scholarly journals Immunomagnetic separation and size-based detection of Escherichia coli O157 at the meniscus of a membrane strip

RSC Advances ◽  
2018 ◽  
Vol 8 (46) ◽  
pp. 26266-26270 ◽  
Author(s):  
Hyeonjeong Lee ◽  
Jeongin Hwang ◽  
Yunsung Park ◽  
Donghoon Kwon ◽  
Sanghee Lee ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Flow Velocity ◽  
Test Strip ◽  
Immunomagnetic Separation ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Membrane Strip

E. coli–Au/MNC complexes accumulate at the meniscus of the test strip where the flow velocity reaches a maximum.

An Aggregation-Induced Emission Material Labeling Antigen-Based Lateral Flow Immunoassay Strip for Rapid Detection of Escherichia coli O157:H7

2021 ◽  
pp. 247263032098193
Author(s):  
Cheng Liu ◽  
Shuiqin Fang ◽  
Yachen Tian ◽  
Youxue Wu ◽  
Meijiao Wu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rapid Detection ◽  
Foodborne Pathogen ◽  
Test Strip ◽  
Lateral Flow ◽  
Detection Sensitivity ◽  
Lateral Flow Immunoassay ◽  
Escherichia Coli O157 ◽  
Aggregation Induced Emission ◽  
E Coli

Escherichia coli O157:H7 ( E. coli O157:H7) is a dangerous foodborne pathogen, mainly found in beef, milk, fruits, and their products, causing harm to human health or even death. Therefore, the detection of E. coli O157:H7 in food is particularly important. In this paper, we report a lateral flow immunoassay strip (LFIS) based on aggregation-induced emission (AIE) material labeling antigen as a fluorescent probe for the rapid detection of E. coli O157:H7. The detection sensitivity of the strip is 105 CFU/mL, which is 10 times higher than that of the colloidal gold test strip. This method has good specificity and stability and can be used to detect about 250 CFU of E. coli O157:H7 successfully in 25 g or 25 mL of beef, jelly, and milk. AIE-LFIS might be valuable in monitoring food pathogens for rapid detection.

Comparison of Rapid Enzyme-Linked Immunosorbent Assay and Immunomagnetic Separation Methods for Detection of Escherichia coli O157 in Fecal, Hide, Carcass, and Ground Beef Samples

2007 ◽  
Vol 70 (10) ◽  
pp. 2230-2234 ◽  
Author(s):  
T. W. THOMPSON ◽  
T. P. STEPHENS ◽  
G. H. LONERAGAN ◽  
M. F. MILLER ◽  
M. M. BRASHEARS
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Immunomagnetic Separation ◽  
Separation Method ◽  
Enzyme Linked Immunosorbent Assay ◽  
Escherichia Coli O157 ◽  
Perfect Agreement ◽  
Fecal Samples ◽  
E Coli ◽  
Beef Products

Rapid enzyme-linked immunosorbent assays (ELISAs) are approved for detection of Escherichia coli O157 in beef products. However, these kits have also been used in the industry to detect this pathogen on hides or in feces of cattle, although this use has not been validated. The objective of this study was to compare commercially available ELISAs (E. coli Now, Reveal, and VIP) with immunomagnetic separation along with selective media to detect E. coli O157 on hides, in feces, and in medium- and low-level-inoculated ground beef and carcasses (simulated by using briskets) samples. Naturally infected hide and fecal samples were subjected to both the immunomagnetic separation method and ELISAs for the detection of E. coli O157. Additionally, E. coli O157 inoculated and noninoculated ground beef and beef briskets were used to simulate meat and carcass samples. When comparing the detection results from the ELISAs (E. coli Now, Reveal, and VIP) to the immunomagnetic separation method, poor agreement was observed for fecal samples (kappa = 0.10, 0.02, and 0.03 for E. coli Now, Reveal, and VIP, respectively), and fair-to-moderate agreement was observed for hide samples (kappa = 0.30, 0.51, and 0.29 for E. coli Now, Reveal, and VIP, respectively). However, there was near-perfect agreement between the immunomagnetic separation method and ELISAs for ground beef (kappa = 1, 1, and 0.80 for E. coli Now, Reveal, and VIP, respectively) and brisket (kappa = 1, 1, and 1 for E. coli Now, Reveal, and VIP, respectively) samples. Assuming immunomagnetic separation is the best available method, these data suggest that the ELISAs are not useful in detecting E. coli O157 from hide or fecal samples. However, when ELISAs are used on ground beef and beef brisket samples they can be used with a high degree of confidence.

