A ratiometric SERS aptasensor based on catalytic hairpin self-assembly mediated cyclic signal amplification strategy for the reliable determination of E. coli O157:H7.

A ratiometric SERS aptasensor based on catalytic hairpin self-assembly (CHA) mediated cyclic signal amplification strategy was developed for the rapid and reliable determination of Escherichia coli O157:H7. The recognition probe was synthesized by modifying magnetic beads with blocked aptamers, and the SERS probe was constructed by functionalizing gold nanoparticles (Au NPs) with hairpin structured DNA and 4-mercaptobenzonitrile (4-MBN). The recognition probe captured E. coli O157:H7 specifically and released the blocker DNA, which activated the CHA reaction on the SERS probe and turned on the SERS signal of 6-carboxyl-x-rhodamine (ROX). Meanwhile, 4-MBN was used as an internal reference to calibrate the matrix interference. Thus, sensitive and reliable determination and quantification of E. coli O157:H7 was established using the ratio of the SERS signal intensities of ROX to 4-MBN. This aptasensor enabled detection of 2.44 × 102 CFU/mL of E. coli O157:H7 in approximately 3 h without pre-culture and DNA extraction. In addition, good reliability and excellent reproducibility were observed for the determination of E. coli O157:H7 in spiked water and milk samples. This study offered a new solution for the design of rapid, sensitive, and reliable SERS aptasensors.

An integrated magnetic separation enzyme-linked colorimetric sensing platform for field detection of Escherichia coli O157: H7 in food.

An intelligent colorimetric sensing platform integrated with in situ immunomagnetic separation function was developed for ultrasensitive detection of Escherichia coli O157: H7 (E. coli O157: H7) in food. Captured antibody modified magnetic nanoparticles (cMNPs) and detection antibody/horseradish peroxidase (HRP) co-functionalized AuNPs (dHAuNPs) were firstly synthesized for targeted enrichment and colorimetric assay of E. coli O157: H7, in which remarkable signal amplification was realized by loading large amounts of HRP on the surface of AuNPs. Coupling with the optical collimation attachments and embedded magnetic separation module, a highly integrated optical device was constructed, by which in situ magnetic separation and high-quality imaging of 96-well microplates containing E. coli O157: H7 was achieved with a smartphone. The concentration of E. coli O157: H7 could be achieved in one-step by performing digital image colorimetric analysis of the obtained image with a custom-designed app. This biosensor possesses high sensitivity (1.63 CFU/mL), short detecting time (3 h), and good anti-interference performance even in real-sample testing. Overall, the developed method is expected to be a novel field detection platform for foodborne pathogens in water and food as well as for the diagnosis of infections due to its portability, ease of operation, and high feasibility.

Impact of Western Diet on Enterohemorrhagic Escherichia coli Colonization in the Human In Vitro Mucosal Artificial Colon as Mediated by Gut Microbiota.

Enterohemorrhagic Escherichia coli (EHEC) is a major food-borne pathogen that causes human disease ranging from diarrhea to life-threatening complications. Accumulating evidence demonstrates that the Western diet enhances the susceptibility to enteric infection in mice, but the effect of diet on EHEC colonization and the role of human gut microbiota remains unknown. Our research aimed to investigate the effects of a Standard versus a Western diet on EHEC colonization in the human in vitro Mucosal ARtificial COLon (M-ARCOL) and the associated changes in the gut microbiota composition and activities. After donor selection using simplified fecal batch experiments, two M-ARCOL bioreactors were inoculated with a human fecal sample (n = 4) and were run in parallel, one receiving a Standard diet, the other a Western diet and infected with EHEC O157:H7 strain EDL933. EHEC colonization was dependent on the donor and diet in the luminal samples, but was maintained in the mucosal compartment without elimination, suggesting a favorable niche for the pathogen, and may act as a reservoir. The Western diet also impacted the bacterial short-chain fatty acid and bile acid profiles, with a possible link between high butyrate concentrations and prolonged EHEC colonization. The work demonstrates the application of a complex in vitro model to provide insights into diet, microbiota, and pathogen interactions in the human gut.

