Detection Of Pathogenic Bacteria Research Articles

Sensitive and on-Site Detection of Staphylococcus aureus Based on CRISPR/Cas 13a-Assisted Chemiluminescence Resonance Energy Transfer.

Developing a specific, sensitive, rapid, and on-site method for detecting pathogenic bacteria in food samples is critical to ensuring public safety. This article demonstrates a CRISPR/Cas13a system and a chemiluminescence resonance energy transfer (CRET) (CRISPR/Cas 13a-assisted CRET)-based strategy for sensitive and on-site detection of pathogenic bacteria in real samples. Once the hybrid double strand of aptamerS.aureus-cRNA recognizes the target model bacteria of Staphylococcus aureus (S. aureus), the released cRNA would bind with CRISPR/Cas 13a to form a complex of cRNA-CRISPR/Cas 13a, which could cleave the RNA molecule in the detecting probe of horseradish peroxidase (HRP) modified-gold nanoparticles (AuNPs) linked by RNA (AuNPs-RNA-HRP), resulting in an enhanced chemiluminescence signal due to the CRET "OFF" phenomenon after introducing the chemiluminescence substrate of luminol. The CRISPR/Cas 13a-assisted CRET strategy successfully detected S. aureus in drinking water and milk with detection limits of 20 and 30 cfu/mL, respectively, within the recovery of 90.07-105.50%. Furthermore, after integrating with an immunochromatographic test strip (ICTS), the CRISPR/Cas 13a-assisted CRET strategy achieved the on-site detection of as low as 102 cfu/mL of S. aureus in drinking water and milk via a smartphone, which is about 10 times lower than that in the previously reported AuNPs-based colorimetric ICTS, demonstrating a convenient and sensitive detection method for S. aureus in real samples.

Immobilization of a broad host range phage on the peroxidase-like Fe-MOF for colorimetric determination of multiple Salmonella enterica strains in food.

Abroad host range phage-based nanozyme (Fe-MOF@SalmpYZU47) was prepared for colorimetric detection of multiple Salmonella enterica strains. The isolation of a broad host range phage (SalmpYZU47) capable of infecting multiple S. enterica strains was achieved. Then, it was directly immobilized onto the Fe-MOF to prepare Fe-MOF@SalmpYZU47, exhibiting peroxidase-like activity. The peroxidase-like activity can be specifically inhibited by multiple S. enterica strains, benefiting from the broad host range capture ability of Fe-MOF@SalmpYZU47. Based on it, a colorimetric detection approach was developed for S. enterica in the range from 1.0 × 102 to 1.0 × 108CFUmL-1, achieving a low limit of detection (LOD) of11CFUmL-1. TheFe-MOF@SalmpYZU47 was utilized for detecting S. enterica in authentic food samples, achieving recoveries ranging from 91.88 to 105.34%. Hence, our proposed broad host range phage-based nanozyme exhibits significant potential for application in the colorimetric detection of pathogenic bacteria.

Research progress on the detection of foodborne pathogens based on aptamer recognition.

Foodborne diseases caused by bacterial contamination are a serious threat to food safety and human health. The classical plate culture method has the problems of long detection cycle, low sensitivity and specificity, and complicated operation, which cannot meet the growing demand for rapid quantitative detection of pathogenic bacteria. The frequent outbreak of foodborne diseases has put forward higher requirements for rapid and simple detection technology of foodborne pathogens. Aptamer is a kind of oligonucleotide fragment that can recognize targets with the advantages of high affinity and good specificity. The target can be range from proteins, small molecules, cells bacteria, and even viruses. Herein, the latest advances in sensitive and rapid detection of foodborne pathogens based on aptamer recognition was reviewed. Special attention has been paid to the obtained sequences of aptamers to various foodborne pathogens, the optimization of sequences, and the mechanism of aptamer recognition. Then, the research progress of biosensors for the detection of pathogenic bacteria based on aptamer recognition were summarized. Some challenges and prospects for the detection of foodborne pathogens based on aptamer recognition were prospected. In summary, with the further deepening of aptamer research and improvement of detection technology, aptamer-based recognition can meet the needs of rapid, sensitive, and accurate detection in practical applications.

