TY - JOUR
T1 - A novel selective medium for simultaneous enrichment of Shiga toxin–Producing Escherichia coli and salmonella in ground beef
AU - Eggers, Joseph
AU - Feirtag, Joellen M.
AU - Olstein, Alan D.
AU - Bosilevac, Joseph M.
N1 - Publisher Copyright:
© 2018 International Association for Food Protection. All rights reserved.
PY - 2018/8
Y1 - 2018/8
N2 - Microbiological analysis of ground beef for contamination by both Salmonella and Shiga toxin–producing Escherichia coli (STEC) is performed by the U.S. Department of Agriculture, Food Safety Inspection Service (FSIS), as part of its Performance Standards Verification Testing program. FSIS has established a zero tolerance for STEC serotype O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 because they are regarded as adulterants. The detection and isolation of these specific serogroups presents a technical challenge necessitating time-consuming and costly laboratory procedures that often exceed the technical capabilities of many small internal and reference laboratories. We describe here a method using a novel STEC and Salmonella selective (SSS) broth that allows for simultaneous selective enrichment of STEC and Salmonella sp., providing isolation and detection from the same broth. The method only involves direct plating from beef enrichments to detect suspect isolates that can be easily confirmed by using immunoassays or PCR, rendering the isolation simpler and less costly than the current described methods. In a side-by-side comparison with modified tryptic soy broth (mTSB), the use of SSS broth resulted in primarily isolating STEC and Salmonella sp., while substantially suppressing the growth of other gram-negative Enterobacteriacae by 90%. Significantly more (v2 , 3.84) samples containing E. coli O157:H7 and STEC O26, O111, O121, and O145 and a nondifferent (v2 . 3.84) number of samples containing STEC O103 and O45 were identified when enriching in SSS broth. Coenrichment using six different Salmonella serovars showed numerically greater but not significant (v2, 3.84) positive samples by using SSS broth compared with mTSB for a majority of serotypes.
AB - Microbiological analysis of ground beef for contamination by both Salmonella and Shiga toxin–producing Escherichia coli (STEC) is performed by the U.S. Department of Agriculture, Food Safety Inspection Service (FSIS), as part of its Performance Standards Verification Testing program. FSIS has established a zero tolerance for STEC serotype O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 because they are regarded as adulterants. The detection and isolation of these specific serogroups presents a technical challenge necessitating time-consuming and costly laboratory procedures that often exceed the technical capabilities of many small internal and reference laboratories. We describe here a method using a novel STEC and Salmonella selective (SSS) broth that allows for simultaneous selective enrichment of STEC and Salmonella sp., providing isolation and detection from the same broth. The method only involves direct plating from beef enrichments to detect suspect isolates that can be easily confirmed by using immunoassays or PCR, rendering the isolation simpler and less costly than the current described methods. In a side-by-side comparison with modified tryptic soy broth (mTSB), the use of SSS broth resulted in primarily isolating STEC and Salmonella sp., while substantially suppressing the growth of other gram-negative Enterobacteriacae by 90%. Significantly more (v2 , 3.84) samples containing E. coli O157:H7 and STEC O26, O111, O121, and O145 and a nondifferent (v2 . 3.84) number of samples containing STEC O103 and O45 were identified when enriching in SSS broth. Coenrichment using six different Salmonella serovars showed numerically greater but not significant (v2, 3.84) positive samples by using SSS broth compared with mTSB for a majority of serotypes.
KW - Food safety
KW - Pathogenic Escherichia coli
KW - Salmonella
KW - Shiga toxin–producing Escherichia coli isolation
UR - http://www.scopus.com/inward/record.url?scp=85051068100&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85051068100&partnerID=8YFLogxK
U2 - 10.4315/0362-028X.JFP-17-520
DO - 10.4315/0362-028X.JFP-17-520
M3 - Article
C2 - 29979615
AN - SCOPUS:85051068100
SN - 0362-028X
VL - 81
SP - 1252
EP - 1257
JO - Journal of food protection
JF - Journal of food protection
IS - 8
ER -