Hybrid nanoflower-based electrochemical lateral flow immunoassay for Escherichia coli O157 detection.

An electrochemical biosensor has been developed for detection of Escherichia coli O157 by integrating lateral flow with screen-printed electrodes. The screen-printed electrodes were attached under the lateral flow detection line, and organic-inorganic nanoflowers prepared from E. coli O157-specific antibodies as an organic component were attached to the lateral flow detection line. In the presence of E. coli O157, an organic-inorganic nanoflower-E. coli O157-antimicrobial peptide-labelled ferrocene sandwich structure is formed on the lateral flow detection line. Differential pulse voltammetry is applied using a smartphone-based device to monitor ferrocene on the detection line. The resulting electrochemical biosensor could specifically detect E. coli O157 with a limit of detection of 25 colony-forming units mL-1. Through substitution of antibodies of organic components in organic-inorganic nanoflowers, biosensors have great potential for the detection of other pathogens in biomedical research and clinical diagnosis.

Vibrio cholerae O1 and Escherichia coli O157:H7 from drinking water and wastewater in Addis Ababa, Ethiopia.

BACKGROUND: In Addis Ababa, Ethiopia, open ditches along innner roads in residential areas serve to convey domestic wastewater and rainwater away from residences. Contamination of drinking water by wastewater through faulty distribution lines could expose households to waterborne illnesses. This prompted the study to assess the microbiological safety of wastewater and drinking water in Addis Ababa, identify the pathogens therein, and determine their antibiotic resistance patterns. RESULTS VIBRIO CHOLERAE: O1, mainly Hikojima serotype, was isolated from 23 wastewater and 16 drinking water samples. Similarly, 19 wastewater and 10 drinking water samples yielded Escherichia coli O157:H7. V. cholerae O1 were 100% resistant to the penicillins (Amoxacillin and Ampicillin), and 51-82% were resistant to the cephalosporins. About 44% of the V. cholerae O1 isolates in this study were Extended Spectrum Beta-Lactamase (ESBL) producers. Moreover, 26% were resistant to Meropenem. Peperacillin/Tazobactam was the only effective ß-lactam antibiotic against V. cholerae O1. V. cholerae O1 isolates showed 37 different patterns of multiple resistance ranging from a minimum of three to a maximum of ten antimicrobials. Of the E. coli O157:H7 isolates, 71% were ESBL producers. About 96% were resistant to Ampicillin. Amikacin and Gentamicin were very effective against E. coli O157:H7 isolates. The isolates from wastewater and drinking water showed multiple antibiotic resistance against three to eight antibiotic drugs. CONCLUSIONS: Open ditches for wastewater conveyance along innner roads in residence areas and underground faulty municipal water distribution lines could be possible sources for V. cholerae O1 and E. coli O157:H7 infections to surrounding households and for dissemination of multiple drug resistance in humans and, potentially, the environment.

Ultra violet-C pretreatment enhances the antimicrobial efficacy of unpeeled carrots against subsequent contamination with Listeria monocytogenes.

To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C (UV-C) against subsequent contamination with Listeria monocytogenes. Carrots pretreated with UV-C (240 mJ/cm2) exhibited a significant antilisterial effect within 2 h. In fact, the population of UV-C-pretreated carrots decreased from 7.94 log CFU/cm2 to levels below the limit of detection (LOD; <1.65 log CFU/cm2) within 24 h. For carrots that were not pretreated with UV-C, 3-4 log reductions were found after 24 h. Carrots pretreated with UV-C exhibited antimicrobial activity against another gram-positive pathogen, Staphylococcus aureus, but not against the gram-negative pathogens, E. coli O157:H7 and Salmonella enterica. Pretreatment with UV-C created a lasting antimicrobial effect as introducing L. monocytogenes on carrots, 72 h post-UV-C treatment, still maintained the antilisterial effect. Notably, all UV-C doses in the range of 48-240 mJ/cm2 induced a lasting antilisterial effect. The bactericidal effects against L. monocytogenes were confirmed in three varieties of washed and unwashed carrots (Danvers, Nantes, and Chantenay). Fluorescence microscopy confirmed the bactericidal effect of UV-C-pretreated carrots on the survival of L. monocytogenes. Conclusively, pretreating carrots with UV-C can reduce the population of L. monocytogenes to levels below the LOD and may further prevent pathogen growth during cold storage. Additional studies are necessary to discern the mechanism underlying the bactericidal efficacy of UV-C-pretreated carrots.