Ultrasensitive and Highly Selective Detection of Staphylococcus aureus at the Single-Cell Level Using Bacteria-Imprinted Polymer and Vancomycin-Conjugated MnO2 Nanozyme.

Pathogenic bacterial infections, even at extremely low concentrations, pose significant threats to human health. However, the challenge persists in achieving high-sensitivity bacterial detection, particularly in complex samples. Herein, we present a novel sandwich-type electrochemical sensor utilizing bacteria-imprinted polymer (BIP) coupled with vancomycin-conjugated MnO2 nanozyme (Van@BSA-MnO2) for the ultrasensitive detection of pathogenic bacteria, exemplified by Staphylococcus aureus (S. aureus). The BIP, in situ prepared on the electrode surface, acts as a highly specific capture probe by replicating the surface features of S. aureus. Vancomycin (Van), known for its affinity to bacterial cell walls, is conjugated with a Bovine serum albumin (BSA)-templated MnO2 nanozyme through EDC/NHS chemistry. The resulting Van@BSA-MnO2 complex, serving as a detection probe, provides an efficient catalytic platform for signal amplification. Upon binding with the captured S. aureus, the Van@BSA-MnO2 complex catalyzes a substrate reaction, generating a current signal proportional to the target bacterial concentration. The sensor displays remarkable sensitivity, capable of detecting a single bacterial cell in a phosphate buffer solution. Even in complex milk matrices, it maintains outstanding performance, identifying S. aureus at concentrations as low as 10 CFU mL-1 without requiring intricate sample pretreatment. Moreover, the sensor demonstrates excellent selectivity, particularly in distinguishing target S. aureus from interfering bacteria of the same genus at concentrations 100-fold higher. This innovative method, employing entirely synthetic materials, provides a versatile and low-cost detection platform for Gram-positive bacteria. In comparison to existing nanozyme-based bacterial sensors with biological recognition materials, our assay offers distinct advantages, including enhanced sensitivity, ease of preparation, and cost-effectiveness, thereby holding significant promise for applications in food safety and environmental monitoring.

Detection of pathogenic bacteria in ticks from Isiolo and Kwale counties of Kenya using metagenomics.

Ticks are arachnid ectoparasites that rank second only to mosquitoes in the transmission of human diseases including bacteria responsible for anaplasmosis, ehrlichiosis, spotted fevers, and Lyme disease among other febrile illnesses. Due to the paucity of data on bacteria transmitted by ticks in Kenya, this study undertook a bacterial metagenomic-based characterization of ticks collected from Isiolo, a semi-arid pastoralist County in Eastern Kenya, and Kwale, a coastal County with a monsoon climate in the southern Kenyan border with Tanzania. A total of 2,918 ticks belonging to 3 genera and 10 species were pooled and screened in this study. Tick identification was confirmed through the sequencing of the Cytochrome C Oxidase Subunit 1 (COI) gene. Bacterial 16S rRNA gene PCR amplicons obtained from the above samples were sequenced using the MinION (Oxford Nanopore Technologies) platform. The resulting reads were demultiplexed in Porechop, followed by trimming and filtering in Trimmomatic before clustering using Qiime2-VSearch. A SILVA database pretrained naïve Bayes classifier was used to classify the Operational Taxonomic Units (OTUs) taxonomically. The bacteria of clinical interest detected in pooled tick assays were as follows: Rickettsia spp. 59.43% of pools, Coxiella burnetii 37.88%, Proteus mirabilis 5.08%, Cutibacterium acnes 6.08%, and Corynebacterium ulcerans 2.43%. These bacteria are responsible for spotted fevers, query fever (Q-fever), urinary tract infections, skin and soft tissue infections, eye infections, and diphtheria-like infections in humans, respectively. P. mirabilis, C. acnes, and C. ulcerans were detected only in Isiolo. Additionally, COI sequences allowed for the identification of Rickettsia and Coxiella species to strain levels in some of the pools. Diversity analysis revealed that the tick genera had high levels of Alpha diversity but the differences between the microbiomes of the three tick genera studied were not significant. The detection of C. acnes, commonly associated with human skin flora suggests that the ticks may have contact with humans potentially exposing them to bacterial infections. The findings in this study highlight the need for further investigation into the viability of these bacteria and the competency of ticks to transmit them. Clinicians in these high-risk areas also need to be appraised for them to include Rickettsial diseases and Q-fever as part of their differential diagnosis.

