-Mediated Resistance to High Hydrostatic Pressure in Escherichia coli
• Antibody Responses to Escherichia coli O157 and Other Lipopolysaccharides in Healthy Children and Adults
• Enhanced Acid Sensitivity of Pressure-Damaged Escherichia coli O157 Cells
• Escherichia coli O157 and Non-O157 Isolates Are More Susceptible to l-Lactate than to d-Lactate