Electroanalytical Platform for Rapid E. coli O157:H7 Detection in Water Samples.

There is a pressing need to enhance early detection methods of E. coli O157:H7 to mitigate the occurrence and consequences of pathogenic contamination and associated outbreaks. This study highlights the efficacy of a portable electrochemical sensing platform that operates without faradaic processes towards detecting and quantifying E. coli O157:H7. It is specifically tailored for quick identification in potable water. The assay processing time is approximately 5 min, addressing the need for swift and efficient pathogen detection. The sensing platform was constructed utilizing specific, monoclonal E. coli antibodies, based on single-capture, non-faradaic, electrochemical immunoassay principles. The E. coli sensor assay underwent testing over a wide concentration range, spanning from 10 to 105 CFU/mL, and a limit of detection (LoD) of 1 CFU/mL was demonstrated. Significantly, the sensor's performance remained consistent across studies, with both inter- and intra-study coefficients of variation consistently below 20%. To evaluate real-world feasibility, a comparative examination was performed between laboratory-based benchtop data and data obtained from the portable device. The proposed sensing platform exhibited remarkable sensitivity and selectivity, enabling the detection of minimal E. coli concentrations in potable water. This successful advancement positions it as a promising solution for prompt on-site detection, characterized by its portability and user-friendly operation. This study presents electrochemical-based sensors as significant contributors to ensuring food safety and public health. They play a crucial role in preventing the occurrence of epidemics and enhancing the supervision of water quality.

Thermal resistance of Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella in animal fat - Kinetic analysis and mathematical modeling.

The objective of this study was to evaluate the effect of fat on thermal resistance of L. monocytogenes, E. coli O157:H7, and Salmonella spp. A 4-strain cocktail of each microorganism was inoculated to beef tallow and heated isothermally at temperatures between 55 and 80℃. All survival curves did not follow the 1st-order inactivation kinetics but conformed to a two-stage linear pattern. The first stage was markedly less heat-resistant than the second, as manifested by significantly lower D values. The z values of E. coli O157 H7 and Salmonella spp. were 11.8 °C and 12.3 °C in the first stage (z1) but increased to 23.7 °C and 20.8 °C in the second stage (z2), respectively. For L. monocytogenes, while the z values were similar for both stages (z1 = 19.6 °C and z2 = 18.5 °C), the second stage D values are 3.6-5.9 times of those in the first stage. One-step analysis was used to fit the nonlinear curves to the Weibull model, yielding < 1 exponents for the model (0.495, 0.362, and 0.282, respectively, for L. monocytogenes, E. coli O157:H7, and Salmonella spp.), suggesting gradually increased thermal resistance during heating. The experimental results showed that these microorganisms could resist heating for longer time and at higher temperatures in tallow than they do in regular meats containing lower levels of fat. The kinetic models can be used to develop thermal processes to properly inactivate pathogens contaminated in the fat portions of meat products or other high fat products.

Using ultrasonic washing combined with UV-LEDs as a novel chemical-free method to disinfect fresh ready-to-eat produce.

