scholarly journals Sustainable, Alginate-Based Sensor for Detection of Escherichia coli in Human Breast Milk

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1145
Author(s):  
Nicholas Kikuchi ◽  
Margaret May ◽  
Matthew Zweber ◽  
Jerard Madamba ◽  
Craig Stephens ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Breast Milk ◽  
Pathogen Detection ◽  
Protein Extraction ◽  
Limit Of Detection ◽  
Pcr Amplification ◽  
Human Breast Milk ◽  
Blue Color ◽  
E Coli ◽  
The Cost

There are no existing affordable diagnostics for sensitive, rapid, and on-site detection of pathogens in milk. To this end, an on-site colorimetric-based sustainable assay has been developed and optimized using an L16 (54) Taguchi design to obtain results in hours without PCR amplification. To determine the level of Escherichia coli (E. coli) contamination, after induction with 150 µL of breast milk, the B-Per bacterial protein extraction kit was added to a solution containing an alginate-based microcapsule assay. Within this 3 mm spherical novel sensor design, X-Gal (5-Bromo-4-Chloro-3-Indolyl β-d-Galactopyranoside) was entrapped at a concentration of 2 mg/mL. The outward diffusing X-Gal was cleaved by β-galactosidase from E. coli and dimerized in the solution to yield a blue color after incubation at 40 °C. Color intensity was correlated with the level of E. coli contamination using a categorical scale. After an 8 h incubation period, a continuous imaging scale based on intensity normalization was used to determine a binary lower limit of detection (LOD), which corresponded to 102 colony forming unit per mL (CFU/mL) and above. The cost of the overall assay was estimated to be $0.81 per sample, well under the $3 benchmark for state-of-the-art immune-based test kits for pathogen detection in biofluids. Considering the reported binary LOD cutoff of 102 CFU/mL and above, this proposed hydrogel-based assay is suited to meet global requirements for screening breast milk or milk for pathogenic organisms of 104 CFU/mL, with a percentage of false positives to be determined in future efforts.

Lactobacillus rhamnosus from human breast milk shows therapeutic function against foodborne infection by multi-drug resistant Escherichia coli in mice

2020 ◽  
Vol 11 (1) ◽  
pp. 435-447 ◽  
Author(s):  
Na Li ◽  
Bing Pang ◽  
Guanwen Liu ◽  
Xixi Zhao ◽  
Xiaoguang Xu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Breast Milk ◽  
Therapeutic Efficacy ◽  
Lactobacillus Rhamnosus ◽  
Human Breast Milk ◽  
Drug Resistant ◽  
Human Breast ◽  
E Coli ◽  
Therapeutic Function ◽  
Foodborne Infection

Lactobacillus rhamnosus shows higher therapeutic efficacy than antibiotic to treat drug-resistant E. coli infection in aspects of fast reducing coliform counts, increasing Lactobacillus amounts, and diminishing inflammation.

Changes in Aerobic Plate and Escherichia coli–Coliform Counts and in Populations of Inoculated Foodborne Pathogens on Inshell Walnuts during Storage

2016 ◽  
Vol 79 (7) ◽  
pp. 1143-1153 ◽  
Author(s):  
JOHN C. FRELKA ◽  
GORDON R. DAVIDSON ◽  
LINDA J. HARRIS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Relative Humidity ◽  
Low Temperature ◽  
Foodborne Pathogens ◽  
Limit Of Detection ◽  
Sampling Time ◽  
E Coli ◽  
Plate Counts ◽  
Forced Air