Pore-Forming Toxin-Driven Recovery of Peroxidase-Mimicking Activity in Biomass Channels for Label-Free Electrochemical Bacteria Sensing.

The development of sensitive, selective, and rapid methods to detect bacteria in complex media is essential to ensuring human health. Virulence factors, particularly pore-forming toxins (PFTs) secreted by pathogenic bacteria, play a crucial role in bacterial diseases and serve as indicators of disease severity. In this study, a nanochannel-based label-free electrochemical sensing platform was developed for the detection of specific pathogenic bacteria based on their secreted PFTs. In this design, wood substrate channels were functionalized with a Fe-based metal-organic framework (FeMOF) and then protected with a layer of phosphatidylcholine (PC)-based phospholipid membrane (PM) that serves as a peroxidase mimetic and a channel gatekeeper, respectively. Using Staphylococcus aureus (S. aureus) as the model bacteria, the PC-specific PFTs secreted by S. aureus perforate the PM layer. Now exposed to the FeMOF, uncharged 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) molecules in the electrolyte undergo oxidation to cationic products (ABTS•+). The measured transmembrane ionic current indicates the presence of S. aureus and methicillin-resistant S. aureus (MRSA) with a low detection limit of 3 cfu mL-1. Besides excellent specificity, this sensing approach exhibits satisfactory performance for the detection of target bacteria in the complex media of food.

Femtosecond laser-induced fluorescence spectroscopy for the rapid detection of pathogenic bacteria

Femtosecond laser-induced fluorescence spectroscopy for the rapid detection of pathogenic bacteria

Detection and diagnosis of bacterial pathogens in blood using laser-induced breakdown spectroscopy

The ability to rapidly and accurately detect and identify pathogenic bacteria in clinically-obtained blood specimens with laser-induced breakdown spectroscopy (LIBS) is evaluated. Samples of blood obtained from five patients in a local hospital were confirmed to be negative for the presence of bacteria by the pathology department and were then tested with LIBS. Specimens of blood were tested as obtained from the hospital with no other alteration as control samples and were also intentionally spiked with known aliquots of Escherichia coli, Staphylococcus aureus, Enterobacter cloacae, and Pseudomonas aeruginosa to simulate blood infections. LIBS spectra were acquired from blood deposited on nitrocellulose filters. The intensities of 15 emission lines measured in the spectra and 92 ratios of those line intensities were used as 107 independent variables in a partial least squares discriminant analysis (PLS-DA) to discriminate between sterile control samples and those spiked with bacteria. In addition, the entire LIBS spectrum from 200 nm – 590 nm was input into an artificial neural network analysis with principal component analysis pre-processing (PCA-ANN) to diagnose the bacterial species once detected.The PLS-DA test possessed a 96.3% sensitivity and a 98.6% specificity for the detection of pathogenic bacteria in blood when 776 spectra from 26 filters were tested by removing one entire filter at a time from the model and testing each spectrum individually. When all the spectra obtained from a filter were averaged to enhance the signal to noise of the spectrum, 19 of 19 filters of infected blood tested positive and 7 of 7 filters with sterile blood tested negative, yielding 100% sensitivity and 100% specificity. The PCA-ANN test performed on the entire LIBS spectrum possessed a 100% sensitivity and 100% specificity when using 80% of the data to build a model and withholding 20% for cross-validation testing. The same PCA-ANN performed on each of the 19 filters individually, using the other 18 filters to build the model, possessed an average sensitivity of 85.5%, an average specificity of 95.0%, and a classification accuracy of 92.5%. These results indicate the potential usefulness of LIBS for detecting and diagnosing blood infections in a clinical setting.

