A review on detection methods used for foodborne pathogens

Optimized detection of Salmonella typhimurium using aptamer lateral flow assay

Salmonella typhimurium, a pathogenic bacterium with significant implications in medicine and the food industry, poses a substantial threat by causing foodborne illnesses such as typhoid fever. Accurate diagnosis of S. typhimurium is challenging due to its overlap symptoms with various diseases. This underscores the need for a precise and efficient diagnostic approach. In this study, we developed a biosensor using the Taguchi optimization method based on aptamer lateral flow assay (LFA) for the detection of S. typhimurium. Therefore, signal probe and nanobioprobe were designed using anti-Salmonella aptamer, conjugated with gold nanoparticles (GNPs), and used in LFA. The strategy of this test is based on a competitive format between the bacteria immobilized on the membrane and the bacteria present in the tested sample. Moreovere, the optimization of various factors affecting the aptamer LFA, including the concentration of bacteria (immobilized and into the sample) and the concentration of nanobioprop, were performed using the Taguchi test designing method. The data showed that the optimal conditions for the LFA reaction was 108 CFU/mL of immobilized bacteria and 1.5 μg/μL of nanobioprop concentration. Then, the visual detection limit of S. typhimurium was estimated as 105 CFU/mL. The reaction results were obtained within 20 min, and there were no significant cross-reactions with other food pathogens. In conclusion, the aptamer-LFA diagnostic method, optimized using the Taguchi approach, emerges as a reliable, straightforward, and accurate tool for the detection of S. typhimurium. Overall, this method can be a portable diagnostic kit for the detection and identification of bacteria.

Advances in aptamer-based biosensors for monitoring foodborne pathogens

Biosensors are analytical devices for detecting a wide range of targets, including cells, proteins, DNA, enzymes, and chemical and biological compounds. They mostly rely on using bioprobes with a high binding affinity to the target for specific detection. However, low specificity and effectiveness of the conventional biosensors has led to the search for novel materials, that can specifically detect biomolecules. Aptamers are a group of single-stranded DNA or RNA oligonucleotides, that can bind to their targets with high specificity and serve as effective bioprobes for developing aptamer-based biosensors. Aptamers have a shorter production time, high stability, compared to traditional bioprobes, and possess ability to develop them for specific target molecules for tailored applications. Thus, various aptasensing approaches, including electrochemical, optical, surface plasmon resonance and chip-dependent approaches, have been investigated in recent times for various biological targets, including foodborne pathogens. Hence, this article is an overview of various conventional foodborne pathogen detection methods, their limitations and the ability of aptamer-based biosensors to overcome those limitations and replace them. In addition, the current status and advances in aptamer-based biosensors for the detection of foodborne pathogens to ensure food safety were also discussed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05889-8.

Flow cytometry: Unravelling the real antimicrobial and antibiofilm efficacy of natural bioactive compounds

Flow cytometry (FCM) provides unique information on bacterial viability and physiology, allowing a real-time early warning antimicrobial and antibiofilm monitoring system for preventing the spread risk of foodborne disease. The present work used a combined culture-based and FCM approach to assess the in vitro efficacy of essential oils (EOs) from condiment plants commonly used in Mediterranean Europe (i.e., thyme EO, oregano EO, basil EO, and lemon EO) against planktonic and sessile cells of food-pathogenic Listeria monocytogenes 56 LY, and contaminant and alterative species Escherichia coli ATCC 25922 and Pseudomonas fluorescens ATCC 13525. Evaluation of the bacterial response to the increasing concentrations of natural compounds posed FCM as a crucial technique for the quantification of the live/dead, and viable but non-culturable (VBNC) cells when antimicrobial agents exert no real bactericidal action. Furthermore, the FCM results displayed higher numbers of viable bacteria expressed as Active Fluorescent Units (AFUs) with a greater level of repeatability compared with outcomes of the plate-count method. Overall, accurate counting of viable microbial cells is a critically important parameter in food microbiology, and flow cytometry provides an innovative approach with high-throughput potential for applications in the food industry as "flow microbiology".

Analytical methods for determining environmental contaminants of concern in water and wastewater

Control and prevention of environmental pollution have emerged as paramount global concerns. Anthropogenic activities, such as industrial discharges, agricultural runoff, and improper waste disposal, introduce a wide range of contaminants into various ecosystems. These pollutants encompass organic and inorganic compounds, particulates, microorganisms, and disinfection by-products, posing severe threats to human health, ecosystems, and the environment. Effective monitoring methods are indispensable for assessing environmental quality, identifying pollution sources, and implementing remedial measures. This paper suggests that the development and utilization of highly advanced analytical tools are both essential for the analysis of contaminants in water samples, presenting a foundational hypothesis for the review. This paper comprehensively reviews the development and utilization of highly advanced analytical tools which is mandatory for the analysis of contaminants in water samples. Depending on the specific pollutants being studied, the choice of analytical methods widely varies. It also reveals insights into the diverse applications and effectiveness of these methods in assessing water quality and contaminant levels. By emphasizing the critical role of the reviewed monitoring methods, this review seeks to deepen the understanding of pollution challenges and inspire innovative monitoring solutions that contribute to a cleaner and more sustainable global environment.•Urgent global concerns: control and prevention of pollution from diverse sources.•Varied contaminants, diverse methods: comprehensive review of analytical tools.•Inspiring a sustainable future: innovative monitoring for a cleaner environment.

Utilizing fab fragment-conjugated surface plasmon resonance-based biosensor for detection of Salmonella Enteritidis

Although antibodies, a key element of biorecognition, are frequently used as biosensor probes, the use of these large molecules can lead to adverse effects. Fab fragments can be reduced to allow proper antigen-binding orientation via thiol groups containing Fab sites that can directly penetrate Au sites chemically. In this study, the ability of the surface plasmon resonance (SPR) sensor to detect Salmonella was studied. Tris(2-carboxyethyl)phosphine was used as a reducing agent to obtain half antibody fragments. Sensor surface was immobilized with antibody, and bacteria suspensions were injected from low to high concentrations. Response units were changed by binding first reduced antibody fragments, then bacteria. The biosensor was able to determine the bacterial concentrations between 103 and 108 CFU/mL. Based on these results, the half antibody fragmentation method can be generalized for faster, label-free, sensitive, and selective detection of other bacteria species.

Determination of foodborne pathogens in minced beef by real-time PCR without culture enrichment

Meat provides the necessary environment for the growth of foodborne pathogens due to its features such as being rich in protein and having sufficient water activity. Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7, which can be transmitted through many foods, including water, and cause serious diseases, are among the significant pathogens. In the current study. Detection of Listeria monocytogenes, Escherichia coli and Salmonella enterica in 100 minced beef samples collected from different butchers and markets situated in the central districts of Erzurum province was performed by Real-Time PCR without pre-enrichment and DNA isolation. Linear regression equations of Ct values of standard pathogenic bacteria were created. Ct values of minced beef samples obtained as a result of Real-Time PCR analysis were substituted in the equations, and the amounts of pathogenic bacteria in the samples were determined. Listeria monocytogenes, Escherichia coli, and Salmonella enterica were detected in 45, 30, and 29 of 100 minced beef samples, respectively. It is known that the Real-Time PCR method, which is used to detect pathogenic bacteria, is more specific, fast, and reliable than conventional methods. According to the results obtained, it has been clearly observed that with our new approach, pathogenic bacteria growing on foods can be detected sensitively with less cost, shorter amount of time, and minimized workload without pre-enrichment and DNA isolation.