Modeling of the Effect of Washing Solution Flow Conditions on Escherichia coli O157:H7 Population Reduction on Fruit Surfaces

2007 ◽  
Vol 70 (11) ◽  
pp. 2533-2540 ◽  
Author(s):  
HUA WANG ◽  
WEI LIANG ◽  
HAO FENG ◽  
YAGUANG LUO
Keyword(s):  
Escherichia Coli ◽  
Flow Velocity ◽  
Reduction Rate ◽  
Escherichia Coli O157 ◽  
Agitation Rate ◽  
Flow Conditions ◽  
Solution Flow ◽  
E Coli ◽  
Pathogen Reduction ◽  
Over The Top

Washing produce with sanitizing solutions is an important step in reducing microbial populations during postharvest handling. Little information exists regarding the effects of washing solution flow conditions on the efficacy of pathogen reduction during washing. This study was undertaken to investigate the effects of washing conditions such as flow velocity, agitation rate, and contact time on the reduction of Escherichia coli O157:H7 populations from the surfaces of cantaloupe rind and cut apples. Top surfaces of cylindrical samples were spot inoculated with E. coli O157:H7 and treated with peroxyacetic acid (POAA; 80 mg/liter) solution under different flow velocities and agitation rates and with different washing modes. Test results indicate that the reduction rate of E. coli O157:H7 increased with the increase in flow velocity and agitation rate under the testing conditions. In a 3-min treatment in the flow-through chamber, the E. coli O157:H7 count reduction on cantaloupe rind and cup apples reached 2.5 and 2.3 log CFU/cm2, respectively, when the flow velocity increased from 0.0 to 0.8 m/min. Agitation conducted at the bottom of the treatment chamber reduced the E. coli O157:H7 population on cut apples by 1.2 log CFU/cm2 in 3 min, whereas in the treatment with the agitation over the top of the chamber, the survival count of E. coli O157:H7 was reduced by only 0.8 log CFU/cm2. The experimental data were used to fit four microbial reduction kinetic models. It was found that E. coli O157:H7 reduction from the fruit surfaces was best described by the Weibull model. These findings may be useful in designing produce wash systems for achieving enhanced pathogen reduction and improved produce quality and safety.

scholarly journals Development and Characterization of a Fluorescent-Bacteriophage Assay for Detection of Escherichia coli O157:H7

1999 ◽  
Vol 65 (4) ◽  
pp. 1397-1404 ◽  
Author(s):  
Lawrence Goodridge ◽  
Jinru Chen ◽  
Mansel Griffiths
Keyword(s):  
Escherichia Coli ◽  
Flow Cytometry ◽  
Immunomagnetic Separation ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Lower Detection ◽  
Unreliable Method ◽  
Direct Epifluorescent Filter Technique ◽  
Bacterial Concentrations

ABSTRACT In this paper we describe evaluation and characterization of a novel assay that combines immunomagnetic separation and a fluorescently stained bacteriophage for detection of Escherichia coliO157:H7 in broth. When it was combined with flow cytometry, the fluorescent-bacteriophage assay (FBA) was capable of detecting 104 cells/ml. A modified direct epifluorescent-filter technique (DEFT) was employed in an attempt to estimate bacterial concentrations. Using regression analysis, we calculated that the lower detection limit was between 102 and 103cells/ml; however, the modified DEFT was found to be an unreliable method for determining bacterial concentrations. The results of this study show that the FBA, when combined with flow cytometry, is a sensitive technique for presumptive detection of E. coliO157:H7 in broth cultures.

