Assay For Identification Research Articles

Comparison of the solid-phase red cell adherence assay and tube method for detection and identification of red blood cell antibodies.

Identifying antibodies to red blood cell antigens is one of transfusion medicine's critical responsibilities. The International Society of Blood Transfusion recognizes 354 red blood cell antigens. Accurate identification of clinically significant alloantibodies is imperative for preventing hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. We compared the performance of the tube (polyethylene glycol-indirect antiglobulin test [PEG-IAT]) and solid-phase red cell adherence assay techniques. We performed a retrospective study on all antibody screens performed between 2007 and 2021 at Stanford Transfusion Services. Initially, 631,535 antibody screens were performed using a solid-phase technique. Subsequent antibody identifications were performed using a combination of tube testing and solid-phase techniques. Antibody screening resulted in 28,316 (4.5%) positive samples. Antibody identification performed on both platforms identified 50 discordant samples. The anti-E antibody had the lowest sensitivity (98.99%) in the automated solid-phase technique, while anti-Jkb had the lowest sensitivity (98.78%) with the PEG-IAT method. To our knowledge, this is the first robust, 15-year study comparing methodologic sensitivity to detect clinically significant alloantibodies. The incidence of discordant results between PEG-IAT and the solid-phase technique was low. Among discordant samples, anti-Jka was commonly detected using the solid-phase method but not with the PEG-IAT. In contrast, anti-E was commonly detected by PEG-IAT but not by the solid-phase method.

A Multiplex Recombinase-Aided qPCR Assay for Highly Sensitive and Rapid Detection of khe, blaKPC -2, and blaNDM -1 Genes in Klebsiella pneumoniae.

This study aimed to establish a highly sensitive and rapid single-tube, two-stage, multiplex recombinase-aided qPCR (mRAP) assay to specifically detect the khe, blaKPC-2, and blaNDM-1 genes in Klebsiella pneumoniae. mRAP was carried out in a qPCR instrument within 1 h. The analytical sensitivities of mRAP for khe, blaKPC-2, and blaNDM-1 genes were tested using recombinant plasmids and dilutions of reference strains. A total of 137 clinical isolates and 86 sputum samples were used to validate the clinical performance of mRAP. mRAP achieved the sensitivities of 10, 8, and 14 copies/reaction for khe, blaKPC-2, and blaNDM-1 genes, respectively, superior to qPCR. The Kappa value of qPCR and mRAP for detecting khe, blaKPC-2, and blaNDM-1 genes was 1, 0.855, and 1, respectively (p < 0.05). mRAP is a rapid and highly sensitive assay for potential clinical identification of khe, blaKPC-2, and blaNDM-1 genes in K. pneumoniae.

Abstract 341: Co-detection of BCR::ABL1 common and atypical fusion and mutation using a novel NGS assay, Dup-Seq BCR-ABL1

Abstract The clinical management of CML and Ph+ ALL patients requires the identification of BCR::ABL1 transcript variants and drug resistance mutations. Currently these assessments need to be performed using separate assays resulting in higher sample requirements, longer turnaround times and higher costs. In this study a custom NGS assay (Dup-Seq BCR-ABL1) was developed and validated that enables co-detection and identification of transcript variants (common and atypical) and resistance mutations. The assay design covers BCR exon 1 to ABL1 exon 10 and employs duplicate PCR amplification of BCR-ABL1 from a single source of the 1st strand cDNA initiated by ABL1 specific priming. The custom data analysis pipeline enables overlapped mutation calling from duplicates as well as transcript determination. The assay minimizes the low-level artifacts that can be seen with other NGS-based BCR::ABL1 assays. This study demonstrates that the Dup-Seq BCR-ABL1 assay achieves high accuracy (PPA for fusion: 0.985; PPA and NPA for mutation at 0.978 and 0.9999, respectively) and sensitivity (LoD for mutation detection at 3% from 10,000 copies of BCR-ABL1 input). The use of the Dup-Seq BCR-ABL1 assay for both transcript variant identification and mutation detection provides comprehensive and accurate results for the clinical management of CML and Ph+ ALL patients while reducing sample requirements, testing costs and turnaround time. Citation Format: Jin Li, Zhenyu Yan, Lin Shi, Wei Li, Weihua Liu, Cynthia Spittle, Chad Galderisi. Co-detection of BCR::ABL1 common and atypical fusion and mutation using a novel NGS assay, Dup-Seq BCR-ABL1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 341.