Raman spectroscopy-based microfluidic platforms: A promising tool for detection of foodborne pathogens in food products

Rapid and sensitive detection of foodborne pathogens in food products is paramount for ensuring food safety and public health. In the ongoing effort to tackle this issue, detection methods are continually researched and upgraded to achieve rapidity, sensitivity, portability, and cost-effectiveness. This review addresses the critical need for improved technique by focusing on Raman spectroscopy-based microfluidic platforms, which have shown potential in revolutionizing the field of foodborne pathogen analysis offering point-of-care diagnosis and multiplex detection. The key problem lies in the persistent threat of compromised food quality and public health due to inadequate pathogen detection. The review elucidates the various trapping strategies employed in a microfluidic platform, including optical trapping, electrical trapping, mechanical trapping, and acoustic trapping for the capture of microbial cells. Subsequently, the review delves into the key aspects of the application of microbial detection in food products, highlighting recent advances and challenges in the field. The integrated technique allows point-of-care application assessment, which is an attractive quality for in-line and real-time detection of foodborne pathogens. However, the application of the technique in food products is limited and requires further research to combat the complexity of the food matrix, reduced costs of production, and ensure real-time use for diverse pathogens. Ultimately, this review aims to propel advancements in microbial detection, thus promoting enhanced food safety through state-of-the-art technologies.

A colorimetric, photothermal, and fluorescent triple-mode CRISPR/cas biosensor for drug-resistance bacteria detection

A multimodal analytical strategy utilizing different modalities to cross-validate each other, can effectively minimize false positives or negatives and ensure the accuracy of detection results. Herein, we establish a colorimetric, photothermal, and fluorescent triple modal CRISPR/Cas12a detection platform (CPF-CRISPR). An MNPs-ssDNA-HRP signal probe is designed to act as a substrate to trigger three signal outputs. In the presence of the DNA target, MNPs-ssDNA-HRP is cleaved by the activated CRISPR/Cas12a, resulting in the release of HRP and generating short DNA strands with 3-terminal hydroxyl on magnetic beads. The released HRP subsequently catalyzed TMB-H2O2 reaction and oxidized TMB is used for colorimetric and photothermal signal detection. Under the catalysis of terminal deoxynucleotidyl transferase (TdT), the remaining short DNA strands are used as primers to form poly-T and function as scaffolds to form copper nanoclusters for fluorescent signal output. To verify the practical application of CPF-CRISPR, we employed MRSA as a model. The results demonstrate the platform's high accuracy and sensitivity, with a limit of detection of 101 CFU/mL when combined with recombinase polymerase amplification. Therefore, by harnessing the programmability of CRISPR/Cas12a, the biosensor has the potential to detect various drug-resistant bacteria, demonstrating significant practical applicability.

Advanced diagnostic methods for identification of bacterial foodborne pathogens: contemporary and upcoming challenges

It is a public health imperative to have safe food and water across the population. Foodborne infections are one of the primary causes of sickness and mortality in both developed and developing countries. An estimated 100 million foodborne diseases and 120 000 foodborne illness-related fatalities occur each year in India. Several factors affect foodborne illness, such as improper farming methods, poor sanitary and hygienic conditions at all levels of the food supply chain, the lack of preventative measures in the food processing industry, the misuse of food additives, as well as improper storage and handling. In addition, chemical and microbiological combinations also play a key role in disease development. But recent disease outbreaks indicated that microbial pathogens played a major role in the development of foodborne diseases. Therefore, prompt, rapid, and accurate detection of high-risk food pathogens is extremely vital to warrant the safety of the food items. Conventional approaches for identifying foodborne pathogens are labor-intensive and cumbersome. As a result, a range of technologies for the rapid detection of foodborne bacterial pathogens have been developed. Presently, many methods are available for the instantaneous detection, identification, and monitoring of foodborne pathogens, such as nucleic acid-based methods, biosensor-based methods, and immunological-based methods. The goal of this review is to provide a complete evaluation of several existing and emerging strategies for detecting food-borne pathogens. Furthermore, this review outlines innovative methodologies and their uses in food testing, along with their existing limits and future possibilities in the detection of live pathogens in food.

The Rapid Detection of Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus via Polymerase Chain Reaction Combined with Magnetic Beads and Capillary Electrophoresis

Food safety concerns regarding foodborne pathogen contamination have gained global attention due to its significant implications. In this study, we developed a detection system utilizing a PCR array combined with an automated magnetic bead-based system and CE technology to enable the detection of three foodborne pathogens, namely Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. The results showed that our developed method could detect these pathogens at concentrations as low as 7.3 × 101, 6.7 × 102, and 6.9 × 102 cfu/mL, respectively, in the broth samples. In chicken samples, the limit of detection for these pathogens was 3.1 × 104, 3.5 × 103, and 3.9 × 102 cfu/g, respectively. The detection of these pathogens was accomplished without the necessity for sample enrichment, and the entire protocols, from sample preparation to amplicon analysis, were completed in approximately 3.5 h. Regarding the impact of the extraction method on detection capability, our study observed that an automated DNA extraction system based on the magnetic bead method demonstrated a 10-fold improvement or, at the very least, yielded similar results compared to the column-based method. These findings demonstrated that our developed model is effective in detecting low levels of these pathogens in the samples analyzed in this study. The PCR-CE method developed in this study may help monitor food safety in the future. It may also be extended to identify other foodborne pathogens across a wide range of food samples.

An experimental comparison between primer and nucleotide labelling to produce RPA-amplicons used for multiplex detection of antibiotic resistance genes

Direct labelling of amplification products using isothermal amplification is currently done most frequently by incorporating previously labelled primer. Although this method is well proven and widely used, it is not a universal solution due to some weaknesses. Alternatively, labelled nucleotides could be used, whose application and functionality have been already partially demonstrated. It remains to be determined how this method performs in comparison to traditional labelling, in particular combined with isothermal amplification methods. In this work, we show a detailed analysis of the labelling efficiency under different conditions and compare the results with the traditional primer-labelling method in the context of RPA amplification. Impressively, our results showed that using Cy5-labelled dUTPs can achieve much more efficient labelling for fragments above 200 bp, while using them for smaller fragments does not bring any relevant disadvantages, but also no major benefit. Furthermore, this work successfully demonstrate for the first time a quadruplex microarray for the detection of resistance genes using RPA and direct labelling with Cy5-dUTP as a potential application scenario. The sensitivities achieved here extend to SNP discovery for the detection of the proper blaKPC variant.

