sodium-hypochlorite and fumaric-acid

In the years after the discovery of this pathogen, Escherichia coli O157:H7 has become increasingly prominent, and outbreaks have been reported in many areas.. In the current study, we determined the expressions of virulent factor genes shiga-like toxin II (stxII) and E. coli attaching and effacing (eaeA), in strains that were isolated from cattle feces and a clinical case in Taiwan. In addition, the effects of chemical and low-temperature stresses and adaptions on the expressions of virulent factor genes were investigated. Furthermore, the outer membrane proteins of acid-adapted E. coli O157:H7 TWC01 (TWC01) was separated using two-dimensional electrophoresis, and proteins were identified using mass spectrometry in order to illustrate the changes in protein expression after adaption.. Expressions of stxII and eaeA in the TWC01 isolated from a clinical case were higher than those in two strains isolated from cattle feces, and both organic and inorganic acid stresses and adaptions enhance the expression of genes encoding virulent factors in strains. In addition, the outer membrane proteins of TWC01 were regulated under hydrochloric acid adaption, indicating induction of acid tolerance and enhancement adhesion in TWC01. Lactic acid treatment of TWC01 resulted in downregulation of channel protein and adherence-related protein expressions.. The results of this study are helpful in understanding the resistance of locally isolated TWC01 to chemical and low-temperature stresses, and improving the control of this pathogen.

Topics: Adhesins, Bacterial; Animals; Bacterial Outer Membrane Proteins; Cattle; Cold Temperature; Electrophoresis, Gel, Two-Dimensional; Escherichia coli O157; Escherichia coli Proteins; Feces; Fumarates; Humans; Hydrochloric Acid; Lactic Acid; Shiga Toxin 2; Sodium Hypochlorite; Virulence Factors

The effect of the disinfectant sodium hypochlorite (NaClO), with or without mild heat (50 degrees C) and fumaric acid, on native bacteria and the foodborne pathogens Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella Typhimurium DT104 attached to iceberg lettuce leaves was examined. The retail lettuce examined consistently harbored 6 to 7 log CFU/g of native bacteria throughout the study period. Inner leaves supported 1 to 2 log CFU/g fewer bacteria than outer leaves. About 70% of the native bacterial flora was removed by washing five times with 0.85% NaCl. S. aureus, E. coli, and Salmonella allowed to attach to lettuce leaves for 5 min were more easily removed by washing than when allowed to attach for 1 h or 2 days, with more S. aureus being removed than E. coli or Salmonella Typhimurium. An increase of time for attachment of pathogens from 5 min to 2 days leads to decreased efficiency of the washing and sanitizing treatment. Treatment with fumaric acid (50 mM for 10 min at room temperature) was the most effective, although it caused browning of the lettuce, with up to a 2-log reduction observed. The combination of 200 ppm of sodium hypochlorite and mild heat treatment at 50 degrees C for 1 min reduced the pathogen populations by 94 to 98% (1.2- to 1.7-log reduction) without increasing browning.

Topics: Bacterial Adhesion; Colony Count, Microbial; Consumer Product Safety; Disinfectants; Dose-Response Relationship, Drug; Drug Synergism; Escherichia coli O157; Fumarates; Humans; Lactuca; Salmonella typhimurium; Sodium Hypochlorite; Staphylococcus aureus; Temperature; Time Factors