Location: Meat Safety and QualityTitle: Evaluation of GENE-UP® new markers EHEC for detection of Shiga Toxin-producing Escherichia coli in MicroTally sheets collected from beef carcasses
|LIU, TIANQING - Colorado State University|
|Bosilevac, Joseph - Mick|
|JIA, MO - Colorado State University|
|GEORNARAS, IFIGENIA - Colorado State University|
|DUTTA, VIKRANT - Biomerieux, Inc|
|BELK, KEITH - Colorado State University|
|YANG, HUA - Colorado State University|
Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2020
Publication Date: 8/2/2020
Citation: Liu, T., Bosilevac, J.M., Wheeler, T.L., Arthur, T.M., Jia, M., Geornaras, I., Dutta, V., Belk, K.E., Yang, H. 2020. Evaluation of GENE-UP® new markers EHEC for detection of Shiga Toxin-producing Escherichia coli in MicroTally sheets collected from beef carcasses. [Abstract]. International Association for Food Protection, Cleveland Ohio, August 2-5, 2020, Virtual. Journal of Food Protection. 83(Supplement 1):P2-70.
Technical Abstract: Introduction: Detection of Shiga toxin-producing Escherichia coli (STEC) based on the stx, eae and Top7 serogroup-associated genes may result in false positives. The GENE-UP® New Markers EHEC kit is designed to target virulence genes (espK, espV and CRISPR_O26E) for more accurate screening of pathogenic STEC. Purpose: To evaluate the GENE-UP® New Markers EHEC (NM-EHEC) kit using a selected panel of STEC strains and E.coli-inoculated MicroTally sheets (MT). Methods: A total of 96 STEC strains from diverse origins, including feces, beef products and carcasses, ground beef and humans, were used to evaluate the NM-EHEC kit. These strains were also tested for virulence factors, including ecf1, stx, espk1, nleB, eae, nleF, subAB and ehxA genes. In addition, 144 beef carcasses were sampled with individual MT, and these, in turn, were either inoculated with selected E.coli strains or were left uninoculated. All samples were enriched (42°C, 10 h) in 200 mL of buffered peptone water and then tested using GENE-UP® kits (NM-EHEC, STEC stx/eae [EH1], STEC-Top 6 [EH2], and E. coli O157:H7 [ECO]) following the manufacturer’s instructions. Presumptive positives were plated onto ChromIDTM Coli and CHROMagar STEC plates for cultural confirmation. Results: The NM-EHEC kit results for the 96 STEC strains corresponded 100% with the virulence profiles of the strains. For the 144 MT samples evaluated, 55 positives were obtained with EH1, 49 positives with both EH1 and NM-EHEC, and 43 presumptive positives with a combination of EH1, NM-EHEC, EH2 and ECO. Among the 43 presumptive positives, 41 were confirmed as true positives by culture and two were a false positives. Therefore, the positive predictive value for NM-EHEC was 95.3%. Significance: The GENE-UP® New Markers EHEC kit can be used to screen for pathogenic STEC that are more relevant to public health and therefore, reduce presumptive positives that require cultural confirmation.