ABSTRACT After harvest, inshell walnuts are dried using low-temperature forced air and are then stored in bins or silos for up to 1 year. To better understand the survival of bacteria on inshell walnuts, aerobic plate counts (APCs) and Escherichia coli–coliform counts (ECCs) were evaluated during commercial storage (10 to 12°C and 63 to 65% relative humidity) over 9 months. APCs decreased by 1.4 to 2.0 log CFU per nut during the first 5 months of storage, and ECCs decreased by 1.3 to 2.2 log CFU per nut in the first month of storage. Through the remaining 4 to 8 months of storage, APCs and ECCs remained unchanged (P > 0.05) or decreased by <0.15 log CFU per nut per month. Similar trends were observed on kernels extracted from the inshell walnuts. APCs and ECCs were consistently and often significantly higher on kernels extracted from visibly broken inshell walnuts than on kernels extracted from visibly intact inshell walnuts. Parameters measured in this study were used to determine the survival of five-strain cocktails of E. coli O157:H7, Listeria monocytogenes, and Salmonella inoculated onto freshly hulled inshell walnuts (~8 log CFU/g) after simulated commercial drying (10 to 12 h; 40°C) and simulated commercial storage (12 months at 10°C and 65% relative humidity). Populations declined by 2.86, 5.01, and 4.40 log CFU per nut for E. coli O157:H7, L. monocytogenes, and Salmonella, respectively, after drying and during the first 8 days of storage. Salmonella populations changed at a rate of −0.33 log CFU per nut per month between days 8 and 360, to final levels of 2.83 ± 0.79 log CFU per nut. E. coli and L. monocytogenes populations changed by −0.17 log CFU per nut per month and −0.26 log CFU per nut per month between days 8 and 360, respectively. For some samples, E. coli or L. monocytogenes populations were below the limit of detection by plating (0.60 log CFU per nut) by day 183 or 148, respectively; at least one of the six samples was positive at each subsequent sampling time by either plating or by enrichment.

scholarly journals Alleviation of C⋅C Mismatches in DNA by the Escherichia coli Fpg Protein

2021 ◽  
Vol 12 ◽  
Author(s):  
Almaz Nigatu Tesfahun ◽  
Marina Alexeeva ◽  
Miglė Tomkuvienė ◽  
Aysha Arshad ◽  
Prashanna Guragain ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Excision Repair ◽  
Dna Lesions ◽  
Base Pairs ◽  
E Coli ◽  
Thymine Glycol ◽  
Base Excision ◽  
The Cost ◽  
Primary Substrate

DNA polymerase III mis-insertion may, where not corrected by its 3′→ 5′ exonuclease or the mismatch repair (MMR) function, result in all possible non-cognate base pairs in DNA generating base substitutions. The most thermodynamically unstable base pair, the cytosine (C)⋅C mismatch, destabilizes adjacent base pairs, is resistant to correction by MMR in Escherichia coli, and its repair mechanism remains elusive. We present here in vitro evidence that C⋅C mismatch can be processed by base excision repair initiated by the E. coli formamidopyrimidine-DNA glycosylase (Fpg) protein. The kcat for C⋅C is, however, 2.5 to 10 times lower than for its primary substrate 8-oxoguanine (oxo8G)⋅C, but approaches those for 5,6-dihydrothymine (dHT)⋅C and thymine glycol (Tg)⋅C. The KM values are all in the same range, which indicates efficient recognition of C⋅C mismatches in DNA. Fpg activity was also exhibited for the thymine (T)⋅T mismatch and for N4- and/or 5-methylated C opposite C or T, Fpg activity being enabled on a broad spectrum of DNA lesions and mismatches by the flexibility of the active site loop. We hypothesize that Fpg plays a role in resolving C⋅C in particular, but also other pyrimidine⋅pyrimidine mismatches, which increases survival at the cost of some mutagenesis.

Prevalence of Escherichia coli O157 in Cattle and Swine in Central Mexico†

2004 ◽  
Vol 67 (10) ◽  
pp. 2274-2276 ◽  
Author(s):  
T. R. CALLAWAY ◽  
R. C. ANDERSON ◽  
G. TELLEZ ◽  
C. ROSARIO ◽  
G. M. NAVA ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Limit Of Detection ◽  
The United States ◽  
Sensitive Detection ◽  
Central Mexico ◽  
Escherichia Coli O157 ◽  
Immunomagnetic Bead ◽  
E Coli ◽  
Detection Techniques ◽  
Swine Farms