Abstract 3758: Evaluation of breast cancer-derived extracellular vesicles as diagnostic indicator for HER2 status

Abstract HER2-low is a new distinct type of breast cancer that is characterized by low levels of the HER2 protein. As treatment paradigms for HER2-low breast cancer are rapidly evolving with the approval of antibody-drug conjugates, identification of HER2-low breast cancer with more sensitive and reproducible HER2 assays is needed. We aimed to investigate the utility of liquid biopsy in isolating tumor-derived extracellular vesicles (TDEs) for diagnosis of HER2 status. We adopted an affinity-based approach to isolate TDEs and performed CNV analysis of the ERBB2/neu genes using the tumor DNA present in TDEs (etDNA). HER2 status of etDNA had been determined by droplet digital PCR using HER2/EIF2C ratio, a highly accurate method to quantify DNA copy number. In our study, we utilized a variety of breast cancer cell lines categorized as HER2-low (MDA-MB-231, MCF7, ZR-75-1) and HER2-high (MDA-MB-453, BT-474, SK-BR-3) to confirm HER2 expression in extracellular vesicles (EVs) by flow cytometry. This analysis successfully demonstrated that EVs effectively reflect the HER2 status of the tumor cells, evidenced by a strong Pearson correlation coefficient (r=0.987, p&amp;lt;0.001). Further clinical validation was conducted with plasma samples from 22 breast cancer patients. In the clinical study, we observed a significant correlation between the CNV of tumor DNA present in TDEs and the HER2 status of primary tumors (p&amp;lt;0.01). Additionally, the Receiver Operating Characteristic (ROC) analysis yielded an impressive area under the curve (AUC) value of 0.838 (p&amp;lt;0.01), demonstrating a high level of accuracy in differentiating between high and low HER2 groups, with a sensitivity of 55.6% and a specificity of 100%. In summary, we show potential diagnostic tools for real-time, less invasive determination of HER2 status in primary tumors, providing continuous monitoring methods for HER2 status. Although further validation in larger cohorts and prospective studies is needed, our study indicates that TDE analysis could contribute to the assays for identification of the HER2 status in breast cancer patients. Citation Format: Sol Moon, Min Woo Kim, Young Kim, Suji Lee, Hyojung Lee, Joon Ye Kim, Seung Il Kim, Jee Ye Kim. Evaluation of breast cancer-derived extracellular vesicles as diagnostic indicator for HER2 status [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3758.

Abstract 3671: Analytical performance of the Oncomine™ Dx Express Test, a CE-IVD NGS liquid biopsy assay for identification of clinically relevant variants

