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United States Department of Agriculture

Agricultural Research Service

Title: Optical Methods for Detecting E. Coli 0157:h7 Spiked on Cantaloupes

Authors
item Tu, Shu-I
item Uknalis, Joseph
item Gehring, Andrew

Submitted to: International Society for Optical Engineering
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2004
Publication Date: August 1, 2004
Citation: Tu, S., Uknalis, J., Gehring, A.G. 2004. Optical methods for detecting e. coli 0157:h7 spiked on cantaloupes. International Society for Optical Engineering. Paper No. 6-183.

Technical Abstract: Outbreaks of E. coli O157:H7 by the consumption of contaminated cantaloupes fruits have been documented. Pathogens harbored in the networked but porous veins in khaki colored skin are difficult to remove. Thus, sensitive and efficient methods are needed to detect the presence of E. coli O157:H7 in cantaloupes. In this work, known quantities of the E. coli were inoculated on cantaloupe skins at 4 degrees C for 24 h. The contaminated skin areas were sliced off and incubated in growth media at 37 degrees C for 6 h. The bacteria captured by magnetic beads coated with anti E. coli O157 antibodies were further sandwiched by second anti E. coli O157 antibodies containing either absorption (alkaline phosphatase) or fluorescence reporting (europium cation) functionality. The detected enzyme activity (catalyzed hydrolysis of phenyl phosphate) and time-delayed fluorescence (Eu extracted from the sandwiched E. coli O157 H7 complexes) were used to indicate the presence of the pathogen. The results indicated both the absorption and the fluorescence methods in 96 well microplate format could be applied to sensitively detect the E. coli contamination of cantaloupes.

Last Modified: 12/18/2014
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