Escherichia coli O157:H7 is a foodborne pathogenic bacterium that can reside undetected in the gastrointestinal tract of cattle because colonization by this bacterium is asymptomatic. Recent research has indicated that swine can carry and transmit this pathogen as well. The development of more advanced and sensitive detection techniques has improved the limit of detection and increased sensitivity for this important pathogen. This study was undertaken to determine the prevalence of E. coli O157 in cattle and swine in Mexico with the more sensitive detection technique of immunomagnetic bead separation. Samples (n = 60 per farm) were taken from four cattle and four swine farms (n = 240 cattle samples, n = 240 swine samples) located throughout central Mexico in October 2001. The prevalence of E. coli O157 was found to be only 1.25% on cattle farms and 2.1% on swine farms. The prevalence in cattle in this study is lower than that reported in the United States and could be related to the lower reported prevalence of E. coli O157 in humans in Mexico. However, further research is needed to verify prevalence throughout other regions of Mexico, as well as prevalence during other seasons of the year.

Low Prevalence of Salmonella and Shiga Toxin–Producing Escherichia coli in Lymph Nodes of Australian Beef Cattle

2017 ◽  
Vol 80 (12) ◽  
pp. 2105-2111 ◽  
Author(s):  
Gavin Bailey ◽  
Long Huynh ◽  
Lachlan Govenlock ◽  
David Jordan ◽  
Ian Jenson
Keyword(s):  
Escherichia Coli ◽  
Lymph Nodes ◽  
Shiga Toxin ◽  
Limit Of Detection ◽  
Ground Beef ◽  
Plate Count ◽  
Salmonella Spp ◽  
Live Animal ◽  
E Coli ◽  
Low Prevalence

ABSTRACT Salmonella contamination of ground beef has been viewed as originating from the surface of carcasses. Recent studies have identified lymph nodes as a potential source of Salmonella contamination because these tissues play an active role in containment of pathogens in the live animal and because some lymph nodes are unavoidably present in manufacturing beef trimmings or primal cuts that may be incorporated into ground beef. A survey was conducted of the microbiological status of lymph nodes from Australian cattle at the time of slaughter to determine the prevalence of microbiological contamination. Sets of lymph nodes (n = 197), consisting of the superficial cervical (prescapular), prepectoral, axillary, presternal, popliteal, ischiatic, subiliac (precrural), coxalis, and iliofemoralis (deep inguinal), were collected from five geographically separated Australian abattoirs over a period of 14 months. Samples were tested for the presence of Salmonella spp. and Shiga toxin–producing Escherichia coli by BAX PCR assay. Aerobic plate count, E. coli, and coliforms were enumerated with a lower limit of detection of 80 CFU per node. The observed prevalence of Salmonella within peripheral lymph nodes was 0.48% (7 of 1,464). Two of the seven lymph nodes in which Salmonella organisms were detected came from the same animal. Grass-fed, grain-fed, and cull dairy cattle were all found to have detectable Salmonella in lymph nodes. All Salmonella detections occurred during cooler months of the year. No Shiga toxin–producing E. coli were detected. Aerobic microorganisms were detected above the limit of quantification in 3.2% of nodes (median count 2.24 log per node), and E. coli was detected in 0.8% of nodes (median count 3.05 log per node). The low prevalence of Salmonella and low concentration of aerobic microorganisms in Salmonella-positive lymph nodes of Australian cattle at the time of slaughter suggest that the likelihood of lymph nodes contributing significantly to the presence of Salmonella in ground beef is low.