Detection of pathogenic bacteria in the surgical rooms of Al-Ramady hospital using next generation sequencing

This study was aimed at applying the next generation sequence technique, to evaluate the microbial contamination of the General Al-Ramady Hospital and the diagnosis of dangerous types. Several surface swabs were taken from the surgical room devices and equipment used during the surgery period at the hospital. Hospital environment contributes chiefly to the emergence of Nosocomial infection, the most common and severe complications in the provision of health care to patients in the hospital, it has become necessary to specify and identify the causes of illness through alternative methods to traditional methods that waste time, money and effort.. The results showed contamination of hospital environment by several varieties of bacteria. They were pathogenic and nonpathogenic bacteria, in spite of the action of the Antiseptics used in sterilization. the most common of which were several types of Pseudomonas of 84.26% and Acinetobacter of 13.85%. The present of this pathogenic bacteria in hospital-related injuries, which are mean vital indicators of contamination in the hospital environment. Data suggest that it is possible to diagnose and identify the types of pathogenic, discover effective strategies for monitoring and controlling the hospital environment and providing the essential tools to avoid the spread of infection, particularly in the presence of the molecular technique.

Distribution and Drug Resistance of Pathogens Causing Bloodstream Infection in Patients with Hematological Malignancies

To investigate distribution and drug resistance of pathogens of bloodstream infection in patients with hematological malignancies, in order to provide reference for clinical infection control and treatment. The clinical information of blood culture patients in the hematology department of our hospital from January 2016 to December 2021 was reviewed. They were divided into transplantation group and non-transplantation group according to whether they had undergone hematopoietic stem cell transplantation. The types of pathogens and their drug resistance were analyzed. Two hundred and ninety-nine positive strains of pathogenic bacteria were detected. In the transplantation group, Gram-negative bacteria accounted for 68.5% (50/73), Gram-positive bacteria accounted for 6.8% (5/73), and fungi accounted for 24.7% (18/73). The resistance rate of Escherichia coli to the third-generation cephalosporins was 77.8%, and 11.5% to carbapenems. The resistance rate of Klebsiella pneumoniae to the third-generation cephalosporins was 50.0%, and 56.2% to carbapenems. In the non-transplantation group, Gram-negative bacteria accounted for 64.1% (145/226), Gram-positive bacteria accounted for 31.0% (70/226), and fungi accounted for 4.9% (11/226). Gram-positive bacteria were mainly Enterococcus faecium (6.6%, 15/226) and Coagulase-negative Staphylococci (6.2%, 14/226). The fungi were all Candida tropicalis. The resistance rate of Escherichia coli to the third-generation cephalosporins was 63.8%, and 10.3% to carbapenems. The resistance rate of Klebsiella pneumoniae to the third-generation cephalosporins was 46.3%, and 26.8% to carbapenems. The types of pathogenic bacteria in bloodstream infection in patients with hematological malignancies are varied. Gram-negative bacteria is the main pathogenic bacteria. The resistance of pathogenic bacteria to antibiotics is severe. Antibiotics should be used scientifically and reasonably according to the detection and resistance of pathogenic bacteria.

Dermacentor (Indocentor) auratus Supino 1897: Potential geographic range, and medical and veterinary significance

Dermacentor (Indocentor) auratus Supino, 1897 occurs in many regions of Southeast Asia and South Asia. In many regions of Southeast Asia and South Asia, targeted tick sampling and subsequent screening of collected D. auratus ticks have detected pathogenic bacteria and viruses in D. auratus. These disease-causing pathogens that have been detected in D. auratus include Anaplasma, Bartonella, Borrelia, Rickettsia (including spotted fever group rickettsiae), African swine fever virus, Lanjan virus, and Kyasanur forest disease virus. Although D. auratus predominantly infests wild pigs, this tick is also an occasional parasite of humans and other animals. Indeed, some 91 % of human otoacariasis cases in Sri Lanka were due to infestation by D. auratus. With the propensity of this tick to feed on multiple species of hosts, including humans, and the detection of pathogenic bacteria and viruses from this tick, D. auratus is a tick of medical, veterinary, and indeed zoonotic concern. The geographic range of this tick, however, is not well known. Therefore, in the present paper, we used the species distribution model, BIOCLIM, to project the potential geographic range of D. auratus, which may aid pathogen and tick-vector surveillance. We showed that the potential geographic range of D. auratus is far wider than the current geographic distribution of this tick, and that regions in Africa, and in North and South America seem to have suitable climates for D. auratus. Interestingly, in Southeast Asia, Borneo and Philippines also have suitable climates for D. auratus, but D. auratus has not been found in these regions yet despite the apparent close proximity of these regions to Mainland Southeast Asia, where D. auratus occurs. We thus hypothesize that the geographic distribution of D. auratus is largely dependent on the movement of wild pigs and whether or not these wild pigs are able to overcome dispersal barriers. We also review the potential pathogens and the diseases that may be associated with D. auratus and provide an updated host index for this tick.