The consumption of ready-to-eat fresh produce raises the issue of food-borne pathogen infections; thus, disinfecting ready-to-eat produce for commercial use, such as in homes and restaurants, is important to ensure food safety. Chemical sanitizers are typically used for disinfection. Ultraviolet-light emitting diodes (UV-LEDs) are a novel non-thermal disinfection technology that consumes less energy and generates less heat than traditional UV lamps, making them more appealing to consumers. In this study, we combined ultrasonic (US) washing method with UV-LEDs (US-UV-LEDs) to develop a technique for disinfecting fresh produce without using chemical sanitizers and compared its efficacy with three common household sanitizers ("84" (sodium hypochlorite) disinfectant, kettle descaler (citric acid), and vinegar (acetic acid)). In addition, we investigated the efficacy of this method in controlling pathogen numbers in the water used to wash (washing water) the produce to prevent cross-contamination between water and produce. Cherry tomatoes and lettuce were selected as produce models and Salmonella Typhimurium and Escherichia coli O157:H7 were used as the bacterial models. The results showed that US-UV-LEDs reduced the numbers of S. Typhimurium and E. coli O157:H7 on produce by 2.1-2.2 log CFU/g, consistent with the results achieved by the three household sanitizers; however, kettle descaler and vinegar had a limited effect (2.6-3.5 log CFU/mL) on residual pathogens in the washing water. Furthermore, we created washing water with low (754 mg/L) and high (1425 mg/L) chemical oxygen demand (COD) levels and determined the disinfection efficacy of "84" disinfectant and US-UV-LEDs. The results showed that US-UV-LEDs reduced the number of S. Typhimurium and E. coli O157:H7 by 2.0-2.1 and 1.8-2.1 log CFU/g under low and high COD levels, respectively, which was similar a result to that of "84" disinfectant. However, the residual pathogen numbers in the washing water were reduced to 1.4-1.9 log CFU/mL after treatment with US-UV-LED under high COD, whereas the pathogens were undetected in the washing water disinfected with "84" disinfectant. These results suggest that US-UV-LEDs have better application potential than acidic household sanitizers, but chlorine sanitizer remains the most effective disinfecting method.

Au-Pt Coating Improved Catalytic Stability of Au@AuPt Nanoparticles for Pressure-Based Point-of-Care Detection of Escherichia coli O157:H7.

Point-of-care testing (POCT) technologies facilitate onsite detection of pathogens in minutes to hours. Among various POCT approaches, pressure-based sensors that utilize gas-generating reactions, particularly those catalyzed by nanozymes (e.g., platinum nanoparticles, PtNPs, or platinum-coated gold nanoparticles, and Au@PtNPs) have been shown to provide rapid and sensitive detection capabilities. The current study introduces Au-Pt alloy-coated gold nanoparticles (Au@AuPtNPs), an innovative nanozyme with enhanced catalytic activity and relatively high stability. For pathogen detection, Au@AuPtNPs are modified with H1 or H2 hairpin DNAs that can be triggered to undergo a hybridization chain reaction (HCR) that leads to their aggregation upon recognition by an initiator strand (Ini) with H1-/H2-complementary aptamers tethered to magnetic beads (MBs). Pathogen binding to the aptamer exposes Ini, which then binds Au@AuPtNPs and initiates a HCR, resulting in Au@AuPtNP aggregation on MBs. These Au@AuPtNP aggregates exhibit strong catalysis of O2 from the H2O2 substrate, which is measured by a pressure meter, enabling detection of Escherichia coli (E. coli) O157:H7 at concentrations as low as 3 CFU/mL with high specificity. Additionally, E. coli O157:H7 could also be detected in simulated water and tea samples. This method eliminates the need for costly, labor- and training-intensive instruments, supporting its further testing and validation for deployment as a rapid-response POCT application in the detection of bacterial contaminants.

Rapid and Sensitive Quantification of Bacterial Viability Using Ratiometric Fluorescence Sensing.