Novel next generation sequencing panel method for the multiple detection and identification of foodborne pathogens in agricultural wastewater

Detecting and identifying the origins of foodborne pathogen outbreaks is a challenging. The Next-Generation Sequencing (NGS) panel method offers a potential solution by enabling efficient screening and identification of various bacteria in one reaction. In this study, new NGS panel primer sets that target 18 specific virulence factor genes from six target pathogens (Bacillus cereus, Yersinia enterocolitica, Staphylococcus aureus, Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus) were developed and optimized. The primer sets were validated for specificity and selectivity through singleplex PCR, confirming the expected amplicon size. Crosscheck and multiplex PCR showed no interference in the primer set or pathogenic DNA mixture. The NGS panel analysis of spiked water samples detected all 18 target genes in a single reaction, with pathogen concentrations ranging from 10⁸ to 10⁵ colony-forming units (CFUs) per target pathogen. Notably, the total sequence read counts from the virulence factor genes showed a positive association with the CFUs per target pathogen. However, the method exhibited relatively low sensitivity and occasional false positive results at low pathogen concentrations of 10⁵ CFUs. To validate the detection and identification results, two sets of quantitative real-time PCR (qPCR) analyses were independently performed on the same spiked water samples, yielding almost the same efficiency and specificity compared to the NGS panel analysis. Comparative statistical analysis and Spearman correlation analysis further supported the similarity of the results by showing a negative association between the NGS panel sequence read counts and qPCR cycle threshold (Ct) values. To enhance NGS panel analysis for better detection, optimization of primer sets and real-time NGS sequencing technology are essential. Nonetheless, this study provides valuable insights into applying NGS panel analysis for multiple foodborne pathogen detection, emphasizing its potential in ensuring food safety.

FRET-Based Single-Molecule Detection of Pathogen Protein IsdA Using Computationally Selected Aptamers

Iron-regulated surface determinant protein A (IsdA) is a key surface protein found in the foodborne bacteria─Staphylococcus aureus (S. aureus)─which is known to be critical for bacterial survival and colonization. S. aureus is pathogenic and has been linked to foodborne diseases; thus, early detection is critical to prevent diseases caused by this bacterium. Despite IsdA being a specific marker for S. aureus and several detection methods have been developed for sensitive detection of this bacteria such as cell culture, nucleic acids amplification, and other colorimetric and electrochemical methods, the detection of S. aureus through IsdA is underdeveloped. Here, by combining computational generation of target-guided aptamers and fluorescence resonance energy transfer (FRET)-based single-molecule analysis, we presented a widely applicable and robust detection method for IsdA. Three different RNA aptamers specific to the IsdA protein were identified and their ability to switch a FRET construct to a high-FRET state in the presence of protein was verified. The presented approach demonstrated the detection of IsdA down to picomolar levels (×10^-12 M, equivalent to ∼1.1 femtomoles IsdA) with a dynamic range extending to ∼40 nM. The FRET-based single-molecule technique that we reported here is capable of detecting the foodborne pathogen protein IsdA with high sensitivity and specificity and has a broader application in the food industry and aptamer-based sensing field by enabling quantitative detection of a wide range of pathogen proteins.

Current and emerging trends in techniques for plant pathogen detection

Plant pathogenic microorganisms cause substantial yield losses in several economically important crops, resulting in economic and social adversity. The spread of such plant pathogens and the emergence of new diseases is facilitated by human practices such as monoculture farming and global trade. Therefore, the early detection and identification of pathogens is of utmost importance to reduce the associated agricultural losses. In this review, techniques that are currently available to detect plant pathogens are discussed, including culture-based, PCR-based, sequencing-based, and immunology-based techniques. Their working principles are explained, followed by an overview of the main advantages and disadvantages, and examples of their use in plant pathogen detection. In addition to the more conventional and commonly used techniques, we also point to some recent evolutions in the field of plant pathogen detection. The potential use of point-of-care devices, including biosensors, have gained in popularity. These devices can provide fast analysis, are easy to use, and most importantly can be used for on-site diagnosis, allowing the farmers to take rapid disease management decisions.

Accurate and non-destructive monitoring of mold contamination in foodstuffs based on whole-cell biosensor array coupling with machine-learning prediction models

Mold contamination in foodstuffs causes huge economic losses, quality deterioration and mycotoxin production. Thus, non-destructive and accurate monitoring of mold occurrence in foodstuffs is highly required. We proposed a novel whole-cell biosensor array to monitor pre-mold events in foodstuffs. Firstly, 3 volatile markers ethyl propionate, 1-methyl-1 H-pyrrole and 2,3-butanediol were identified from pre-mold peanuts using gas chromatography-mass spectrometry. Together with other 3 frequently-reported volatiles from Aspergillus flavus infection, the volatiles at subinhibitory concentrations induced significant but differential response patterns from 14 stress-responsive Escherichia coli promoters. Subsequently, a whole-cell biosensor array based on the 14 promoters was constructed after whole-cell immobilization in calcium alginate. To discriminate the response patterns of the whole-cell biosensor array to mold-contaminated foodstuffs, optimal classifiers were determined by comparing 6 machine-learning algorithms. 100 % accuracy was achieved to discriminate healthy from moldy peanuts and maize, and 95 % and 98 % accuracy in discriminating pre-mold stages for infected peanuts and maize, based on random forest classifiers. 83 % accuracy was obtained to separate moldy peanuts from moldy maize by sparse partial least square determination analysis. The results demonstrated high accuracy and practicality of our method based on a whole-cell biosensor array coupling with machine-learning classifiers for mold monitoring in foodstuffs.

Detection of Salmonella Enteritidis in Milk Using Conductometric Immunosensor Coated on Polyaniline/Zinc Oxide Nanocomposite

The demand for rapid and accurate detection methods for Salmonella Enteritidis necessitates the development of highly sensitive and specific biosensors to ensure proper monitoring of food safety and quality requirements in the food sector and to secure human health. This study focused on development of a polyaniline/zinc oxide (PANI/ZnO) nanocomposite film on a gold electrode conductometric immunosensor for detection of Salmonella Enteritidis. The sensor was modified with monoclonal anti-Salmonella Enteritidis antibodies as biorecognition elements. The fabricated sensor was able to detect and quantify the target pathogen within 30 min and showed a good detection range from 10¹ to 10⁵ colony-forming units (CFU)/mL for Salmonella Enteritidis and a minimum detection limit of 6.44 CFU/mL in 0.1% peptone water. Additionally, the fabricated sensor showed good selectivity and detection limit toward the target bacterium and successfully determined Salmonella Enteritidis content in ultrahigh heat-treated skim milk samples without pretreatment of the food sample.

A Review of Modern Methods for the Detection of Foodborne Pathogens

Despite the recent advances in food preservation techniques and food safety, significant disease outbreaks linked to foodborne pathogens such as bacteria, fungi, and viruses still occur worldwide indicating that these pathogens still constitute significant risks to public health. Although extensive reviews of methods for foodborne pathogens detection exist, most are skewed towards bacteria despite the increasing relevance of other pathogens such as viruses. Therefore, this review of foodborne pathogen detection methods is holistic, focusing on pathogenic bacteria, fungi, and viruses. This review has shown that culture-based methods allied with new approaches are beneficial for the detection of foodborne pathogens. The current application of immunoassay methods, especially for bacterial and fungal toxins detection in foods, are reviewed. The use and benefits of nucleic acid-based PCR methods and next-generation sequencing-based methods for bacterial, fungal, and viral pathogens' detection and their toxins in foods are also reviewed. This review has, therefore, shown that different modern methods exist for the detection of current and emerging foodborne bacterial, fungal, and viral pathogens. It provides further evidence that the full utilization of these tools can lead to early detection and control of foodborne diseases, enhancing public health and reducing the frequency of disease outbreaks.