Nanofiber films based on anthocyanins for quantitative detection of pathogenic bacteria

Pathogenic microbial infections have been regarded as one of the serious factors triggering serious food poisoning and infectious disease outbreaks. Therefore, early detection of pathogenic bacteria is of great importance for food safety, environmental monitoring, and clinical diagnosis. Here, nanofiber sensing films for the visual detection of S. aureus concentrations using polyvinyl alcohol (PVA) as a substrate and anthocyanin as an indicator material were prepared by electrostatic spinning technology. To avoid the loss of dye migration and side effects on the bacteria during the contact detection method, the headspace method was used to detect the concentration of bacteria. The results show that the fiber films can monitor S. aureus at 2 × 102 cfu/mL (ΔE = 7.6) by headspace. Scatter density matrix and correlation analysis yielded that the b* value of the film was the main factor in the variation of bacterial concentrations. Combined with a support vector machine (SVM) supervised learning algorithm for non-linear data, the model was trained to accurately classify S. aureus concentrations with an accuracy of 91%, which is important for accurately controlling pathogenic bacteria and safeguarding human health.

Analysis of epidemiological characteristics and risk factors of catheter-associated urinary tract infections in patients with perineal and/or hip burns

Objective: To explore the epidemiological characteristics and risk factors of catheter-associated urinary tract infections in patients with perineal and/or hip burns. Methods: This study was a retrospective case series study. From January 2018 to December 2022, 260 patients with perineal and/or hip burns and urinary catheters indwelling who met the inclusion criteria were admitted to the Department of Burns and Wound Repair of the Second Affiliated Hospital of Zhejiang University School of Medicine, including 192 males and 68 females, aged 20-93 years. The total incidence of catheter-associated urinary tract infections in patients with perineal and/or hip burns, the detection of pathogenic bacteria, and the resistance of major Gram-negative and Gram-positive bacteria to commonly used antimicrobial drugs in clinic were recorded. According to whether catheter-associated urinary tract infection occurred or not, the patients were divided into infection group (43 cases) and non-infection group (217 cases). The basic conditions including gender, age, total burn area, depth of perineal burn, depth of hip burn, and burn site on admission, complications of diabetes mellitus, inhalation injury, and hypoproteinaemia, invasive operations including tracheotomy and non-perineal/hip debridement/skin transplantation surgery, duration of catheter retention, number of urethral catheterization, and bladder irrigation of patients between the two groups were compared, and the independent risk factors influencing the occurrence of catheter-associated urinary tract infections in patients with perineal and/or hip burns were screened. Results: The total incidence of catheter-associated urinary tract infections in patients with perineal and/or hip burns in this study was 16.5% (43/260). The pathogens detected were predominantly Gram-negative, followed by fungi; the main Gram-negative bacterium was Klebsiella pneumoniae, and the main Gram-positive bacterium was Enterococcus faecalis. The resistance rates of Klebsiella pneumoniae to amoxicillin/clavulanic acid, amitraz, amikacin, ciprofloxacin, ceftriaxone, and levofloxacin were higher than 70.0%, the resistance rates of Klebsiella pneumoniae to cefoxitin, cefoperazone/sulbactam, cefepime, meropenem, imipenem, and piperacillin/tazobactam ranged from 56.3% to 68.8%, and the resistance rates of Klebsiella pneumoniae to ceftazidime and tigecycline were lower than 50.0%. The resistance rates of Enterococcus faecalis to ciprofloxacin and penicillin were both 85.7%, the resistance rates of Enterococcus faecalis to erythromycin, clindamycin, moxifloxacin, and tetracycline ranged from 14.3% to 57.1%, and the resistance rates of Enterococcus faecalis to linezolid, tigecycline, and vancomycin were all 0. The differences were statistically significant between the two groups in terms of gender, status of complication of hypoproteinaemia, depth of perineal burn, status of non-perineal/hip debridement/skin transplantation surgery, status of bladder irrigation, number of urethral catheterization, and duration of catheter retention of patients (with χ2 values of 7.80, 4.85, 10.68, 9.11, and 16.48, respectively, and Z values of -4.88 and -5.42, respectively, P<0.05). There were no statistically significant differences in the age, total burn area, complications of diabetes mellitus and inhalation injury, burn site, depth of hip burns, and status of tracheotomy of patients between the two groups (P>0.05). Multifactorial logistic regression analysis showed that gender, deep partial-thickness perineal burns, non-perineal/hip debridement/skin transplantation surgery, bladder irrigation, and duration of catheter retention were the independent risk factors for catheter-associated urinary tract infections in patients with perineal and/or hip burns (with odds ratios of 2.86, 2.63, 2.79, 2.34, and 1.04, respectively, with 95% confidence intervals of 1.21-6.73, 1.03-6.71, 1.03-7.59, 1.05-5.22, and 1.02-1.06, respectively, P<0.05). Conclusions: The incidence of catheter-associated urinary tract infections is high in patients with perineal and/or hip burns, with Klebsiella pneumoniae as the predominant pathogenic bacteria having a high resistance rate to commonly used antimicrobial drugs in clinic. Gender, deep partial-thickness perineal burns, non-perineal/hip debridement/skin transplantation surgery, bladder irrigation, and duration of catheter retention are the independent risk factors for catheter-associated urinary tract infections in patients with perineal and/or hip burns.

