Detection of E. coli O157:H7 in raw ground beef by Pathatrix™ immunomagnetic-separation, real-time PCR and cultural methods

被引:48
作者
Fedio, Willis M. [1 ]
Jinneman, Karen C. [2 ]
Yoshitomi, Ken J. [2 ]
Zapata, Ruben
Wendakoon, Chitra N.
Browning, Paul
Weagant, Stephen D. [2 ]
机构
[1] New Mexico State Univ, Food Safety Lab, Ctr Anim Hlth Food Safety & Biosecur, Las Cruces, NM 88003 USA
[2] US FDA, Bothell, WA USA
关键词
Pathogen detection; Real-time PCR; Immunomagnetic separation; ESCHERICHIA-COLI; HEMORRHAGIC COLITIS; SEROTYPE O157-H7; RAPID ISOLATION; ENRICHMENT; FOODS; IDENTIFICATION; EPIDEMIOLOGY; SPROUTS; PRODUCE;
D O I
10.1016/j.ijfoodmicro.2011.05.005
中图分类号
TS2 [食品工业];
学科分类号
0832 ;
摘要
Detection of Escherichia coli O157:H7 by conventional cultural methods can be difficult in food matrices with a high background flora such as raw ground beef. Raw ground beef samples, artificially contaminated separately with five strains of E. coli O157:H7 at low (similar to 0.2 cfu/g) and high (similar to 2 cfu/g) levels, were enriched by two enrichment protocols; buffered peptone water (BPW) at 37 C for 5 h and 24 h and modified buffered peptone water with pyruvate (mBPWp) for 5 h at 37 degrees C followed by adding selective agents and incubating at 42 degrees C to 24 h. Detection of added E. coli O157:H7 by real-time PCR (RTiPCR) and recovery on isolation agars was performed before and after PATHATRIX (TM) immunomagnetic separation (IMS). RTiPCR detection and cultural recovery of inoculated E. coli O157:H7 after 5 h enrichment were poor at 0.21-0.24 cfu/g. The addition of IMS after 5 h enrichment did not improve RTiPCR detection but markedly improved recovery by culturing. By extending enrichment to 24 h, RTiPCR detection improved to 76% for either enrichment protocol without IMS. When 24 h enrichment was followed by IMS, RTiPCR detection was also further improved. Cultural recovery after 24 h enrichment was 56% and 84% without IMS and 100% and 92% after IMS for BPW and mBPWp respectively. Extended enrichment to 24 h followed by IMS was found to be sensitive and reliable for detection and cultural recovery from raw ground beef using either enrichment method. (C) 2011 Elsevier B.V. All rights reserved.
引用
收藏
页码:87 / 92
页数:6
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