Validation of three rapid screening methods for detection of verotoxin-producing Escherichia coli in foods: interlaboratory study.
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.
Capps
Katherine L
KL
Central Science Laboratory, Sand Hutton, York, North Yorkshire, YO41 1LZ, United Kingdom.
McLaughlin
Emiline M
EM
Murray
Alistair W A
AW
Aldus
Clare F
CF
Wyatt
Gary M
GM
Peck
Michael W
MW
van Amerongen
Aart
A
Ariëns
Renata M C
RM
Wichers
Jan H
JH
Baylis
Christopher L
CL
Wareing
David R A
DR
Bolton
Frederick J
FJ
D000818:Animals; D001628:Beverages / Q000032:analysis; D015169:Colony Count, Microbial; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000737:chemistry* / Q000378:metabolism*; D019453:Escherichia coli O157 / Q000737:chemistry; D005516:Food Microbiology; D007118:Immunoassay; D027845:Malus / Q000737:chemistry; D008460:Meat / Q000032:analysis / Q000382:microbiology; D008892:Milk / Q000737:chemistry / Q000382:microbiology; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D022603:Shiga Toxins / Q000032:analysis* / Q000096:biosynthesis*
D022603:Shiga Toxins