Simultaneous Dual-Gene Test of Methicillin-Resistant Staphylococcus Aureus using an Argonaute-Centered Portable and Visual Biosensor.

The development of novel method for drug-resistant bacteria detection is imperative. A simultaneous dual-gene Test of methicillin-resistant Staphylococcus aureus (MRSA) is developed using an Argonaute-centered portable biosensor (STAR). This is the first report concerning Argonaute-based pathogenic bacteria detection. Simply, the species-specific mecA and nuc gene are isothermally amplified using loop-mediated isothermal amplification (LAMP) technique, followed by Argonaute-based detection enabled by its programmable, guided, sequence-specific recognition and cleavage. With the strategy, the targeted nucleic acid signals gene are dexterously converted into fluorescent signals. STAR is capable of detecting the nuc gene and mecA gene simultaneously in a single reaction. The limit of detection is 10 CFU/mL with a dynamic range from 10 to 107 CFU/mL. The sample-to-result time is <65min. This method is successfully adapted to detect clinical samples, contaminated foods, and MRSA-infected animals. This work broadens the reach of Argonaute-based biosensing and presents a novel bacterial point-of-need (PON) detection platform.

Sensitive colorimetric aptasensor for multiple foodborne pathogens detection based on PCN-Mo peroxidase-like activity

A rapid and sensitive colorimetric biosensor was developed for simultaneous detection of various pathogenic bacteria based on aptamer-mediated peroxidase (POD)-like activity of PCN-Mo nanozyme. Initially, a porphyrin-based PCN-Mo metal organic framework (MOF) nanozyme is constructed through a simple hydrothermal method, as thoroughly figured out by a series of characterization techniques. The study showed that the pathogenic bacteria aptamers could adhere to the surface of PCN-Mo, and significantly enhanced the POD-like activity by reinforcing their transport of electrons to 3,3′,5,5′-tetramethylbenzidine (TMB). In the presence of different target bacteria, the aptamers tend to bind to bacteria specifically, causing the further enhancement of POD-like activity. Based on the signal-amplification by the PCN-Mo@aptamer (PCN-Mo@Apt) nanozyme, the constructed pathogenic bacteria sensor demonstrated a wide linear range between 101 to 105 CFU/mL, with the detection limits (LODs) of 0.578, 0.439, and 0.643 CFU/mL for E. coli, S. typhimurium and S. aureus, respectively. Furthermore, the PCN-Mo sensor was capable of detection pathogenic bacteria in water, milk, classic milk tea, chicken, and beef with the recoveries of 90.1%–104.1%, indicating the sensor's practicability for pathogenic bacteria detection in real samples.