A Simplified Amplification-Free Strategy with Lyophilized CRISPR-CcrRNA System for Drug-Resistant Salmonella Detection

Drug resistance in pathogenic bacteria has become a major threat to global health. The misuse of antibiotics has increased the number of resistant bacteria in the absence of rapid, accurate, and cost-effective diagnostic tools. Here, an amplification-free CRISPR-Cas12a time-resolved fluorescence immunochromatographic assay (AFC-TRFIA) is used to detect drug-resistant Salmonella. Multi-locus targeting in combination crRNA (CcrRNA) is 27-fold more sensitive than a standalone crRNA system. The lyophilized CRISPR system further simplifies the operation and enables one-pot detection. Induction of nucleic acid fixation via differentially charged interactions reduced the time and cost required for flowmetric chromatography with enhanced stability. The induction of nucleic acid fixation via differentially charged interactions reduces the time and cost required for flowmetric chromatography with enhanced stability. The platform developed for the detection of drug-resistant Salmonella has an ultra-sensitive detection limit of 84 CFU mL^-1 within 30 min, with good linearity in the range of 10² -10⁶ CFU mL^-1 . In real-world applications, spiked recoveries range from 76.22% to 145.91%, with a coefficient of variation less than 10.59%. AFC-TRFIA offers a cost-effective, sensitive, and virtually equipment-independent platform for preventing foodborne illnesses, screening for drug-resistant Salmonella, and guiding clinical use.

Role of Microbial Interactions across Food-Related Bacteria on Biofilm Population and Biofilm Decontamination by a TiO2-Nanoparticle-Based Surfactant

Microbial interactions play an important role in initial cell adhesion and the endurance of biofilm toward disinfectant stresses. The present study aimed to evaluate the effect of microbial interactions on biofilm formation and the disinfecting activity of an innovative photocatalytic surfactant based on TiO₂ nanoparticles. Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli, Leuconostoc spp., Latilactobacillus sakei, Serratia liquefaciens, Serratia proteomaculans, Citrobacter freundii, Hafnia alvei, Proteus vulgaris, Pseudomonas fragi, and Brochothrix thermosphacta left to form mono- or dual-species biofilms on stainless steel (SS) coupons. The effectiveness of the photocatalytic disinfectant after 2 h of exposure under UV light on biofilm decontamination was evaluated. The effect of one parameter i.e., exposure to UV or disinfectant, was also determined. According to the obtained results, the microbial load of a mature biofilm depended on the different species or dual species that had adhered to the surface, while the presence of other species could affect the biofilm population of a specific microbe (p < 0.05). The disinfectant strengthened the antimicrobial activity of UV, as, in most cases, the remaining biofilm population was below the detection limit of the method. Moreover, the presence of more than one species affected the resistance of the biofilm cells to UV and the disinfectant (p < 0.05). In conclusion, this study confirms that microbial interactions affected biofilm formation and decontamination, and it demonstrates the effectiveness of the surfactant with the photocatalytic TiO₂ agent, suggesting that it could be an alternative agent with which to disinfect contaminated surfaces.

Shine: A novel strategy to extract specific, sensitive and well-conserved biomarkers from massive microbial genomic datasets

BACKGROUND

Concentrations of the pathogenic microorganisms' DNA in biological samples are typically low. Therefore, DNA diagnostics of common infections are costly, rarely accurate, and challenging. Limited by failing to cover updated epidemic testing samples, computational services are difficult to implement in clinical applications without complex customized settings. Furthermore, the combined biomarkers used to maintain high conservation may not be cost effective and could cause several experimental errors in many clinical settings. Given the limitations of recent developed technology, 16S rRNA is too conserved to distinguish closely related species, and mosaic plasmids are not effective as well because of their uneven distribution across prokaryotic taxa.

RESULTS

Here, we provide a computational strategy, Shine, that allows extraction of specific, sensitive and well-conserved biomarkers from massive microbial genomic datasets. Distinguished with simple concatenations with blast-based filtering, our method involves a de novo genome alignment-based pipeline to explore the original and specific repetitive biomarkers in the defined population. It can cover all members to detect newly discovered multicopy conserved species-specific or even subspecies-specific target probes and primer sets. The method has been successfully applied to a number of clinical projects and has the overwhelming advantages of automated detection of all pathogenic microorganisms without the limitations of genome annotation and incompletely assembled motifs. Using on our pipeline, users may select different configuration parameters depending on the purpose of the project for routine clinical detection practices on the website https://bioinfo.liferiver.com.cn with easy registration.

CONCLUSIONS

The proposed strategy is suitable for identifying shared phylogenetic markers while featuring low rates of false positive or false negative. This technology is suitable for the automatic design of minimal and efficient PCR primers and other types of detection probes.

The impact of osmotic stresses on the biofilm formation, immunodetection, and morphology of Aeromonas hydrophila

Aeromonas hydrophila (Ah) is a zoonotic pathogen of great importance to aquaculture and human health. This study systematically evaluated the impact of salinity, sugar, ammonia nitrogen, and nitric nitrogen levels on the fitness of Ah by using Luria-Bertani (LB) broth supplemented with different concentrations of NaCl, sucrose, NH₄Cl, urea, NaNO₂ or NaNO₃. Results showed that the static biofilm formation of Ah was higher at 28 °C compared to 37 °C (P < 0.05). At 28 °C, as the NaCl (>1 %) and sucrose levels increased, the Ah biofilm formation and the binding between Ah cells and monoclonal antibodies (mAbs, for immunodetection) decreased. Elevated ammonia nitrogen and nitric nitrogen levels generated no significant impact on Ah biofilm formation or immunodetection (P > 0.05). The expression of mAbs-targeted Omp remained unchanged under high NaCl or sucrose conditions. Further analysis showed that high sucrose conditions led to the over-expression of the extracellular polysaccharides (PS) and promoted the formation of capsule-like structures. These over-expressed PS and capsule structures might be one reason explaining the inhibited immunodetection efficacy. Results generated from this study provide crucial insights for the design of recovery and detection protocols for Ah present in food or environmental samples.

Conventional and advanced detection techniques of foodborne pathogens: A comprehensive review

Foodborne pathogens are a major public health concern and have a significant economic impact globally. From harvesting to consumption stages, food is generally contaminated by viruses, parasites, and bacteria, which causes foodborne diseases such as hemorrhagic colitis, hemolytic uremic syndrome (HUS), typhoid, acute, gastroenteritis, diarrhea, and thrombotic thrombocytopenic purpura (TTP). Hence, early detection of foodborne pathogenic microbes is essential to ensure a safe food supply and to prevent foodborne diseases. The identification of foodborne pathogens is associated with conventional (e.g., culture-based, biochemical test-based, immunological-based, and nucleic acid-based methods) and advances (e.g., hybridization-based, array-based, spectroscopy-based, and biosensor-based process) techniques. For industrial food applications, detection methods could meet parameters such as accuracy level, efficiency, quickness, specificity, sensitivity, and non-labor intensive. This review provides an overview of conventional and advanced techniques used to detect foodborne pathogens over the years. Therefore, the scientific community, policymakers, and food and agriculture industries can choose an appropriate method for better results.