Virulence Characterization and Molecular Subtyping of Typical and Atypical Escherichia coli O157:H7 and O157:H(−) Isolated from Fecal Samples and Beef Carcasses in Mexico

2015 ◽  
Vol 78 (2) ◽  
pp. 264-272 ◽  
Author(s):  
CLAUDIA NARVÁEZ-BRAVO ◽  
ALEJANDRO ECHEVERRY ◽  
MARKUS F. MILLER ◽  
ARGENIS RODAS-GONZÁLEZ ◽  
M. TODD BRASHEARS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Genes ◽  
Immunomagnetic Separation ◽  
Latex Agglutination ◽  
Escherichia Coli O157 ◽  
High Genetic Diversity ◽  
E Coli ◽  
System A ◽  
Metabolic Genes ◽  
Beef Carcasses

The objective of the study was to characterize virulence genes and subtype Escherichia coli O157:H7 and O157:H(−) isolates obtained from a vertically integrated feedlot slaughter plant in Mexico. A total of 1,695 samples were collected from feedlots, holding pens, colon contents, hides, and carcasses. E. coli O157:H7 detection and confirmation was carried out using conventional microbiology techniques, immunomagnetic separation, latex agglutination, and the BAX system. A total of 97 E. coli O157 strains were recovered and screened for key virulence and metabolic genes using multiplex and conventional PCR. Eighty-eight (91.72%) of the strains carried stx2, eae, and ehxA genes. Ten isolates (8.25%) were atypical sorbitol-fermenting strains, and nine were negative for the flicH7 gene and lacked eae, stx1, stx2, and ehxA. One sorbitol-positive strain carried stx2, eae, tir, toxB, and iha genes but was negative for stx1 and ehxA. Pulsed-field gel electrophoresis (PFGE) analysis yielded 49 different PFGE subtypes, showing a high genetic diversity; however, the majority of the typical isolates were closely related (80 to 90% cutoff). Atypical O157 isolates were not closely related within them or to typical E. coli O157:H7 isolates. Identical PFGE subtypes were found in samples obtained from colon contents, feedlots, holding pens, and carcasses. Isolation of a sorbitol-fermenting E. coli O157 positive for a number of virulence genes is a novel finding in Mexico. These data showed that genetically similar strains of E. coli O157:H7 can be found at various stages of beef production and highlights the importance of preventing cross-contamination at the pre- and postharvest stages of processing.

Relative Sensitivity of Escherichia coli O157 Detection from Bovine Feces and Rectoanal Mucosal Swabs

2014 ◽  
Vol 77 (6) ◽  
pp. 972-976 ◽  
Author(s):  
K. J. WILLIAMS ◽  
M. P. WARD ◽  
O. DHUNGYEL ◽  
L. VAN BREDA
Keyword(s):  
Escherichia Coli ◽  
Confidence Interval ◽  
Human Health Risk ◽  
Relative Sensitivity ◽  
Immunomagnetic Separation ◽  
Detection Methods ◽  
Escherichia Coli O157 ◽  
Prevalence Studies ◽  
E Coli ◽  
The Difference

The need to quantify the potential human health risk posed by the bovine reservoir of Escherichia coli O157 has led to a wealth of prevalence studies and improvements in detection methods over the last two decades. Rectoanal mucosal swabs have been used for the detection of E. coli O157 fecal shedding, colonized animals, and those predisposed to super shedding. We conducted a longitudinal study to compare the detection of E. coli O157 from feces and rectoanal mucosal swabs (RAMS) from a cohort of dairy heifers. We collected 820 samples that were tested by immunomagnetic separation of both feces and RAMS. Of these, 132 were detected as positive for E. coli O157 from both samples, 66 were detected as positive from RAMS only, and 117 were detected as positive from feces only. The difference in results between the two sample types was statistically significant (P < 0.001). The relative sensitivities of detection by immunomagnetic separation were 53% (confidence interval, 46.6 to 59.3) from RAMS and 67% (confidence interval, 59.6 to 73.1) from fecal samples. No association between long-term shedding (P = 0.685) or super shedding (P = 0.526) and detection by RAMS only was observed.