Abstract For in vitro Diagnostic use only. Not available in all regions including the United States. Introduction Minimally invasive blood-based liquid biopsy using cell-free total nucleic acid (cfTNA) and next generation sequencing (NGS) has substantially evolved in the field of clinical diagnostics for oncology, for detection of molecular therapeutic targets in non-small cell lung cancer (NSCLC). Here we describe analytical validation results for cfTNA using the CE-IVD Oncomine™ Dx Express Test (ODxET) assay, a qualitative in vitro diagnostic test that uses targeted NGS technology, the Ion Torrent Genexus™ Dx Integrated Sequencer to detect SNV, indel and copy number gain present in 42 genes and fusions in 7 genes from cfTNA isolated from NSCLC plasma samples. Methods Plasma samples from NSCLC patients were screened for variants of interest on several important gene loci. Screening involved isolation of cfTNA from K2-EDTA-derived plasma using the Genexus™ Cell-Free Total Nucleic Acid Purification kit on an automated purification system and sequencing was performed on the Genexus™ Dx integrated sequencer using the ODxET assay. Plasma samples having clinically relevant variants from the set of screened plasma samples were used to perform the validation studies. Results Analytical sensitivity and specificity of NSCLC plasma samples were characterized through determination of limit of detection (LOD) and limit of blank (LOB), respectively. The LOD level tested for DNA SNVs, and indels at 5 ng (minimum) input level ranged from 0.62% to 1.82% allelic frequency (AF), while 30 ng (maximum) input shows the LOD level ranging from 0.23% to 0.42% AF. The LOD for the tested RNA fusions ranged from 4.2 to 19.6 molecular counts for 5ng input and 4.9 to 8.0 molecular counts for 30ng input. Furthermore, LOB for the ODxET assay was determined by testing wild type (WT) cfTNA extracted from 30 healthy donor blood plasma samples, which were confirmed to be negative at all variant locations. The analytical accuracy study shows the false positive rate at 0.20% for SNVs, 0% for indel locations and fusion targets. In addition, the analytical reproducibility study shows 99.64% intra-run repeatability call rate for DNA variants and 98.75% for RNA variants. Conclusion In conclusion, we establish that the ODxET assay on Ion Torrent Genexus Dx Integrated Sequencer, is fast and efficient while demonstrating high sensitivity, specificity, and reproducibility for testing NSCLC liquid biopsy samples. Citation Format: Madhuri Jasti, Swasti Raut, Diarra Hassell, Nader Ezzedine, Daniela Garcia, Stephen Wunsch, Nick Siepert, Elliott Martinez, Emilia Ostrowska, Jeff Schagemann, Jian Gu, Thilanka Jayaweera, Luming He, Angie Cheng. Analytical performance of the Oncomine™ Dx Express Test, a CE-IVD NGS liquid biopsy assay for identification of clinically relevant variants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3671.

A rapid and field-ready snap-chill polymerase spiral reaction (PSR) colorimetric assay for identification of buffalo (Bubalus bubalus) tissue

The present study introduces a novel Point-of-Care (POC) polymerase spiral reaction (PSR) assay for rapid, on-site buffalo tissue identification, particularly in resource-constrained settings. Polymerase spiral reaction addresses the limitations of existing detection methods by utilizing chemical-free snap-chill DNA extraction, highly specific mitochondrial d-loop gene primers for amplification, and a unique chromogenic indicator triad of hydroxy naphthol blue, malachite green, and phenol red for visual detection. The effectiveness of the chromogenic indicators was validated against SYBR Green I and agarose gel electrophoresis methods. The assay exhibits high specificity with no cross-amplification observed in common meats (beef, mutton, chevon, and pork), sensitivity down to 10 fg of buffalo DNA, and the ability to detect adulteration as low as 0.1% buffalo meat content. Comprehensive validation through diverse, blind, and processed samples, along with established compatibility with the commercially available DNA isolation kit and comparison with standard buffalo-specific PCR, confirms its accuracy. To the best of our knowledge, this represents the first report of a PSR colorimetric assay capable of identifying buffalo tissue within 90 min in resource-constrained settings.

O121: Advancing Surgical Innovations: A Novel Approach to Engineering an Off-The-Shelf Bone-Tendon Junction Scaffold Suitable for Transplantation

Abstract Background Musculoskeletal injuries occurring at a staggering rate of 1.7 billion annually, frequently involve the complex bone-tendon junction (BTJ) often due to tear from tendon end due to cyclical strain. Current treatment options, varying from repair to reconstruction usually result in suboptimal outcomes due to structural inconsistencies. Methods In this novel study, we developed comprehensive approach to tackle this clinical challenge. We subjected BTJ tissue harvested from rabbit lower limbs (N=22) to decellularisation process. This involved 5-day demineralisation with 5% formic acid, followed by 8-day proprietary decellularisation method. Further, decellularised bone segments were immersed in Ca-P simulated body fluid for 24 hours to achieve mineral phase and enhance cell attachment. To facilitate recellularisation, adipose-derived stem cells were cultured in differentiating media for 14 days, differentiating into osteoblasts and fibroblasts for bone and tendon segments respectively. Cell phenotype was characterised using cell identification assays. Precise injection of differentiated cells into respective segments was conducted under cyclical mechanical loading with innovative stepper motor device, simulating native tissue physiology. Results Confirmation of effective decellularisation was established through histological characterisation and DNA quantification, with DNA content reduced to &amp;lt;50ng/mg (p&amp;lt;0.05) in bone segment. Successful recellularisation of decellularised scaffold and cell alignment in direction of mechanical load was confirmed through histological analysis on day 5. Comparative analysis revealed similarities in properties between control, remineralised, and recellularised bone, presenting this approach as a promising regenerative technique. Conclusion Our approach offers hope to potentially revolutionise clinical outcomes in this challenging domain by effectively replicating native tissue properties.