One-Pot Synthesis of Enzyme and Antibody/CaHPO4 Nanoflowers for Magnetic Chemiluminescence Immunoassay of Salmonella enteritidis

In this study, through a bioinspired strategy, the horseradish peroxidase (HRP) and antibody (Ab) were co-embedded into CaHPO₄ to prepare HRP-Ab-CaHPO₄ (HAC) bifunctional hybrid nanoflowers by one-pot mild coprecipitation. The as-prepared HAC hybrid nanoflowers then were utilized as the signal tag in a magnetic chemiluminescence immunoassay for application in the detection of Salmonella enteritidis (S. enteritidis). The proposed method exhibited excellent detection performance in the linear range of 10-10⁵ CFU/mL, with the limit of detection (LOD) of 10 CFU/mL. This study indicates great potential in the sensitive detection of foodborne pathogenic bacteria in milk with this new magnetic chemiluminescence biosensing platform.

Lab-on-a-Chip Electrochemical Biosensors for Foodborne Pathogen Detection: A Review of Common Standards and Recent Progress

Foodborne pathogens are an important diagnostic target for the food, beverage, and health care industries due to their prevalence and the adverse effects they can cause to public health, food safety, and the economy. The standards that determine whether a given type of food is fit for consumption are set by governments and must be taken into account when designing a new diagnostic tool such as a biosensor platform. In order to meet these stringent detection limits, cost, and reliability standards, recent research has been focused on developing lab-on-a-chip-based approaches for detection devices that use microfluidic channels and platforms. The microfluidics-based devices are designed, developed, and used in different ways to achieve the established common standards for food pathogen testing that enable high throughput, rapid detection, low sample volume, and minimal pretreatment procedures. Combining microfluidic approaches with electrochemical biosensing could offer affordable, portable, and easy to use devices for food pathogen diagnostics. This review presents an analysis of the established common standards and the recent progress made in electrochemical sensors toward the development of future lab-on-a-chip devices that will aid 'collection-to-detection' using a single method and platform.

Development and Evaluation of a Next-Generation Sequencing Panel for the Multiple Detection and Identification of Pathogens in Fermented Foods

These days, bacterial detection methods have some limitations in sensitivity, specificity, and multiple detection. To overcome these, novel detection and identification method is necessary to be developed. Recently, NGS panel method has been suggested to screen, detect, and even identify specific foodborne pathogens in one reaction. In this study, new NGS panel primer sets were developed to target 13 specific virulence factor genes from five types of pathogenic Escherichia coli, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium, respectively. Evaluation of the primer sets using singleplex PCR, crosscheck PCR and multiplex PCR revealed high specificity and selectivity without interference of primers or genomic DNAs. Subsequent NGS panel analysis with six artificially contaminated food samples using those primer sets showed that all target genes were multi-detected in one reaction at 10⁸-10⁵ CFU of target strains. However, a few false-positive results were shown at 10⁶-10⁵ CFU. To validate this NGS panel analysis, three sets of qPCR analyses were independently performed with the same contaminated food samples, showing the similar specificity and selectivity for detection and identification. While this NGS panel still has some issues for detection and identification of specific foodborne pathogens, it has much more advantages, especially multiple detection and identification in one reaction, and it could be improved by further optimized NGS panel primer sets and even by application of a new real-time NGS sequencing technology. Therefore, this study suggests the efficiency and usability of NGS panel for rapid determination of origin strain in various foodborne outbreaks in one reaction.

Immunosensors-The Future of Pathogen Real-Time Detection

Pathogens and their toxins can cause various diseases of different severity. Some of them may be fatal, and therefore early diagnosis and suitable treatment is essential. There are numerous available methods used for their rapid screening. Conventional laboratory-based techniques such as culturing, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) are dominant. However, culturing still remains the "gold standard" for their identification. These methods have many advantages, including high sensitivity and selectivity, but also numerous limitations, such as long experiment-time, costly instrumentation, and the need for well-qualified personnel to operate the equipment. All these existing limitations are the reasons for the continuous search for a new solutions in the field of bacteria identification. For years, research has been focusing on the use of immunosensors in various types of toxin- and pathogen-detection. Compared to the conventional methods, immunosensors do not require well-trained personnel. What is more, immunosensors are quick, highly selective and sensitive, and possess the potential to significantly improve the pathogen and toxin diagnostic-processes. There is a very important potential use for them in various transport systems, where the risk of contamination by bioagents is very high. In this paper, the advances in the field of immunosensor usage in pathogenic microorganism- and toxin-detection, are described.

Rapid-format recombinant antibody-based methods for the diagnosis of Clostridioides difficile infection: Recent advances and perspectives

Clostridioides difficile, the most common cause of nosocomial diarrhea, has been continuously reported as a worldwide problem in healthcare settings. Additionally, the emergence of hypervirulent strains of C. difficile has always been a critical concern and led to continuous efforts to develop more accurate diagnostic methods for detection of this recalcitrant pathogen. Currently, the diagnosis of C. difficile infection (CDI) is based on clinical manifestations and laboratory tests for detecting the bacterium and/or its toxins, which exhibit varied sensitivity and specificity. In this regard, development of rapid diagnostic techniques based on antibodies has demonstrated promising results in both research and clinical environments. Recently, application of recombinant antibody (rAb) technologies like phage display has provided a faster and more cost-effective approach for antibody production. The application of rAbs for developing ultrasensitive diagnostic tools ranging from immunoassays to immunosensors, has allowed the researchers to introduce new platforms with high sensitivity and specificity. Additionally, DNA encoding antibodies are directly accessible in these approaches, which enables the application of antibody engineering to increase their sensitivity and specificity. Here, we review the latest studies about the antibody-based ultrasensitive diagnostic platforms for detection of C. difficile bacteria, with an emphasis on rAb technologies.

Assessment of Foodborne Bacterial Pathogens in Buffalo Raw Milk Using Polymerase Chain Reaction Based Assay

Milk is a putrescible commodity that is extremely prone to microbial contamination. Primarily, milk and dairy products are believed to be easily contaminated by pathogenic microorganisms, including Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus. The microbiological quality of raw milk and dairy products regarding foodborne pathogens is of paramount importance due to concern of human health. In this study 400 buffalo raw milk samples were screened for assessing the prevalence of L. monocytogenes, Salmonella spp., and S. aureus. This study implemented uniplex-polymerase chain reaction (u-PCR) and multiplex-polymerase chain reaction (m-PCR) assays for the fast simultaneous detection of these pathogens comparing to the conventional culturing methods. Raw milk samples were found contaminated with the prevalence of 2.2%, 4.0%, and 14.2% for L. monocytogenes, Salmonella spp., and S. aureus, respectively. These pathogens were detected with the optimized polymerase chain reaction assays after 6 h of enrichment. u-PCR and m-PCR demonstrated the limit of detection as 10⁴, 10², and 10 cells/mL after 6, 12, 18, and 24 h for each culture of the pathogens. A high sensitivity (10 colony-forming unit [CFU]/mL) of the m-PCR protocol was noted. The developed protocol is a cost-effective and rapid method for the simultaneous detection of pathogens associated with raw milk and dairy industries.