Development of Digoxigenin-Labeled PCR Amplicon Probes for Use in the Detection and Identification of Enteropathogenic Yersinia and Shiga Toxin–Producing Escherichia coli from Foods

1999 ◽  
Vol 62 (5) ◽  
pp. 438-443 ◽  
Author(s):  
STEPHEN D. WEAGANT ◽  
JAMES A. JAGOW ◽  
KAREN C. JINNEMAN ◽  
CURTIS J. OMIECINSKI ◽  
CHARLES A. KAYSNER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pcr Amplification ◽  
Health Concern ◽  
E Coli ◽  
Hybridization Probes ◽  
Detection And Identification ◽  
Contaminated Food ◽  
Enteropathogenic Yersinia ◽  
Labeled Probe ◽  
Shelf Stable

By including digoxigenin-11-dUTP in a polymerase chain reaction (PCR), amplification products were produced that contained nonisotopic markers for use as DNA hybridization probes. Because these labeled amplicons encode pathogenic traits for specific foodborne bacteria, they can be used to detect the presence of potentially virulent organisms that may be present in foods. This technology allows the synthesis of a variety of shelf-stable probe reagents for detecting a number of foodborne microbes of public health concern. We used this technology to detect four genes in two potential pathogens: virF and yadA in enteropathogenic Yersinia and stx1 and stx2 in Shiga-like toxin–producing Escherichia coli. Results of DNA hybridizations of dot blots of 68 Yersinia strains and 24 of 25 E. coli strains were consistent with results of equivalent PCR analyses. DNA colony hybridization with nonisotopic virF probes of colonies arising on spread plates from artificially contaminated food homogenates was able to detect potentially pathogenic Y. enterocolitica. When compared with oligonucleotide probes, amplicon probes are much less sensitive to changes in hybridization and wash temperatures, allowing greater reproducibility. Labeled probe preparations were reused more than five times and have been stored at −20°C for more than 8 months. This method conveniently generates probes that are safe, stable, inexpensive, reusable, and reliable.

Shellac Formulations To Reduce Epiphytic Survival of Coliform Bacteria on Citrus Fruit Postharvest†

2001 ◽  
Vol 64 (11) ◽  
pp. 1756-1760 ◽  
Author(s):  
RAYMOND G. McGUIRE ◽  
ROBERT D. HAGENMAIER
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Limit Of Detection ◽  
Citrus Fruit ◽  
Enterobacter Aerogenes ◽  
Coliform Bacteria ◽  
Undetectable Level ◽  
Neutral Solution ◽  
E Coli ◽  
Epiphytic Survival

Survival of the coliform bacteria Enterobacter aerogenes and Escherichia coli was monitored in a neutral carboxyme-thylcellulose formulation and in shellac formulations with various pH and concentrations of ethanol and the preservative paraben; populations were subsequently measured from the surface of citrus fruit coated with these formulations. Numbers of the two bacteria increased over 24 h from 106 CFU/ml to approximately 108 CFU/ml in the carboxymethylcellulose solution, but over this time numbers remained little changed in the neutral solution of shellac. The Enterobacter was more tolerant of alcohol over a 3-h period; although its numbers in a shellac solution with 10% ethanol dropped from more than 106 CFU/ml to just over 103 CFU/ml, E. coli and a third species, Klebsiella pneumoniae, declined toward the limit of detection (5 CFU/ml) during this time. The addition of morpholine to increase the formulation pH to 9.0 caused numbers of bacteria to plummet to an undetectable level within 30 to 60 min. On Ruby Red grapefruit and Valencia oranges in storage at 13°C numbers of E. aerogenes and E. coli declined over 2 weeks from 105 CFU/cm2 to less than 2.5 × 101, but most of the loss in numbers occurred within 1 day. Numbers remained significantly less on shellacked fruit compared with those applied in the carboxymethylcellulose coating, and a shellac coating prepared from a pH 9 solution was more toxic to these species than one in which 12% ethanol had been added to the neutral formulation. The addition of the preservative paraben in the basic shellac was further inhibitory.