Quantification of β-lactamase producing bacteria in German surface waters with subsequent MALDI-TOF MS-based identification and β-lactamase activity assay

Environmental oligotrophic bacteria are suspected to be highly relevant carriers of antimicrobial resistance (AMR). However, there is a lack of validated methods for monitoring in the aquatic environment. Since extended-spectrum β-lactamases (ESBLs) play a particularly important role in the clinical sector, a culturing method based on R2A-medium spiked with different combinations of β-lactams was applied to quantify β-lactamase-producing environmental bacteria from surface waters. In German surface water samples (n = 28), oligotrophic bacteria ranging from 4.0 × 103 to 1.7 × 104 CFU per 100 mL were detected on the nutrient-poor medium spiked with 3rd generation cephalosporins and carbapenems. These numbers were 3 log10 higher compared to ESBL-producing Enterobacteriales of clinical relevance from the same water samples. A MALDI-TOF MS identification of the isolates demonstrated, that the method leads to the isolation of environmentally relevant strains with Pseudomonas, Flavobacterium, and Janthinobacterium being predominant β-lactam resistant genera. Subsequent micro-dilution antibiotic susceptibility tests (Micronaut-S test) confirmed the expression of β-lactamases. The qPCR analysis of surface waters DNA extracts showed the presence of β-lactamase genes (blaTEM, blaCMY-2, blaOXA-48, blaVIM-2, blaSHV, and blaNDM-1) at concentrations of 3.7 (±1.2) to 1.0 (±1.9) log10 gene copies per 100 mL. Overall, the results demonstrate a widespread distribution of cephalosporinase and carbapenemase enzymes in oligotrophic environmental bacteria that have to be considered as a reservoir of ARGs and contribute to the spread of antibiotic resistance.

The Interaction between ADK and SCG10 Regulate the Repair of Nerve Damage

The cytoskeleton must be remodeled during neurite outgrowth, and Superior Cervical Ganglion 10 (SCG10) plays a critical role in this process by depolymerizing Microtubules (MTs), conferring highly dynamic properties to the MTs. However, the precise mechanism of action of SCG10 in the repair of injured neurons remains largely uncertain. Using transcriptomic identification, we discovered that SCG10 expression was downregulated in neurons after Spinal Cord Injury (SCI). Additionally, through mass spectrometry identification, immunoprecipitation, and pull-down assays, we established that SCG10 could interact with Adenosine Kinase (ADK). Furthermore, we developed an excitotoxicity-induced neural injury model and discovered that ADK suppressed injured neurite re-growth, whereas, through overexpression and small molecule interference experiments, SCG10 enhanced it. Moreover, we discovered ADK to be the upstream of SCG10. More importantly, the application of the ADK inhibitor called 5-Iodotubercidin (5-ITu) was found to significantly enhance the recovery of motor function in mice with SCI. Consequently, our findings suggest that ADK plays a negative regulatory role in the repair of injured neurons. Herein, we propose a molecular interaction model of the SCG10-ADK axis to regulate neuronal recovery.