Bacterial viability assessment plays an important role in food-borne pathogen detection and antimicrobial drug development. Here, we first used GelRed as a DNA-binding stain for a bacterial viability assessment. It was found that live bacteria were able to exclude GelRed, which however could easily penetrate dead ones and be absorbed nonspecifically on the bacterial periplasm. Cations were used to reduce the nonspecific adsorption and greatly increase the red fluorescence ratio of dead to live bacteria. Combined with SYTO 9 (a membrane-permeable dye) for double-staining, a ratiometric fluorescent method was established. Using Escherichia coli O157:H7 as a bacteria model, the ratiometric fluorescent method can probe dead bacteria as low as 0.1%. A linear correlation between the ratiometric fluorescence and the theoretical ratio of dead bacteria was acquired, with a correlation coefficient R2 of 0.97. Advantages in sensitivity, accuracy, and safety of the GelRed/SYTO9-based ratiometric fluorescent method against traditional methods were demonstrated. The established method was successfully applied to the assessment of germicidal efficacy of different heat treatments. It was found that even 50 °C treatment could lead to the death of minor bacteria. The as-developed method has many potential applications in microbial researches, and we believe it could be expanded to the viability assessment of mammalian cells.

On-Chip Capture, Raman-Silent Polymer Labeling, and Digital Mapping Analysis of Escherichia coli O157:H7 in Beverages All-in-One.

Escherichia coli O157:H7 is one of the most susceptible foodborne pathogens, easily causing food poisoning and other health risks. It is of great significance to establish a quantitative method with higher sensitivity and less time consumption for foodborne pathogens analysis. The Raman-silent signal has a good performance for avoiding interference from the food matrix so as to achieve accurate signal differentiation. In this work, we presented a preparation-mapping all-in-one method for digital mapping analysis. We prepared a functionalized Raman-silent polymer label of Escherichia coli O157:H7, which was captured on a porous 4-mercaptophenylboric acid@Ag foam chip. To improve accuracy and widen the detection range, a digital mapping quantitative strategy was employed in data extraction and processing. By transfer mapping information into digitized statistical results, the limitation of obtaining reproducible intensity values just by randomly selected spots on the substrate can be addressed. With a wide linear range of 1.0 × 101-1.0 × 105 CFU mL-1 and a limit of detection of 4.4 CFU mL-1, this all-in-one method had good sensitivity performance. Also, this method achieved good precision and selectivity in a series of experiments and was successfully applied to the analysis of beverage samples.

Simultaneous SERS-decoding detection of multiple pathogens in drinking water with home-made portable double-layer filtration and concentration device.

The engineering of a home-made portable double-layer filtration and concentration device with the common syringe for rapid analysis of water samples is reported. The core elements of the device were two installed filtration membranes with different pore sizes for respective functions. The upper filtration membrane was used for preliminary intercepting large interfering impurities (interception membrane), while the lower filtration membrane was used for collecting multiple target pathogens (enrichment membrane) for determination. This combination can make the contaminated environmental water, exemplified by surface water, filtrated quickly through the device and just retained the target bacteria of Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes on the lower enrichment membrane. Integrating with surface-enhanced Raman spectra (SERS) platform to decode the SERS-Tags (SERS-TagCVa, SERS-TagR6G, and SERS-TagMB) already labeled on each of the enriched bacteria based the antibody-mediated immuno-recognition effect, fast separation, concentration, and detection of multiple pathogenic bacteria from the bulk of contaminated environmental water were realized. Results show that within 30 min, all target bacteria in the lake water can be simultaneously and accurately measured in the range from 101 to 106 CFU mL-1 with detection limit of 10.0 CFU mL-1 without any pre-culture procedures. This work highlights the simplicity, rapidness, cheapness, selectivity, and the robustness of the constructed method for simultaneous detecting multiple pathogens in aqueous samples. This protocol opens a new avenue for facilitating the development of versatile analytical tools for drinking water and food safety monitoring in underdeveloped or developing countries.

Identification and evaluation of Escherichia coli strain ATCC 8739 as a surrogate for thermal inactivation of enterohemorrhagic Escherichia coli in fruit nectars: Impact of applied techniques on the decimal reduction time.