Mesoporous Silica Nanoparticles-Enhanced Microarray Technology for Highly Sensitive Simultaneous Detection of Multiplex Foodborne Pathogens.

Ensuring food safety is paramount for the food industry and global health concerns. In this study, we have developed a method for the detection of prevalent foodborne pathogenic bacteria, including Escherichia coli, Salmonella spp., Listeria spp., Shigella spp., Campylobacter spp., Clostridium spp., and Vibrio spp., utilizing antibody-aptamer arrays. To enhance the fluorescence signals on the microarray, the mesoporous silica nanoparticles (MSNs) conjugated with fluorescein, streptavidin, and seven detection antibodies-biotin were employed, forming fluorescein doped mesoporous silica nanoparticles conjugated with detection antibodies (MSNs-Flu-SA-Abs) complexes. The array pattern was designed for easy readability and enabled the simultaneous detection of all seven foodborne pathogens, referred to as the 7FP-biochip. Following the optimization of MSNs-Flu-SA-Abs complexes attachment and enhancement of the detection signal in fluorescent immunoassays, a high level of sensitivity was achieved. The detection limits for the seven pathogens in both buffer and food samples were 102 CFU/mL through visual screening, with fluorescent intensity quantification achieving levels as low as 20-34 CFU/g were achieved on the antibody-aptamer arrays. Our antibody-aptamer array offers several advantages, including significantly reduced nonspecific binding with no cross-reaction between bacteria. Importantly, our platform detection exhibited no cross-reactivity among the tested bacteria in this study. The multiplex detection of foodborne pathogens in canned tuna samples with spiked bacteria was successfully demonstrated in real food measurements. In conclusion, our study presents a promising method for detecting multiple foodborne pathogens simultaneously. With its high sensitivity and specificity, the developed antibody-aptamer array holds great potential for enhancing food safety and public health.

Development of a 3D Microfluidic Analytical Device for the Detection of Pathogenic Bacteria in Commercial Food Samples with Loop-Mediated Isothermal Amplification

Traditional methods of detecting foodborne pathogens take several days to produce the required results. Furthermore, various molecular techniques (e.g., PCR) that also produce reliable results in the detection of pathogenic bacteria have been introduced, but the cost–time ratio required does not allow them to be considered a substantial solution to this specific problem. Three-dimensional (3D) printing technology provides the ability to design and manufacture microfluidic analytical devices using conventional 3D printers, which, in combination with colorimetric loop-mediated isothermal amplification (LAMP), may further simplify the process. The overall reduction in time and cost may provide the opportunity to upscale this diagnostic modality. Moreover, unlike most microfluidic analytical devices, this technique is simpler and more user-friendly, as it does not require any expertise or additional equipment apart from a conventional oven. A 3D-printed microfluidic analytical device in combination with LAMP was developed and tested for the simultaneous detection of foodborne pathogens in food samples. A total of 150 commercial food specimens (50 milk, 50 chicken, 50 lettuce samples) were analyzed for possible contamination with Salmonella typhimurium, Listeria monocytogenes and Escherichia coli. The 3D-printed microfluidic device was 100% precise for both negative (80 samples) and positive samples (7 samples were positive for S. typhimurium, 28 for L. monocytogenes, and 35 for E. coli) for all pathogens. Overall, the amount of data analyzed led to a high level of confidence in the precision of this device. As such, this new 3D device in combination with LAMP provides a precise detection method for food pathogens with a low detection limit.

Smelly shark, smelly ray: what is infecting you?