Association of Enterohemorrhagic Escherichia coliHemolysin with Serotypes of Shiga-Like-Toxin-ProducingEscherichia coli of Human and Bovine Origins

1998 ◽  
Vol 64 (11) ◽  
pp. 4134-4141 ◽  
Author(s):  
Carlton Gyles ◽  
Roger Johnson ◽  
Anli Gao ◽  
Kim Ziebell ◽  
Denis Pierard ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Severe Disease ◽  
Sheep Erythrocyte ◽  
Pcr Amplification ◽  
E Coli ◽  
Hemolysin Gene ◽  
Group 3 ◽  
Group 2 ◽  
Bovine Feces ◽  
Group 1

ABSTRACT In this study we investigated whether the enterohemorrhagicEscherichia coli (EHEC) hemolysin gene ehxAcould be used as an indicator of pathogenicity in Shiga-like-toxin-producing Escherichia coli (SLTEC) isolates. The isolates in a collection of 770 SLTEC strains of human and bovine origins were assigned to group 1 (230 human and 138 bovine SLTEC isolates belonging to serotypes frequently implicated in human disease), group 2 (85 human and 183 bovine isolates belonging to serotypes less frequently implicated in disease), and group 3 (134 bovine isolates belonging to serotypes not implicated in disease). PCR amplification was used to examine all of the SLTEC isolates for the presence of ehxA and the virulence-associated geneseae, slt-I, and slt-II. The percentages of human isolates in groups 1 and 2 that were positive forehxA were 89 and 46%, respectively, and the percentages of bovine isolates in groups 1 to 3 that were positive forehxA were 89, 51, and 52%, respectively. The percentages of human isolates in groups 1 and 2 that were positive foreae were 92 and 27%, respectively, and the percentages of bovine isolates in groups 1 to 3 that were positive for eaewere 78, 15, and 19%, respectively. The frequencies of bothehxA and eae were significantly higher for group 1 isolates than for group 2 isolates. The presence of the ehxA gene was associated with serotype, as was the presence of the eae gene. Some serotypes, such as O117:H4, lacked both eae and ehxA and have been associated with severe disease, but only infrequently. Theslt-I genes were more frequent in group 1 isolates than in group 2 isolates, and the slt-II genes were more frequent in group 2 isolates than in group 1 isolates. In a second experiment we determined the occurrence of the ehxA andslt genes in E. coli isolated from bovine feces. Fecal samples from 175 animals were streaked onto washed sheep erythrocyte agar plates. Eight E. coli-like colonies representing all of the morphological types were transferred to MacConkey agar. A total of 1,080 E. coli isolates were examined, and the ehxA gene was detected in 12 independent strains, only 3 of which were positive for slt. We concluded that the ehxA gene was less correlated with virulence than the eae gene was and that EHEC hemolysin alone has limited value for screening bovine feces for pathogenic SLTEC because of presence of the ehxA gene in bovine isolates that are not SLTEC.

scholarly journals Recent Progress on the Electrochemical Biosensing of Escherichia coli O157:H7: Material and Methods Overview

Biosensors ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 54 ◽  
Author(s):  
Nasrin Razmi ◽  
Mohammad Hasanzadeh ◽  
Magnus Willander ◽  
Omer Nur
Keyword(s):  
Escherichia Coli ◽  
Pathogen Detection ◽  
Recent Progress ◽  
Electrochemical Sensors ◽  
Solid Phase ◽  
Great Promise ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Electrochemical Biosensing ◽  
Sensitivity And Selectivity

Escherichia coli O157:H7 (E. coli O157:H7) is a pathogenic strain of Escherichia coli which has issued as a public health threat because of fatal contamination of food and water. Therefore, accurate detection of pathogenic E. coli is important in environmental and food quality monitoring. In spite of their advantages and high acceptance, culture-based methods, enzyme-linked immunosorbent assays (ELISAs), polymerase chain reaction (PCR), flow cytometry, ATP bioluminescence, and solid-phase cytometry have various drawbacks, including being time-consuming, requiring trained technicians and/or specific equipment, and producing biological waste. Therefore, there is necessity for affordable, rapid, and simple approaches. Electrochemical biosensors have shown great promise for rapid food- and water-borne pathogen detection. Over the last decade, various attempts have been made to develop techniques for the rapid quantification of E. coli O157:H7. This review covers the importance of E. coli O157:H7 and recent progress (from 2015 to 2020) in the development of the sensitivity and selectivity of electrochemical sensors developed for E. coli O157:H7 using different nanomaterials, labels, and electrochemical transducers.

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