The objective of this study was to identify a suitable surrogate for E. coli O157:H7 strain 19685/91 and O113:H21 strain TS18/08, by assessing their thermal resistance at temperatures of 60 °C, 65 °C, and 72 °C in strawberry nectar. The influence of the matrix and the research methodology on the decimal reduction time (D-value) was investigated. Thermal kinetics and safety assessment demonstrated that E. coli ATCC 8739 is a suitable surrogate. The study demonstrated that the presence of fruit particles in the nectar increased thermal resistance of the tested strains. Variations in D-values were observed depending on the research method employed, with D-values in glass capillaries were up to 6.6 times lower compared to larger sample volumes. Encapsulation of E. coli ATCC 8739 exhibited high efficiency of 90.25 ± 0.26% and maintained stable viable counts after 26 days of storage in strawberry nectar at 4 °C. There were no significant differences in thermal resistance between surrogates directly inoculated into strawberry nectar and those encapsulated in alginate beads. Additionally, the encapsulated strains did not migrate outside the beads. Therefore, encapsulated E. coli ATCC 8739 in alginate beads can be effectively utilized in industrial settings to validate thermal treatments as a reliable and safe method.

Increased resistance against tellurite is conferred by a mutation in the promoter region of uncommon tellurite resistance gene tehB in the ter-negative Shiga toxin-producing Escherichia coli O157:H7.

Resistance to potassium tellurite (PT) is an important indicator in isolating Shiga toxin-producing Escherichia coli (STEC) O157:H7 and other major STEC serogroups. Common resistance determinant genes are encoded in the ter gene cluster. We found an O157:H7 isolate that does not harbor ter but is resistant to PT. One nonsynonymous mutation was found in another PT resistance gene, tehA, through whole-genome sequence analyses. To elucidate the contribution of this mutation to PT resistance, complementation of tehA and the related gene tehB in isogenic strains and quantitative RT‒PCR were performed. The results indicated that the point mutation not only changed an amino acid of tehA, but also was positioned on a putative internal promoter of tehB and increased PT resistance by elevating tehB mRNA expression. Meanwhile, the amino acid change in tehA had negligible impact on the PT resistance. Comprehensive screening revealed that 2.3% of O157:H7 isolates in Japan did not harbor the ter gene cluster, but the same mutation in tehA was not found. These results suggested that PT resistance in E. coli can be enhanced through one mutational event even in ter-negative strains. IMPORTANCE: Selective agents are important for isolating Shiga toxin-producing Escherichia coli (STEC) because the undesirable growth of microflora should be inhibited. Potassium tellurite (PT) is a common selective agent for major STEC serotypes. In this study, we found a novel variant of PT resistance genes, tehAB, in STEC O157:H7. Molecular experiments clearly showed that one point mutation in a predicted internal promoter region of tehB upregulated the expression of the gene and consequently led to increased resistance to PT. Because tehAB genes are ubiquitous across E. coli, these results provide universal insight into PT resistance in this species.

3-D stochastic modeling approach in thermal inactivation: estimation of thermal survival kinetics of Escherichia coli O157:H7 in a hamburger after exposure to desiccation stress.