Recent Progress and Challenges on the Microfluidic Assay of Pathogenic Bacteria Using Biosensor Technology

Microfluidic technology is one of the new technologies that has been able to take advantage of the specific properties of micro and nanoliters, and by reducing the costs and duration of tests, it has been widely used in research and treatment in biology and medicine. Different materials are often processed into miniaturized chips containing channels and chambers within the microscale range. This review (containing 117 references) demonstrates the significance and application of nanofluidic biosensing of various pathogenic bacteria. The microfluidic application devices integrated with bioreceptors and advanced nanomaterials, including hyperbranched nano-polymers, carbon-based nanomaterials, hydrogels, and noble metal, was also investigated. In the present review, microfluid methods for the sensitive and selective recognition of photogenic bacteria in various biological matrices are surveyed. Further, the advantages and limitations of recognition methods on the performance and efficiency of microfluidic-based biosensing of photogenic bacteria are critically investigated. Finally, the future perspectives, research opportunities, potential, and prospects on the diagnosis of disease related to pathogenic bacteria based on microfluidic analysis of photogenic bacteria are provided.

Detection of Foodborne Pathogens in Acute Gastroenteritis Patient’s Stool Samples Using the BioFire® FilmArray® Gastrointestinal PCR Panel in the Republic of Trinidad and Tobago, West Indies

In 2009, the burden of illness study for acute gastroenteritis in Trinidad and Tobago highlighted that ~10% of stool samples tested were positive for a foodborne pathogen. The study also noted that limited laboratory screening for pathogens contributed to a lack of etiology as public health hospitals only routinely tested for Salmonella and Shigella, and sometimes for Escherichia coli and Campylobacter. To better understand the foodborne pathogens responsible for acute gastroenteritis, enhanced testing using the BioFire® FilmArray® Gastrointestinal PCR panel was used to screen diarrheal stool samples for 22 pathogens from patients in 2018. The five general public health hospitals (San Fernando, Mt. Hope, Port of Spain, Sangre Grande, and Tobago) were notified of research activities and diarrheal stool samples were collected from all acute gastroenteritis patients. A total of 66 stools were screened and ~30% of samples tested positive for a foodborne pathogen. The current study showed that a much wider range of enteric pathogens were associated with acute gastroenteritis in Trinidad and Tobago than previously reported in 2009. These findings can be used by health officials to guide appropriate interventions, as well as to provide evidence for adoption of the PCR panel detection method at public health hospitals to benefit patient care.

Present and pioneer methods of early detection of food borne pathogens

Food-borne pathogens are a severe threat to human illness and death world-wide. Researchers have reported more than 250 food-borne diseases. Most of these are infections caused by a wide variety of bacteria, viruses, and parasites. It has a significant economic impact also. Detection of pathogenic microbes is thus essential for food safety. Such identification techniques could meet the following parameters viz., the accuracy of detection techniques that are quick, efficient, economical, highly sensitive, specific, and non-labor intensive. The various available methods for detecting food pathogens are classified into different groups, each having its advantages and disadvantages. The conventional methods are usually the first choice of detection even though they are laborious. Modern techniques such as biosensors, immunological assays, and macromolecule-based (nucleic acid) methods are being developed and refined to overcome traditional methods' limitations. Early detection of pathogens and secure food safety at each stage of food processing to storage, utilizing improved methodologies are mandatory. This review summarizes the deadly food pathogens leading to significant outbreaks and discusses the importance of early detection methods and advanced detection methods in comparison.

Campylobacter Species, Microbiological Source Tracking and Risk Assessment of Bacterial pathogens

Campylobacter species continue to remain critical pathogens of public health interest. They are responsible for approximately 500 million cases of gastroenteritis per year worldwide. Infection occurs through the consumption of contaminated food and water. Microbial risk assessment and source tracking are crucial epidemiological strategies to monitor the outbreak of campylobacteriosis effectively. Various methods have been proposed for microbial source tracking and risk assessment, most of which rely on conventional microbiological techniques such as detecting fecal indicator organisms and other novel microbial source tracking methods, including library-dependent microbial source tracking and library-independent source tracking approaches. However, both the traditional and novel methods have their setbacks. For example, while the conventional techniques are associated with a poor correlation between indicator organism and pathogen presence, on the other hand, it is impractical to interpret qPCR-generated markers to establish the exact human health risks even though it can give information regarding the potential source and relative human risk. Therefore, this article provides up-to-date information on campylobacteriosis, various approaches for source attribution, and risk assessment of bacterial pathogens, including next-generation sequencing approaches such as shotgun metagenomics, which effectively answer the questions of potential pathogens are there and in what quantities.

Application of Nanopore Sequencing in the Detection of Foodborne Microorganisms

Foodborne pathogens have become the subject of intense interest because of their high incidence and mortality worldwide. In the past few decades, people have developed many methods to solve this challenge. At present, methods such as traditional microbial culture methods, nucleic acid or protein-based pathogen detection methods, and whole-genome analysis are widely used in the detection of pathogenic microorganisms in food. However, these methods are limited by time-consuming, cumbersome operations or high costs. The development of nanopore sequencing technology offers the possibility to address these shortcomings. Nanopore sequencing, a third-generation technology, has the advantages of simple operation, high sensitivity, real-time sequencing, and low turnaround time. It can be widely used in the rapid detection and serotyping of foodborne pathogens. This review article discusses foodborne diseases, the principle of nanopore sequencing technology, the application of nanopore sequencing technology in foodborne pathogens detection, as well as its development prospects.

Bacteriophage Tail Proteins as a Tool for Bacterial Pathogen Recognition—A Literature Review

In recent years, a number of bacterial detection methods have been developed to replace time-consuming culture methods. One interesting approach is to mobilize the ability of phage tail proteins to recognize and bind to bacterial hosts. In this paper, the authors provide an overview of the current methodologies in which phage proteins play major roles in detecting pathogenic bacteria. Authors focus on proteins capable of recognizing highly pathogenic strains, such as Acinetobacter baumannii, Campylobacter spp., Yersinia pestis, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus spp., Salmonella spp., and Shigella. These pathogens may be diagnosed by capture-based detection methods involving the use of phage protein-coated nanoparticles, ELISA (enzyme-linked immunosorbent assay)-based methods, or biosensors. The reviewed studies show that phage proteins are becoming an important diagnostic tool due to the discovery of new phages and the increasing knowledge of understanding the specificity and functions of phage tail proteins.

Recent Advances and Applications of Rapid Microbial Assessment from a Food Safety Perspective

Unsafe food is estimated to cause 600 million cases of foodborne disease, annually. Thus, the development of methods that could assist in the prevention of foodborne diseases is of high interest. This review summarizes the recent progress toward rapid microbial assessment through (i) spectroscopic techniques, (ii) spectral imaging techniques, (iii) biosensors and (iv) sensors designed to mimic human senses. These methods often produce complex and high-dimensional data that cannot be analyzed with conventional statistical methods. Multivariate statistics and machine learning approaches seemed to be valuable for these methods so as to "translate" measurements to microbial estimations. However, a great proportion of the models reported in the literature misuse these approaches, which may lead to models with low predictive power under generic conditions. Overall, all the methods showed great potential for rapid microbial assessment. Biosensors are closer to wide-scale implementation followed by spectroscopic techniques and then by spectral imaging techniques and sensors designed to mimic human senses.

Nuclease activity: an exploitable biomarker in bacterial infections

INTRODUCTION

In the increasingly challenging field of clinical microbiology, diagnosis is a cornerstone whose accuracy and timing are crucial for the successful management, therapy, and outcome of infectious diseases. Currently employed biomarkers of infectious diseases define the scope and limitations of diagnostic techniques. As such, expanding the biomarker catalog is crucial to address unmet needs and bring about novel diagnostic functionalities and applications.

