|JADEJA, RAVIRAJSINH - University Of Georgia|
|HUNG, YEN-CON - University Of Georgia|
|Bosilevac, Joseph - Mick|
Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2012
Publication Date: 4/1/2013
Citation: Jadeja, R., Hung, Y., Bosilevac, J.M. 2013. Resistance of various shiga toxin-producing Escherichia coli to electrolyzed oxidizing water. Food Control. 30(2):580-584.
Interpretive Summary: Escherichia coli O157:H7 and six other non-O157 serotypes of Shiga toxin- producing E. coli (STEC) are considered adulterants in beef by the Food Safety Inspection Service. Therefore, interventions that reduce this group of E. coli are needed. A new intervention that can be used on beef is electrolyzed oxidizing (EO) water. EO water is made by passing electricity through a dilute salt solution, and contains chlorine and low pH that can kill E. coil. The effects of this water were tested on E. coli O157:H7, non-O157 STEC, plus E. coli O104 (from the 2011 German outbreak) and compared to sodium hypochlorite (a diluted bleach solution). EO water was more effective against all STEC compared to sodium hypochlorite. Further the tolerance of each STEC to EO water was measured and determined as E. coli O157> and equal to 103> and equal to O26> and equal to 0111> and equal to O121>and equal to 045>and equal to O145. Thus EO water can be used as an effective intervention to kill STEC and all the STEC examined were less tolerant than E. coli O157:H7.
Technical Abstract: 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 was tested against Electrolyzed oxidizing (EO) water using two different methods; modified AOAC 955.16 sequential inoculation method and minimum inhibitory concentration. In sequential inoculation method efficacy of sodium hypochlorite was also compared with equal free chlorine (45 mg/L) containing EO water. Minimum inhibitory experiments were conducted for 15s testing period with free chlorine concentrations of 3.00, 2.50, 2.00, 1.50, 1.00, 0.50 and 0.25 mg/L. The individual strain resistance when tested using the sequential inoculation method was in between 5 to 10 positive tubes, 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, 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 can equally if not more effectively reduce non-O157 STEC.