Rapid, visual, label-based biosensor platform for identification of hepatitis C virus in clinical applications

ObjectivesIn the current study, for the first time, we reported a novel HCV molecular diagnostic approach termed reverse transcription loop-mediated isothermal amplification integrated with a gold nanoparticles-based lateral flow biosensor (RT-LAMP-AuNPs-LFB), which we developed for rapid, sensitive, specific, simple, and visual identification of HCV.MethodsA set of LAMP primer was designed according to 5’untranslated region (5’UTR) gene from the major HCV genotypes 1b, 2a, 3b, 6a, and 3a, which are prevalent in China. The HCV-RT-LAMP-AuNPs-LFB assay conditions, including HCV-RT-LAMP reaction temperature and time were optimized. The sensitivity, specificity, and selectivity of our assay were evaluated in the current study. The feasibility of HCV-RT-LAMP-AuNPs-LFB was confirmed through clinical serum samples from patients with suspected HCV infections.ResultsAn unique set of HCV-RT-LAMP primers were successfully designed targeting on the 5’UTR gene. The optimal detection process, including crude nucleic acid extraction (approximately 5 min), RT-LAMP reaction (67℃, 30 min), and visual interpretation of AuNPs-LFB results (~ 2 min), could be performed within 40 min without specific instruments. The limit of detection was determined to be 20 copies per test. The HCV-RT-LAMP-AuNPs-LFB assay exhibited high specificity and anti-interference.ConclusionsThese preliminary results confirmed that the HCV-RT-LAMP-AuNPs-LFB assay is a sensitive, specific, rapid, visual, and cost-saving assay for identification of HCV. This diagnostic approach has great potential value for point-of-care (POC) diagnostic of HCV, especially in resource-challenged regions.

Carba PBP: a novel penicillin-binding protein-based lateral flow assay for rapid phenotypic detection of carbapenemase-producing Enterobacterales.

Rapid phenotypic detection assays, including Carba NP and its variants, are widely applied for clinical diagnosis of carbapenemase-producing Enterobacterales (CPE). However, these tests are based on the acidification of the pH indicator during carbapenem hydrolysis, which limits test sensitivity and speed, especially for the detection of CPE producing low-activity carbapenem (e.g., OXA-48 variants). Herein, we developed a novel rapid and sensitive CPE detection method (Carba PBP) that could measure substrate (meropenem) consumption based on penicillin-binding protein (PBP). Meropenem-specific PBP was used to develop a competitive lateral flow assay (LFA) for meropenem identification. For the detection of carbapenemase activity, meropenem concentration was optimized using a checkerboard assay. The performance of Carba PBP was evaluated and compared with that of Carba NP using a panel of 94 clinical strains characterized by whole-genome sequencing and carbapenem susceptibility test. The limit of detection of PBP-based LFA for meropenem identification was 7 ng mL-1. Using 10 ng mL-1 meropenem as the substrate, Carba PBP and Carba NP could detect 10 ng mL-1 carbapenemase within 25 min and 1,280 ng mL-1 CPE in 2 h, respectively. The sensitivity and specificity were 100% (75/75) and 100% (19/19) for Carba PBP and 85.3% (64/75) and 100% (19/19) for Carba NP, respectively. When compared with Carba NP, Carba PBP showed superior performance in detecting all the tested CPE strains (including OXA-48-like variants) within 25 min and presented two orders of magnitude higher analytical sensitivity, demonstrating potential for clinical diagnosis of CPE. IMPORTANCE This study successfully achieved the goal of carbapenemase activity detection with both high sensitivity and convenience, offering a convenient lateral flow assay for clinical diagnosis of carbapenemase-producing Enterobacterales.

Evaluation of the FluoroType Mycobacteria assay for identification of mycobacteria.

This study is the first clinical evaluation report of the novel FluoroType Mycobacteria assay. The assay has the potential to replace the established GenoType NTM product family in identification of culture-enriched mycobacteria. However, our research results suggest that the assay performs suboptimally and may not be feasible for use in all clinical settings.

Development of a Standardized Soybean Cyst Nematode Screening Assay in Pennycress and Identification of Resistant Germplasm.