AREAS COVERED

This review describes the extracellular nucleases of 15 relevant bacterial pathogens and discusses the potential use of nuclease activity as a diagnostic biomarker. Articles were searched for in PubMed using terms: "nuclease", "bacteria", "nuclease activity" or "biomarker". For overview sections, original and review articles between 2000 and 2019 were searched for using terms: "infections", "diagnosis", "bacterial", "burden", "challenges". Informative articles were selected.

EXPERT OPINION

Using the catalytic activity of nucleases offers new possibilities compared to established biomarkers. Nucleic acid activatable reporters in combination with different transduction platforms and delivery methods can be used to detect disease-associated nuclease activity patterns in vitro and in vivo for prognostic and diagnostic applications. Even when these patterns are not obvious or of unknown etiology, screening platforms could be used to identify new disease reporters.

Direct multiplex recombinase polymerase amplification for rapid detection of S taphylococcus aureus and P seudomonas aeruginosa in food

Food and beverage poisoning is detrimental to people's health since it can lead to fever, stomachaches, and even death. To rapidly detect the presence of foodborne pathogens, conventional PCR assays are currently widely employed. Meanwhile, isothermal PCR methods, in which the amplification reactions take place at a low and constant temperature, have lately emerged as effective and alternative means for quickly identifying pathogens in low-resource settings. Staphylococcus aureus and Pseudomonas aeruginosa are two of the most concerning foodborne bacterial infections. In this work, an isothermal PCR assay based on the Recombinase Polymerase Amplification (RPA) method was developed to simultaneously detect S. aureus and P. aeruginosa with high sensitivity and specificity. The limit of detection for multiplex RPA was 10 and 30 fg/reaction of S. aureus and P. aeruginosa genomic DNA, respectively. Furthermore, the reaction time was reduced to only 25 minutes, with a low incubation temperature of 39°C. Multiplex RPA reactions, in particular, were successful in directly identifying as low as 1 and 5 CFU/reaction of S. aureus and P. aeruginosa cells, respectively, without the need for DNA genome extraction. Moreover, the multiplex RPA reliably detected the two foodborne bacteria in milk, fruit juice, and bottled water samples. In conclusion, the direct multiplex RPA reported in this work offers a quick, easy, sensitive, and effective alternative approach for detecting the presence of S. aureus and P. aeruginosa without the requirement of a pricey instrument or highly-trained personnel.

Isothermal RNA Amplification for the Detection of Viable Pathogenic Bacteria to Estimate the Salmonella Virulence for Causing Enteritis

Viable foodborne pathogens can cause intestinal infection and food poisoning. Herein, we reported an RNA assay allowing for sensitive (close to 1 CFU and 1% viable bacteria detectable) and rapid (within 2.5 h) detection of viable pathogenic bacteria by coupling isothermal RNA amplification (nucleic acid sequence-based amplification, NASBA) with a CRISPR/Cas13a system. NASBA allowed direct amplification of 16S rRNA extracted from viable S. enterica (RNAs degrade rapidly in dead bacteria), and the specificity of amplification was ensured using Cas13a/crRNA to recognize the amplicons. We used the CRISPR/Cas13-based NASBA assay (termed cNASBA assay) to investigate the in vivo colonization and intestinal infection of S. enterica in mice. We found that S. enterica was mainly colonized at the cecum, colon, and rectum, and the severity of enteritis caused by S. enterica was determined by the number of viable S. enterica rather than the total count of S. enterica. The cNASBA assay can quantify viable S. enterica and thus can improve the accuracy of virulence estimation compared to qPCR. It shows promise as a reliable tool for monitoring pathogen contamination and biosafety control.

A rapid and ultrasensitive dual detection platform based on Cas12a for simultaneous detection of virulence and resistance genes of drug-resistant Salmonella

Accurate, sensitive, and rapid detection of Salmonella and determination of whether it carries drug resistance genes plays an important role in guiding the clinical medication of salmonellosis and laying a foundation for studying the mechanism of drug resistance transmission of Salmonella. Here, a novel nontransferable, ultrasensitive dual detection platform (Cas12a-Ddp) was developed. The round cap allowed for temporary storage of more Cas12a detection solution than flat cap, enabling one-pot assays and reducing aerosol contamination. The results were read out in dual mode by the microplate reader and UV visualization to achieve sensitive dual-target detection of the virulence genes and drug resistance genes of Salmonella simultaneously, with the possibility of onsite detection. Cas12a-Ddp was combined with multiple polymerase chain reactions and recombinase polymerase amplifications successively. An ultrasensitive dual detection limit of 1 CFU/mL was obtained without any cross-reaction within 40 min. This was an improvement of 1-2 orders of magnitude over the existing methods. Cas12a-Ddp overcame the influence of proteins and fat in liquid matrix foods. It was used for the detection of drug-resistant Salmonella in milk and skim milk powder, also with the dual detection limit of 1 CFU/mL and spiked recovery of 68.58%-158.49%. It was also used for the analysis of Salmonella resistance rate analysis. The Cas12a-Ddp provided a reliable, fast, sensitive, and practical multi-CRISPR detection platform.

Aptasensors for Staphylococcus aureus Risk Assessment in Food

Staphylococcus aureus (S. aureus) is the top ordinary pathogen causing epidemic and food poisoning. The authentication of S. aureus has great significance for pathologic diagnosis and food hygiene supervision. Various biosensor methods have been established for identification. This paper reviews the research progress of aptasensors for S. aureus detection, focusing on the classification of aptamer technologies, including optical aptasensors and electrochemical aptasensors. Furthermore, the feasibility and future challenges of S. aureus detection for aptamer assays are discussed. Combining aptasensors with nanomaterials appears to be the developing trend in aptasensors.

Ultrasensitive electrochemiluminescence sensor based on nitrogen-decorated carbon dots for Listeria monocytogenes determination using a screen-printed carbon electrode

Current method for identification of foodborne pathogens suffers from its relatively poor performance, consequently limiting its use. Herein, we first describe an ultrasensitive electrochemiluminescence (ECL) sensor based on nitrogen-decorated carbon dots (NCDs) for Listeria monocytogenes (L. monocytogenes) determination using a screen-printed carbon electrode (SPCE). Citric acid serves as carbon source, and ethylenediamine, a molecule containing nitrogen atom, is employed to synthesize CDs. Approximately 4 nm NCD with homogenous size distribution can be produced via a single step green microwave-assisted methodology. The construction of ECL sensor is initiated by the immobilization of capture antibody (Ab1) onto the carboxyl graphene (GOOH)-modified SPCE, where immunocomplexes (antigen and the NCD-labelled secondary antibody (Ab2-NCD)) are formed, resulting in a substantial increment in the ECL signal response in the presence of K₂S₂O₈. The GOOH allows direct formation of the capture antibodies and enhances the electrochemical properties. Under optimal parameters, this sensor exhibits wide linearity (2 to 1.0 × 10⁶ CFU mL^-1), high sensitivity (0.104 or 1.0 × 10^-1 CFU mL^-1) and specificity over the nontargeting studied pathogens and is successfully applied to determine L. monocytogenes in food products. These promising results together with its performance suggest that this proposed platform may serve as an alternative device to effectively control the spread of foodborne diseases.

