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Automated imunomagnetic separation for the detection of Escherichia coli O157:H7 from spinach
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Escherichia coli O157:H7 is a major cause of foodborne illness and methods for rapid and sensitive detection of this deadly pathogen are needed to protect consumers. The use of immunomagnetic separation (IMS) for capturing and detecting foodborne pathogens has gained popularity, partially due to the introduction of automated and high throughput IMS instrumentation. Three methods for automated IMS that test different sample volumes, Kingfisher® mL, Pathatrix® Auto, and Pathatrix® Ultra, were compared using microbiological detection of E. coli O157:H7 from buffered peptone water (BPW), in the presence of background microbial flora derived from spinach leaves, and from culture enrichments from artificially contaminated spinach leaves. The average efficiencies of capture of E. coli O157:H7 using the three methods were 32.1%, 3.7%, and 1.3%, respectively, in BPW; 43.4%, 8.8%, 2.9%, respectively, in the presence of spinachmicrobial flora; and 63.0%, 7.0%, and 6.3%,respectively, from artificially contaminated spinach. Despite the large differences in IMS capture efficiencies between the KingFisher® and two Pathatrix® methods, all three methods allowed the detection of E. coli O157:H7 from spinach that was artificially contaminated with the pathogen at relatively high (25 cfu/30 g sample) and low (1 cfu/30 g sample) levels after 4–6 h of culture enrichment. The differences in capture efficiencywere compensated for by the differences in sample volume used by the KingFisher® mL (1 mL), Pathatrix® Auto (50 mL) and Pathatrix® Ultra (250 mL) instruments. Thus, despite the reduced capture efficiencies observed for the Pathatrix® methods, the large increase in sample volume results in a greater number of captured cells for downstream detection resulting in improved detection sensitivity.
Andrew G. Gehring
George C. Paoli
Escherichia coli O157
USDA Scientist Submission
International journal of food microbiology 2014 v.179
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Agricultural Research Service
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