The prospect of incorporating pennycress as an oilseed cover crop in the Midwest's corn-soybean rotation system has drawn researcher and farmer attention. The inclusion of pennycress will be beneficial as it provides an excellent soil cover to reduce soil erosion and nutrient leaching while serving as an additional source for oilseed production and income. However, pennycress is an alternative host for soybean cyst nematode (SCN), which is a major biological threat to soybean that needs to be addressed for sustainable pennycress adoption into our current production systems. To develop a standardized SCN resistance screening strategy in pennycress, we tested and optimized five parameters: (i) germination stimulants, (ii) inoculation timing, (iii) inoculation rate, (iv) experimental incubation time, and (v) susceptible checks. The standardized SCN resistance screening protocol includes the following: (i) treating pennycress seeds with gibberellic acid for 24 h, (ii) transplanting seedlings 12 to 15 days after initiating germination and inoculating 10 to 12 days after transplantation, (iii) inoculating at a rate of 1,500 eggs/100 cc soil (1,500 eggs per plant), (iv) processing roots at 30 days after inoculation, and (v) using susceptible pennycress accession Ames 32869 to calculate the female index. The standardized protocol was used to quantify the response of a diverse set of pennycress accessions for response against SCN HG type 1.2.5.7 and HG type 7. While there were no highly resistant pennycress lines identified, 15 were rated as moderately resistant to HG type 1.2.5.7, and eight were rated moderately resistant to HG type 7. The resistant lines identified in this study could be utilized to develop SCN-resistant pennycress cultivars. The study also opens a new avenue for research to understand SCN-pennycress interactions through molecular and genomic studies. This knowledge could aid in the successful inclusion of pennycress as a beneficial cover/oilseed crop in the United States Midwest.[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Development and validation of a novel multiplex digital PCR assay for identification of pathogens in cerebrospinal fluid of children with bacterial meningitis

Background and aimsIdentifying the pathogens of bacterial meningitis (BM) is crucial for its diagnosis and treatment. The aim of this study is to develop and validate a novel method for detecting pathogens in cerebrospinal fluid (CSF) of children with BM using a digital polymerase chain reaction (dPCR) assay.Materials and methods:A novel multiplex dPCR assay method has been developed and validated. The diagnostic performance of the dPCR assay was compared with that of synchronous CSF culture, and the factors affecting its performance were analyzed.Results:A total of 69 children with BM were enrolled prospectively. The sensitivity of the dPCR assay was 94.44 %, specificity was 100 %, coincidence rate was 98.55 %, Kappa value was 0.959, and net reclassification improvement was 61.11 %. Compared with the CSF culture assay, the dPCR assay had higher sensitivity in different bacterial groups. Multiple factors affected its performance, including previous use of antibiotics, sampling time, BM complications, and levels of inflammatory biomarkers in CSF and blood (all P < 0.05). Patients who required intensive care and died had a higher bacterial DNA loads identified by dPCR assay (both P < 0.05).Conclusion:This novel assay has better pathogen detection ability than CSF culture. Its performance was influenced by sampling time, previous use of antibiotics, and disease severity.

Simultaneous Differential Detection of H5, H7, H9 and Nine NA Subtypes of Avian Influenza Viruses via a GeXP Assay.

H5, H7 and H9 are the most important subtypes of avian influenza viruses (AIVs), and nine neuraminidase (NA) subtypes (N1-N9) of AIVs have been identified in poultry. A method that can simultaneously detect H5, H7, H9 and the nine NA subtypes of AIVs would save time and effort. In this study, 13 pairs of primers, including 12 pairs of subtype-specific primers for detecting particular subtypes (H5, H7, H9 and N1-N9) and one pair of universal primers for detecting all subtypes of AIVs, were designed and screened. The 13 pairs of primers were mixed in the same reaction, and the 13 target genes were simultaneously detected. A GeXP assay using all 13 pairs of primers to simultaneously detect H5, H7, H9 and the nine NA subtypes of AIVs was developed. The GeXP assay showed specific binding to the corresponding target genes for singlet and multiplex templates, and no cross-reactivity was observed between AIV subtypes and other related avian pathogens. Detection was observed even when only 102 copies of the 13 target genes were present. This study provides a high-throughput, rapid and labor-saving GeXP assay for the simultaneous rapid identification of three HA subtypes (H5, H7 and N9) and nine NA subtypes (N1-N9) of AIVs.