Desiccation tolerance of pathogenic bacteria is one strategy for survival in harsh environments, which has been studied extensively. However, the subsequent survival behavior of desiccation-stressed bacterial pathogens has not been clarified in detail. Herein, we demonstrated that the effect of desiccation stress on the thermotolerance of Escherichia coli O157:H7 in ground beef was limited, and its thermotolerance did not increase. E. coli O157:H7 was inoculated into a ground beef hamburger after exposure to desiccation stress. We combined a bacterial inactivation model with a heat transfer model to predict the survival kinetics of desiccation-stressed E. coli O157:H7 in a hamburger. The survival models were developed using the Weibull model for two-dimensional pouched thin beef patties (ca. 1 mm), ignoring the temperature gradient in the sample, and a three-dimensional thick beef patty (ca. 10 mm), considering the temperature gradient in the sample. The two-dimensional (2-D) and three-dimensional (3-D) models were subjected to stochastic variations of the estimated Weibull parameters obtained from 1,000 replicated bootstrapping based on isothermal experimental observations as uncertainties. Furthermore, the 3-D model incorporated temperature gradients in the sample calculated using the finite element method. The accuracies of both models were validated via experimental observations under non-isothermal conditions using 100 predictive simulations. The root mean squared errors in the log survival ratio of the 2-D and 3-D models for 100 simulations were 0.25-0.53 and 0.32-2.08, respectively, regardless of the desiccation stress duration (24 or 72 h). The developed approach will be useful for setting appropriate process control measures and quantitatively assessing food safety levels.IMPORTANCEAcquisition of desiccation stress tolerance in bacterial pathogens might increase thermotolerance as well and increase the risk of foodborne illnesses. If a desiccation-stressed pathogen enters a kneaded food product via cross-contamination from a food-contact surface and/or utensils, proper estimation of the internal temperature changes in the kneaded food during thermal processing is indispensable for predicting the survival kinetics of desiccation-stressed bacterial cells. Various survival kinetics prediction models that consider the uncertainty or variability of pathogenic bacteria during thermal processing have been developed. Furthermore, heat transfer processes in solid food can be estimated using finite element method software. The present study demonstrated that combining a heat transfer model with a bacterial inactivation model can predict the survival kinetics of desiccation-stressed bacteria in a ground meat sample, corresponding to the temperature gradient in a solid sample during thermal processing. Combining both modeling procedures would enable the estimation of appropriate bacterial survival kinetics in solid food.

Fluorescent biosensor based on magnetic separation platform and spore-like breakable organosilica nanocapsules controlled-release carbon dots for the detection of Escherichia coli O157:H7.

Ultrasensitive and rapid detection of low concentration of Escherichia coli O157: H7 (E. coli O157:H7) in food is essential for food safety and public health. In this study, A novel fluorescence signal amplification biosensor based on magnetic separation platform and red fluorescent carbon dots (R-CDs)-encapsulated breakable organosilica nanocapsules (BONs) for ultrasensitive detection of E. coli O157:H7 was established. Wulff-type boronic acid functionalized magnetic nanoparticles (MNPs@B-N/APBA) with broad-spectrum bacterial recognition ability were synthesized for the first time to recognize and capture E. coli O157: H7 in food samples. R-CDs@BONs labeled with anti-E. coli O157:H7 monoclonal antibody (mAb@R-CDs@BONs-NH2) were used as the second recognition element to ensure the specificity for E. coli O157:H7 and form MNPs@B-N/APBA∼ E. coli O157:H7∼mAb@R-CDs@BONs-NH2 sandwich complexes, followed by releasing R-CDs to generate amplified fluorescence response signals for quantitative detection of E. coli O157:H7. The proposed method had a limit of detection with 25 CFU/mL in pure culture and contaminated lettuce samples, which the whole detection process took about 120 min. This fluorescence signal amplification biosensor has the potential to detect other pathogens in food by altering specific antibodies.

ENTEROHEMORRHAGIC ESCHERICHIA COLI LEADING TO HAEMOLYTIC UREMIC SYNDROME - CASE STUDY AND REVIEW.