Detection of Salmonella typhimurium ATCC 14028 in Powder Prepared Traditional Medicines Using Real-Time PCR

The detection of Salmonella typhimurium ATCC 14028 using real-time PCR on powdered traditional medicinal products was carried out in the microbiology and molecular biology testing laboratory of the Food and Drug Administration in Gorontalo. This research aims to provide a reference for alternative testing methods in testing the products of traditional powder preparations on the market. The sample consisted of 10 traditional powder preparations spiked with positive control of S. typhimurium ATCC 14028 phase 2. The method used in the study was real-time PCR analysis using the SYBR® Green method, while DNA isolation using the direct PCR method. Data analysis was performed by analyzing the sample's melting temperature (Tm) curve and comparing it with positive control. The results showed that S. typhimurium ATCC 14028 was detected in samples at an average Tm value of 84.18°C, with ranges of 84.0-84.5°C. For positive control, the Tm value was at 85.2°C, while for the negative control, the Tm value was not detected. Based on these data, it can be concluded that S. typhimurium ATCC 14028 in traditional medicine products powder preparations can be detected using real-time PCR.

A detection method of Escherichia coli O157:H7 based on immunomagnetic separation and aptamers-gold nanoparticle probe quenching Rhodamine B's fluorescence: Escherichia coli O157:H7 detection method based on IMS and Apt-AuNPs probe quenching Rho B' s fluorescence

This research aimed to detect Escherichia coli O157:H7 in milk based on immunomagnetic probe separation technology and quenching effect of gold nanoparticles to Rhodamine B. Streptavidin-modified magnetic beads (MBs) were combined with biotin-modified antibodies to capture E. coli O157:H7 specifically. Gold nanoparticle (AuNPs) was incubated with sulfhydryl-modified aptamers (SH-Aptamers) to obtain the Aptamers-AuNPs probe. After magnetic beads captured target bacteria and formed a sandwich structure with the gold nanoprobe, Rhodamine B was added into complex to obtain fluorescent signal changes. Our results demonstrated that the established method could detect E. coli O157:H7 in the range of 101-107 CFU/mL, and the limit of detection (LOD) was 0.35 CFU/mL in TBST buffer (pH = 7.4). In milk simulation samples, the LOD of this method was 1.03 CFU/mL. Our research provides a promising approach on the detection of E. coli O157:H7.

Manipulation of Host Cell Organelles by Intracellular Pathogens

Pathogenic intracellular bacteria, parasites and viruses have evolved sophisticated mechanisms to manipulate mammalian host cells to serve as niches for persistence and proliferation. The intracellular lifestyles of pathogens involve the manipulation of membrane-bound organellar compartments of host cells. In this review, we described how normal structural organization and cellular functions of endosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, or lipid droplets are targeted by microbial virulence mechanisms. We focus on the specific interactions of Salmonella, Legionella pneumophila, Rickettsia rickettsii, Chlamydia spp. and Mycobacterium tuberculosis representing intracellular bacterial pathogens, and of Plasmodium spp. and Toxoplasma gondii representing intracellular parasites. The replication strategies of various viruses, i.e., Influenza A virus, Poliovirus, Brome mosaic virus, Epstein-Barr Virus, Hepatitis C virus, severe acute respiratory syndrome virus (SARS), Dengue virus, Zika virus, and others are presented with focus on the specific manipulation of the organelle compartments. We compare the specific features of intracellular lifestyle and replication cycles, and highlight the communalities in mechanisms of manipulation deployed.

Potential applications of aptamers in veterinary science

Aptamers are small nucleic acids that fold in a three-dimensional conformation allowing them to bind specifically to a target. This target can be an organic molecule, free or carried in cells or tissues, or inorganic components, such as metal ions. Analogous to monoclonal antibodies, aptamers however have certain advantages over the latter: e.g., high specificity for their target, no to low immunogenicity and easy in vitro selection. Since their discovery more than 30 years ago, aptamers have led to various applications, although mainly restricted to basic research. This work reviews the applications of aptamers in veterinary science to date. First, we present aptamers, how they are selected and their properties, then we give examples of applications in food and environmental safety, as well as in diagnosis and medical treatment in the field of veterinary medicine. Because examples of applications in veterinary medicine are scarce, we explore the potential avenues for future applications based on discoveries made in human medicine. Aptamers may offer new possibilities for veterinarians to diagnose certain diseases—particularly infectious diseases—more rapidly or “at the patient’s bedside”. All the examples highlight the growing interest in aptamers and the premises of a potential market. Aptamers may benefit animals as well as their owners, breeders and even public health in a “One Health” approach.

Electrochemical Sensors to Detect Bacterial Foodborne Pathogens

Bacterial foodborne pathogens cause millions of illnesses each year and disproportionately impact those in developing countries. To combat these diseases and their spread, effective monitoring of foodborne pathogens is needed. Technologies to detect these microbes must be deployable at the point-of-contamination, often in nonideal environments. Electrochemical sensors are uniquely suited for field-deployable monitoring, as they are quantitative, rapid, and do not require expensive instrumentation. When combined with the inherent recognition capabilities of biomolecules, electrochemistry is unmatched for quantitative biological measurements with minimal equipment requirements. This Review is centered on recent advances in electrochemical sensors for the detection of bacterial foodborne pathogens with a specific emphasis on field-deployable platforms, as this is a key requirement of any technology that could effectively halt the spread of foodborne diseases. Innovative electrochemical sensing strategies are highlighted that demonstrate the ability of these technologies to achieve high sensitivity and large detection ranges with rapid readout. Sensing strategies are categorized on the basis of whether they incorporate biological pretreatments or biorecognition elements, and their key advantages and disadvantages are summarized. As this class of sensors continues to mature, methods to incorporate device specificity and to detect targets from complex solutions will enable the translation of these platforms from laboratory prototypes to real-world implementation.

Regenerable ZnO/GaAs Bulk Acoustic Wave Biosensor for Detection of Escherichia coli in "Complex" Biological Medium

A regenerable bulk acoustic wave (BAW) biosensor is developed for the rapid, label-free and selective detection of Escherichia coli in liquid media. The geometry of the biosensor consists of a GaAs membrane coated with a thin film of piezoelectric ZnO on its top surface. A pair of electrodes deposited on the ZnO film allows the generation of BAWs by lateral field excitation. The back surface of the membrane is functionalized with alkanethiol self-assembled monolayers and antibodies against E. coli. The antibody immobilization was investigated as a function of the concentration of antibody suspensions, their pH and incubation time, designed to optimize the immunocapture of bacteria. The performance of the biosensor was evaluated by detection tests in different environments for bacterial suspensions ranging between 10³ and 10⁸ CFU/mL. A linear dependence between the frequency response and the logarithm of E. coli concentration was observed for suspensions ranging between 10³ and 10⁷ CFU/mL, with the limit of detection of the biosensor estimated at 10³ CFU/mL. The 5-fold regeneration and excellent selectivity towards E. coli detected at 10⁴ CFU/mL in a suspension tinted with Bacillus subtilis at 10⁶ CFU/mL illustrate the biosensor potential for the attractive operation in complex biological media.