Pulsed-Field Gel Electrophoresis Characterization of Shiga Toxin–Producing Escherichia coli O157 from Hides of Cattle at Slaughter

2002 ◽  
Vol 65 (7) ◽  
pp. 1172-1176 ◽  
Author(s):  
S. M. AVERY ◽  
A. SMALL ◽  
C.-A. REID ◽  
S. BUNCIC
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gel Electrophoresis ◽  
Immunomagnetic Separation ◽  
Pulsed Field Gel Electrophoresis ◽  
Escherichia Coli O157 ◽  
Adult Cattle ◽  
Pulsed Field ◽  
E Coli ◽  
High Prevalence

Contamination of the brisket areas of the hides of healthy adult cattle with Shiga toxin–producing Escherichia coli O157 at slaughter in England was studied. In total, 73 cattle consignments comprising 584 animals delivered to one abattoir over 3 days during 1 week in July 2001 were studied: 26 cattle consignments arriving on Monday, 32 consignments arriving on Wednesday, and 15 consignments arriving on Friday. Consignment sizes ranged from 1 to 23 animals, with a mean consignment size of 8. The hide of the first animal to be slaughtered in each consignment was sampled by using a sponge swab moistened with 0.85% saline to rub an unmeasured brisket (ventral) area (ca. 30 by 30 cm). The process of isolating E. coli O157 from the swabs consisted of enrichment, screening with immunoprecipitation assay kits, and immunomagnetic separation. E. coli O157 was found on 24 of 73 (32.9%) cattle hides examined, and 21 of these 24 isolates produced Shiga toxins. The 24 E. coli O157 isolates produced six different pulsed-field gel electrophoresis profiles, and 18 (75%) of the isolates were of one prevalent clone. The high prevalence of one E. coli O157 clone on the hides of cattle at slaughter could be due to a high prevalence of that clone on the 18 farms involved (not investigated in the current study), in the postfarm transport or lairage environments, or both. Since the lairage environment, but not the farm of origin or the postfarm transport vehicle, was a factor common to all 18 cattle consignments, it could have played an important role in spreading the prevalent E. coli O157 clone to the cattle hides. Lairage pen floors and the stunning box floor were identified as the most probable sites along the unloading-to-slaughter route at which the brisket areas of cattle hides could become contaminated.

Prevalence and Numbers of Escherichia coli O157 on Bovine Hides at a Beef Slaughter Plant

2005 ◽  
Vol 68 (4) ◽  
pp. 660-665 ◽  
Author(s):  
S. B. O[apos]BRIEN ◽  
G. DUFFY ◽  
E. CARNEY ◽  
J. J. SHERIDAN ◽  
D. A. McDOWELL ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Early Stage ◽  
Immunomagnetic Separation ◽  
Pcr Analysis ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Hemolysin Gene ◽  
Peptone Water ◽  
Encoding Gene ◽  
Genetic Profiles

In this study, we investigated the prevalence and numbers of Escherichia coli O157 on bovine hides. Samples (n = 1,500) were collected over a 17-month period (30 samples per week) by sponge swabbing approximately 122-cm2 areas of the bovine rump of slaughtered cattle at an early stage of carcass processing (first legging). Sponge samples (n = 1,500) were stomached in buffered peptone water supplemented with novobiocin, directly plated on sorbitol MacConkey with Cefixime tellurite (SMAC-CT), enriched for 24 h, extracted by immunomagnetic separation, and plated onto SMAC-CT agar. Presumptive E. coli O157 colonies from SMAC-CT plates were confirmed by PCR for the presence of eaeA, hlyA, fliCh7, vt1, vt2, and portions of the rfb (O-antigen encoding) region of E. coli O157. Overall, E. coli O157 was recovered from 109 samples (7.3%) at concentrations ranging from less than 0.13 to 4.24 log CFU/100 cm2. PCR analysis revealed a wide diversity of genetic profiles among recovered isolates of verocytotoxigenic E. coli. Of the isolates recovered, 99 of 109 contained the attaching and effacing gene (eaeA) and the hemolysin gene (hlyA), and 78 of 109 had the flagellar H7 antigen–encoding gene (fliCh7). Only 6 of 109 isolates contained both verotoxin-producing genes (vt1 and vt2); 91 of 109 contained the vt2 gene only, whereas 1 of 109 contained the vt1 gene only. The remaining 11 of 109 contained neither vt1 nor vt2.