Escherichia coli is a gram-negative bacillus and considered to be the normal pathogen of intestinal and extraintestinal manifestations depending upon the strain. A variety of strains exist that are responsible for causing myriads of clinical presentation. E.coli O157: H7 being the most common and severe bacterial pathogen is the leading cause of bloody diarrhea. EHEC (Enterohemorrhagic E.coli) is responsible for causing severe complications like HC (Hemorrhagic colitis). Herein, we present the case of a young girl with E.coli O157:H7 infection and review the related literature. A previously healthy 37-year-old female presented with bloody diarrhea, fever, headache, and lower abdominal pain. As per history she had eaten a hamburger, denied any recent travel and absence of inflammatory bowel disease or bloody stools in family history. Physical examination revealed normal vital signs and the physical findings were unremarkable except for severe abdominal pain. Her stool was hem-occult positive. The complete blood count was within normal limits except neutrophilia and leukocytosis. An abdominal ultrasound showed thickened bowel loops consistent with colitis. First week of her hospital course, she continued to have bloody diarrhea and severe abdominal pain. Her final stool submitted to the laboratory on day 7 was consistent with a blood clot, following her developed low urine output and hematuria, with a serum creatinine of 2.1 mg/dl on day 5. Her renal symptoms were treated with fluids. She was given supportive treatment, and her platelet count and hemoglobin were stabilized. In early stages of bloody diarrhea, parental hydration plays a major role in accelerating volume expansion. Rapid stool analysis for these bacteria can alert specialists to deal with severe complications like HUS.

Detection of the chuA gene encoding the invasive enterohemorrhagic species Escherichia coli 0157:H7 using qPCR in horse feces samples on Sumbawa Island, Indonesia.

Background: Bacterial identification can be done using various testing techniques. Molecular techniques are often used to research dangerous diseases, an approach using genetic information on the pathogenic agent. The enterohemorrhagic invasive species Escherichia coli 0157:H7 was identified from the feces of working horses on the island of Sumbawa. Another advance in molecular technology is genome amplification with qPCR which is the gold standard for detecting E. coli. Aim: This study aims to detect and identify the invasive species E. coli 0157:H7 using the gene encoding chuA with the qPCR method sourced from horse feces. Methods: Fresh fecal samples from horses on Sumbawa Island were isolated and identified, then continued with molecular examination using the gene encoding chuA using the qPCR method. Results: qPCR testing in this study showed that six sample isolates that were positive for E. coli 0157:H7 were detected for the presence of the chuA gene, which is a gene coding for an invasive species of E. coli bacteria. The highest to lowest Cq values and Tm from the qPCR results of the sample isolates were 15.98 (4KJ), 14.90 (19KG), 14.6 (3KJ), 13.77 (20KG), 12.56 (5KGB), and 12.20 (6KJ). Tm values are 86.7 (4KJ), 86.69 (3KJ), 86.56 (5KGB), 85.88 (20KGB), 85.81 (19KG), and 85.74 (6KJ). Conclusion: Validation, standardization of the development, and modification of qPCR technology must be carried out to harmonize testing throughout to avoid wrong interpretation of the test results so that the determination of actions to eradicate and control diseases originating from animals in the field does not occur.

Shiga Toxin-Producing Escherichia coli O157:H7 Illness Outbreak Associated with Untreated, Pressurized, Municipal Irrigation Water - Utah, 2023.

During July-September 2023, an outbreak of Shiga toxin-producing Escherichia coli O157:H7 illness among children in city A, Utah, caused 13 confirmed illnesses; seven patients were hospitalized, including two with hemolytic uremic syndrome. Local, state, and federal public health partners investigating the outbreak linked the illnesses to untreated, pressurized, municipal irrigation water (UPMIW) exposure in city A; 12 of 13 ill children reported playing in or drinking UPMIW. Clinical isolates were genetically highly related to one another and to environmental isolates from multiple locations within city A's UPMIW system. Microbial source tracking, a method to indicate possible contamination sources, identified birds and ruminants as potential sources of fecal contamination of UPMIW. Public health and city A officials issued multiple press releases regarding the outbreak reminding residents that UPMIW is not intended for drinking or recreation. Public education and UPMIW management and operations interventions, including assessing and mitigating potential contamination sources, covering UPMIW sources and reservoirs, indicating UPMIW lines and spigots with a designated color, and providing conspicuous signage to communicate risk and intended use might help prevent future UPMIW-associated illnesses.