Stenotrophomonas maltophilia complex: insights into evolutionary relationships, global distribution and pathogenicity.

Stenotrophomonas maltophilia complex (Smc) comprises opportunistic Gram-negative bacilli responsible for various nosocomial infections. Limited data exists concerning its evolutionary lineage, global prevalence and pathogenicity. We conducted an extensive genomic analysis on 734 Smc genomes, of which 90 were newly sequenced and isolated from different patients. The species composition and evolutionary relationships of Smc were examined using core protein sequence analysis. Pathogenicity evaluation was used by assays for swimming motility, biofilm formation and identification of virulence factors. The broth microdilution method was used to evaluate the drug resistance spectrum of clinical isolates. Phylogenetic analyses delineated 24 species-level clades, dominated by S. maltophilia (42.8%), S. sepilia (13.6%) and S. geniculata (9.9%). Geographically, strains were primarily distributed in Europe (34.2%), Asia (33.7%) and North America (24.0%), with intricate global distribution patterns. Meanwhile, 154 virulence-associated genes and 46 antimicrobial resistance genes within Smc were identified. These genes encoded span various functions, including motility, adherence, toxin, RND antibiotic efflux pumps, beta-lactamases and aminoglycoside-modifying enzymes. Moreover, significant variations were indicated in swimming motility and biofilm-forming capability across the different species, with S. sepilia exhibiting superior levels of both traits. Additionally, no statistically significant discrepancy was detected among Smc species to other antibiotics, despite the fact that all S. geniculata isolates were resistant to Ceftazidime and much higher than other species. Our findings indicate the need to pay increased attention to other mainstream species of Smc besides S. maltophilia in order to better manage Smc-related infections and tailor effective treatment strategies.

Cross-pathogenicity of Phytophthora palmivora associated with bud rot disease of oil palm and development of biomarkers for detection.

Phytophthora palmivora has caused disease in many crops including oil palm in the South America region. The pathogen has had a significant economic impact on oil palm cultivation in Colombia, and therefore poses a threat to oil palm cultivation in other regions of the World, especially in Southeast Asia, the largest producer of the crop. This study aimed to look at the ability of isolates from Malaysia, Colombia, and other regions to cross-infect Malaysian oil palm, durian, and cocoa and to develop specific biomarkers and assays for identification, detection, and diagnosis of P. palmivora as a key component for the oil palm biosecurity continuum in order to contain the disease especially at the ports of entry. We have developed specific molecular biomarkers to identify and detect Phytophthora palmivora using polymerase chain reaction (PCR) and real-time loop mediated isothermal amplification (rt-LAMP) in various sample types such as soil and plants. The limit of detection (DNA template, pure culture assay) for the PCR assay is 5.94 × 10-2 ng µl-1 and for rt-LAMP is 9.28 × 10-4 ng µl-1. Diagnosis using rt-LAMP can be achieved within 30min of incubation. In addition, PCR primer pair AV3F/AV3R developed successfully distinguished the Colombian and Malaysian P. palmivora isolates.

Integrating rapid pathogen identification and antimicrobial susceptibility testing through multiplex TaqMan qPCR assay