An Investigation of Escherichia coli O157 Contamination of Cattle during Slaughter at an Abattoir

2005 ◽  
Vol 68 (3) ◽  
pp. 451-457 ◽  
Author(s):  
NARELLE FEGAN ◽  
GLEN HIGGS ◽  
PAUL VANDERLINDE ◽  
PATRICIA DESMARCHELIER
Keyword(s):  
Escherichia Coli ◽  
Oral Cavity ◽  
Immunomagnetic Separation ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Probable Number ◽  
Fecal Samples ◽  
E Coli ◽  
Cell Counts ◽  
Carcass Contamination

The extent of contamination with Escherichia coli O157 was determined for 100 cattle during slaughter. Samples from 25 consecutively slaughtered cattle from four unrelated groups were collected from the oral cavity, hide, rumen, feces after evisceration, and pre- and postchill carcass. Ten random fecal samples were collected from the pen where each group of animals was held at the abattoir. E. coli O157 was detected using automated immunomagnetic separation (AIMS), and cell counts were determined using a combination of most probable number (MPN) and AIMS. E. coli O157 was isolated from 87 (14%) of the 606 samples collected, including 24% of 99 oral cavity samples, 44% of 100 hides, 10% of 68 fecal samples collected postevisceration, 6% of 100 prechill carcass swabs, and 15% of 40 fecal samples collected from holding pens. E. coli O157 was not isolated from rumen or postchill carcass samples. E. coli O157 was isolated from at least one sample from each group of cattle tested, and the prevalence in different groups ranged from less than 1 to 41%. The numbers of E. coli O157 differed among the animals groups. The group which contained the highest fecal (7.5 × 105 MPN/g) and hide (22 MPN/cm2) counts in any individual animal was the only group in which E. coli O157 was isolated from carcasses, suggesting a link between the numbers of E. coli O157 present and the risk of carcass contamination. Processing practices at this abattoir were adequate for minimizing contamination of carcasses, even when animals were heavily contaminated with E. coli O157.

Recirculating Immunomagnetic Separation and Optimal Enrichment Conditions for Enhanced Detection and Recovery of Low Levels of Escherichia coli O157:H7 from Fresh Leafy Produce and Surface Water

2007 ◽  
Vol 70 (12) ◽  
pp. 2717-2724 ◽  
Author(s):  
SUNEE HIMATHONGKHAM ◽  
MARY LEE DODD ◽  
JENNY K. YEE ◽  
DAVID K. LAU ◽  
RAYMOND G. BRYANT ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Surface Water ◽  
Real Time ◽  
Real Time Pcr ◽  
Immunomagnetic Separation ◽  
Escherichia Coli O157 ◽  
Simple Method ◽  
E Coli ◽  
Low Levels ◽  
Spinach Leaves

The objective of this study was to develop a rapid, simple method for enhanced detection and isolation of low levels of Escherichia coli O157:H7 from leafy produce and surface water using recirculating immunomagnetic separation (RIMS) coupled with real-time PCR and a standard culture method. The optimal enrichment conditions for the method also were determined. Analysis of real-time PCR data (CT values) suggested that incubation of lettuce and spinach leaves rather than rinsates provides better enrichment of E. coli O157:H7. Enrichment of lettuce or spinach leaves at 42°C for 5 h provided better detection than enrichment at 37°C. Extended incubation of surface water for 20 h at 42°C did not improve the detection. The optimized enrichment conditions were also employed with modified Moore swabs, which were used to sample flowing water sites. Positive isolation rates and real-time PCR results indicated an increased recovery of E. coli O157:H7 from all samples following the application of RIMS. Under these conditions, the method provided detection and/or isolation of E. coli O157:H7 at levels as low as 0.07 CFU/g of lettuce, 0.1 CFU/g of spinach, 6 CFU/100 ml of surface water, and 9 CFU per modified Moore swab. During a 6-month field study, modified Moore swabs yielded high isolation rates when deployed in natural watershed sites. The method used in this study was effective for monitoring E. coli O157:H7 in the farm environment, during postharvest processing, and in foodborne outbreak investigations.

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