Electrolyzed water for inactivation of shiga toxin-producing Escherichia coli

Summary

Electrolyzed oxidizing water (EO) is one of the emerging environment friendly antimicrobial treatments. EO water has been successfully used to control Salmonella, Listeria monocytogenies and E. coli O157:H7 on various vegetables, fish and seafoods, poultry and eggs. EO water could be an answer to the need for new effective interventions in beef processing. In order to maximize antimicrobial intervention's efficiency and minimize the complexity involved in testing individual STEC, it is important to understand which serotype is the most resistant to EO water treatment so if a proposed intervention can successfully reduce the level of most resistant STEC then it can be assured that other STEC are also eliminated.

Situation

Non-O157 shiga toxin producing Escherichia coli (STEC) are one of the most important emerging groups of food borne pathogens in the recent times. It has been estimated that non-O157 STEC causes approximately 112,752 cases of foodborne illness in the United States annually. The true number of illnesses caused by non-O157 STEC may be underestimated however, as only about 4% of clinical laboratories reported routinely screening for these pathogens. Illnesses caused by STEC exhibit symptoms ranging from mild diarrhea to hemolytic uremic syndrome (HUS) and kidney failure. There are over 100 disease causing non-O157 STEC have been identified from clinical samples worldwide but in the USA six major STEC serogroups: O26, O45, O103, O121, O111 and O145 are responsible for 71% of non-O157 STEC illnesses. Cattle have been implicated as the primary reservoir of STEC and contamination of any beef product with feces is often attributed STEC infection. Because of risks associated with consumption of contaminated beef, the U.S. Department of Agriculture Food Safety and Inspection Service has recently added six major non-O157 STEC (O26, O45, O103, O121, O111 and O145) in addition to O157:H7 as adulterants in some beef products. Hence, it is important for beef producers to review their current pathogen mitigation strategies and new intervention steps on their efficacy to inactivate both E. coli O157:H7 and non-O157 STEC.

Response

The resistance of thirty two strains of Escherichia coli O157:H7 and six major serotypes of non-O157 shiga toxin-producing E. coli (STEC) plus E. coli O104:H4 was tested against electrolyzed oxidizing (EO) water using two different methods; modified AOAC 955.16 sequential inoculation method and minimum inhibitory concentration (MIC). The individual strain resistance when tested using the sequential inoculation method was in between 5 to 10 positive tubes, where greater numbers of positive tubes indicate increased resistance of the respective strain to the particular sanitizer. The MIC of individual strains ranged from 0.50 to 1.50 mg/L free chlorine of EO water. In comparison to sodium hypochlorite at same free chlorine concentration EO water was more effective against all STEC cocktails tested. The resistance of STEC cocktails using sequential inoculation method was determined as E. coli O157= O103= O26= 0111= O121= 045> O145. The similar pattern of resistance was observed when cocktails were subjected to MIC. The results indicate that different strains of same serotype can differ in their resistance toward an intervention. In addition, EO water treatment that reduces E. coli O157:H7 can equally if not more effectively reduce other non-O157 STEC tested.

Impact

This research demonstrates the potential of EO water for inactivation of shiga toxin-producing Escherichia coli. An Industry Advisory Board was established including Cargill Beef, JBS USA Beef, White Oak Pastures, Kraft Foods, Bubba Foods, EAU Technologies (EO water generator manufacturer), KES Science (TiO2-UV coating technologies), Publix, Whole Foods, Southeastern Meat Association, and USDA-FSIS to make sure this research is addressing the industry needs.

State Issue

Food Safety

Details

• Year: 2012
• Geographic Scope: International
• County: Spalding
• Program Areas:
  • Agriculture & Natural Resources