|Rivera Betancourt, Mildred|
Submitted to: American Society of Microbiologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/4/2000
Publication Date: N/A
Technical Abstract: A study was conducted to determine if differences exist between phenotypically distinct strains of Escherichia coli O157:H7 during decontamination interventions on lean and adipose beef surfaces. Two strains were compared, namely, E. coli O157:H7 strains MA6 (rough phenotype) and ATCC 43895 (smooth phenotype). These pathogens were unable to ferment sorbitol and gave a negative MUG reaction. The virulence factors uidA, eaeA, hlyA, stx1, stx2, and rfbE were assessed for both pathogens by PCR and it was determined that MA6 did not possess the stx1 gene. Also, MA6 strain did not react with monoclonal antibody 13B3 (anti-O157). In a subsequent study, pre-rigor lean or adipose beef surfaces were inoculated with sterile bovine feces containing either E. coli O157:H7 MA6 or ATCC 43895 and spray washed with water, 2% acetic acid (AA), or 2% lactic acid (LA). Remaining bacterial populations were determined immediately after treatments. Of the interventions investigated, spray treatments with AA and LA were the most effective, regardless of the pathogen and tissue type. There were no statistical differences between the remaining bacterial populations for all the interventions investigated on lean tissue inoculated with E. coli O157:H7 MA6 or ATCC 43895. However, on adipose tissue, organic acids reduced E. coli O157:H7 MA6 to a greater extent than ATCC 43895. While tissue type may account for some of the observed differences in intervention effectiveness used in this study, strain's biochemical characteristics, including outer membrane composition and acid adaptation, may be factors that contribute to the results reported in this study.