Although elasmobranchs are consumed worldwide, bacteriological assessments for this group are still sorely lacking. In this context, this study assessed bacteria of sharks and rays from one of the most important landing ports along the Rio de Janeiro coast. Bacteria were isolated from the cloacal swabs of the sampled elasmobranchs. They were cultured, and Vibrio, Aeromonas, and Enterobacterales were isolated and identified. The isolated bacteria were then biochemically identified and antimicrobial susceptibility assays were performed. Antigenic characterizations were performed for Salmonella spp. and Polymerase Chain Reaction (PCR) assays were performed to identify Escherichia coli pathotypes. Several bacteria of interest in the One Health context were detected. The most prevalent Enterobacterales were Morganella morganii and Citrobacter freundii, while Vibrio harveyi and Vibrio fluvialis were the most prevalent among Vibrio spp. and Aeromonas allosacharophila and Aeromonas veronii bv. veronii were the most frequent among Aeromonas spp. Several bacteria also displayed antimicrobial resistance, indicative of Public Health concerns. A total of 10% of Vibrio strains were resistant to trimethoprim-sulfamethoxazole and 40% displayed intermediate resistance to cefoxitin. Salmonella enterica strains displayed intermediate resistance to ciprofloxacin, nalidixic acid and streptomycin. All V. cholerae strains were identified as non-O1/non-O139. The detected E. coli strains did not exhibit pathogenicity genes. This is the first study to perform serology assessments for S. enterica subsp. enterica isolated from elasmobranchs, identifying the zoonotic Typhimurium serovar. Salmonella serology evaluations are, therefore, paramount to identify the importance of elasmobranchs in the epidemiological salmonellosis chain. The detection of several pathogenic and antibiotic-resistant bacteria may pose significant Public Health risks in Brazil, due to high elasmobranch consumption rates, indicating the urgent need for further bacteriological assessments in this group.

Development of High-Performance and Multifunctional Nanoparticles Powered the Integrated Diagnosis and Treatment of Escherichia coli O157:H7.

Pathogenic diseases that trigger food safety remain a noteworthy concern due to substantial public health, economic, and social burdens worldwide. It is vital for developing an integrated diagnosis and treatment strategy for bacteria, which could achieve quick detection of pathogenic bacteria and the inhibition of multidrug-resistant bacteria. Herein, we reported an organic molecule (M-3) possessed strong light capture capacity, emerging a low energy gap and ΔEST. Subsequently, M-3 was integrated into a nanostructured system (BTBNPs) with excellent ROS generation, light absorption capability, and photothermal performance. Reactive oxygen species (ROS) generated by BTBNPs were mainly free radicals from a type I mechanism, and the high photothermal conversion efficiency of BTBNPs was 41.26%. Benefiting from these advantages of BTBNPs, BTBNPs could achieve a ∼99% antibacterial effect for Escherichia coli O157:H7 with 20 μM dosage and 5 min of irradiation. Furthermore, the limit of detection (LoD) of the proposed BTBNPs-LFIA (colorimetric and photothermal modalities) for detecting E. coli O157:H7 was 4105 and 419 CFU mL-1, respectively. Overall, this work is expected to provide a new and sophisticated perspective for integrated diagnosis and treatment systems regarding pathogenic bacteria.

A Method Based on a Modified Fluorescence In Situ Hybridization (FISH) Approach for the Sensing of Staphylococcus aureus from Nasal Samples.

Staphylococcus aureus is a major source of bacteremia and develops several complications, causing high morbidity and mortality. Rapid identification and detection of these bacteria have become an important issue for biomedical applications. Herein, an optical method based on a modified fluorescence in situ hybridization (FISH) approach has been established using DNA hybridization technology for the swift detection of pathogenic S. aureus from clinical samples. The platform was constructed with single-stranded genomic DNA and microbial colony by directly immobilizing in agarose-polyvinyl alcohol (AG-PVA) hydrogel on the surface of a glass slide. The probe was based on an elongation factor encoding the tuf gene, which binds with equal affinity to single-stranded DNA targets as well as surface proteins on microbial cells. The probe was labeled with MFP488 fluorophore having excitation wavelength 501nm. The hybridization of the labeled probe with the target DNA and surface proteins was carried out under optimal FISH conditions, and the detection of bacteria was based on temporary field excitation of the labeled probe under a fluorescence microscope. Positive hybridization signals were detected by high fluorescence intensity. In comparison to genomic DNA, robust signals were observed with microbial cells, perhaps due to the moonlighting effect of the elongation factor Tu (Ef-Tu) expressed on the surface of bacterial cells. The applicability of the developed platform was tested on pediatric nasal samples, and results were verified with real-time qPCR. The designed platform is stable and sensitive, and after detailed optimization, a portable structure for on-site detection of pathogenic bacteria from clinical samples can be produced.