Validation of three rapid screening methods for detection of verotoxin-producing Escherichia coli in foods: interlaboratory study

• Published in: Journal of AOAC International Vol. 87; no. 1; pp. 68 - 77
• Main Authors: Capps, K.L, McLaughlin, E.M, Murray, A.W.A, Aldus, C.F, Wyatt, G.M, Peck, M.W, Amerongen, A. van, Ariens, R.M.C, Wichers, J.H, Baylis, C.L
• Format: Journal Article
• Language: English
• Published: England 01.01.2004
• Subjects: Animals; apple cider; bacterial contamination; Beverages - analysis; Colony Count, Microbial; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Escherichia coli - chemistry; Escherichia coli - metabolism; Escherichia coli O157 - chemistry; Escherichia coli O157:H7; food contamination; Food Microbiology; genes; ground beef; Immunoassay; immunoassays; lateral flow immunoassay; Malus - chemistry; Meat - analysis; Meat - microbiology; Milk - chemistry; Milk - microbiology; polymerase chain reaction; raw milk; Reproducibility of Results; Reverse Transcriptase Polymerase Chain Reaction; salami; Shiga Toxins - analysis; Shiga Toxins - biosynthesis; verotoxins
• ISSN: 1060-3271; 1944-7922
• DOI: 10.1093/jaoac/87.1.68

An interlaboratory study was conducted for the validation of 3 methods for the detection of all verotoxin-producing Escherichia coli (VTEC) in foods. The methods were a multi-analyte 1-step lateral flow immunoassay (LFIA) for detection of E. coli O157 and verotoxin (VT); an enzyme-linked immunosorbent assay targeted against VT1, VT2, and VT2c (VT-ELISA); and a polymerase chain reaction (PCR) method for detection of VT genes (VT-PCR). Aliquots (25 g or 25 mL) of 4 food types (raw minced [ground] beef, unpasteurized milk, unpasteurized apple juice [cider], and salami) were individually inoculated with low numbers (<9 to 375 cells/25 g) of 6 test strains of E. coli (serogroups O26, O103, O111, O145, and O157) with differing VT-producing capabilities. Five replicates for each test strain and 5 uninoculated samples were prepared for each food type. Fourteen participating laboratories analyzed samples using the LFIA, 9 analyzed the samples by ELISA, and 9 by PCR. The LFIA for O157 and VT had a specificity (correct identification of negative samples) of 92 and 94%, respectively, and a sensitivity (correct identification of positive samples) of 94 and 55%, respectively. The VT-ELISA and VT-PCR had a specificity of 98 and 99%, respectively, and a sensitivity of 89 and 72%, respectively.