Timely bacterial identification (ID) and antimicrobial susceptibility testing (AST) are of significance for therapy of bacteria-infected patients. In the present study, we developed a multiplex TaqMan qPCR assay for rapid and accurate ID and AST of three common hospital acquired pneumonia species, namely Acinetobacter baumannii, Klebsiella pneumoniae and Staphylococcus aureus. In this assay, DNA extraction and bacterial co-incubation with antibiotics are accomplished based on a common PCR instrument. ID of three bacteria is based on specific conserved DNA sequence fragment (gltA for A. baumannii, phoE for K. pneumoniae and nuc for S. aureus) detection through multiplex TaqMan qPCR assay within 80 min. AST of three bacteria could be acquired within 200 min based on genomic DNA fold change detection after 2 h of antibiotic exposure. Testing of 23 bronchoalveolar lavage fluid samples spiked by different A. baumannii isolates, 20 bronchoalveolar lavage fluid samples spiked by different K. pneumoniae isolates, and 14 bronchoalveolar lavage fluid samples spiked by different S. aureus isolates showed that the multiplex TaqMan qPCR assay had 100% (95% CI: 85.69–100), 100% (95% CI: 83.89–100) and 100% (95% CI:78.47–100) identification agreement with the initial spiked bacteria. Subsequent AST results compared with the standard broth microdilution method showed an overall agreement of 91.30% (95% CI: 73.20 to 97.58) for A. baumannii, 90% (95% CI: 69.90 to 97.21) for K. pneumoniae and 92.86% (95% CI: 68.53 to 98.73) for S. aureus based on the current multiplex TaqMan assay. Due to the high rapidity, good agreement, simplicity, and high throughput, this multiplex TaqMan assay could be helpful for ID and broad-spectrum AST in A. baumannii, K. pneumoniae and S. aureus, as well as potentially applicable for other clinical bacteria by changing the primers and probes.

First Report of Leaf Spot Caused by Botrytis cinerea on Strawberry in China.

In the winter of 2022, circular or irregular leaf spots were observed on strawberry (Fragaria × ananassa) planted in commercial fields (cultivar 'xuetu', 'mengzhifu') in Yinzhou, Ningbo, Zhejiang, China (N29°48'48″, E121°39'47″), with disease incidence ranging from 10 to 15% in a field approximately 0.67 ha in size. The estimated crop loss associated with this disease was ~10%. Symptoms included circular or irregular lesions with brown halos and wheel marks, which eventually developed into leaf blight and petiole decay, but spore masses were seldom found on the leaf surface. In severe cases, leaves withered and abscissed. To isolate the causal agent, ten diseased leaves from ten different plants were collected, surface-sterilized with 75% ethanol for 50 s, rinsed twice with sterile distilled water, cut into small pieces (0.5 cm × 0.5 cm), and plated on potato dextrose agar (PDA), then incubated at 25°C in darkness for 5 days. Isolates , which displayed one kind of colony morphology were consistently obtained from each of the ten samples, and 58 single-conidium isolates with the same colony morphology were obtained. The isolation frequency was 58 of 60 samples. The colonies that grew on PDA produced white mycelia, which sporulated after 1 week, producing typical Botrytis-like gray spores. Three isolates (NBCM-1, NBCM-2, NBCM-3) were selected for identification and pathogenicity assays. Conidia were round to ellipsoid, 9.2 to 14.3 μm long (n=50), and 6.4 to 9.2 μm wide (n=50). Sclerotia were not observed on PDA. Based on these characteristics, the pathogen was tentatively identified as Botrytis cinerea (Zhang 2001). PCR was conducted for each of the three isolates to amplify the G3PDH, HSP60, RPB2, NEP1, and NEP2 genes, which are typically used for molecular identification of Botrytis species (Staats et al. 2005; Liu et al. 2016). The resulting amplicons were sequenced, and the sequences were processed using BLAST in the National Center for Biotechnology Information. Sequences of the three isolates were deposited in GenBank (accession nos. OR052082 to OR052086, OR493405 to OR493414). BLASTn analyses showed that isolates were 99 to 100% identical to B.cinerea reported causing leaf spot on strawberry in California; accession numbers MK919496 (G3PDH, 883/883 bp), MK919494 (HSP60, 992/992 bp), and MK919495 (RPB2, 1081/1081 bp). The resulting concatenated data set of G3PDH-HSP60-RPB2-NEP1-NEP2 was used to conduct a multilocus phylogenetic analysis (MLSA) using the maximum likelihood method. The MLSA tree indicated that the three isolates belonged to Botrytis cinerea. To test for pathogenicity, three 1-month-old strawberry (cultivar 'xuetu') plants were inoculated with each isolate (NBCM-1, NBCM-2, NBCM-3). A noninoculated control (sterile water only) was also included. The strawberry plants were inoculated by spraying with conidia suspension (1.0 × 105/ml) until run-off. Inoculations with sterile water served as controls. All plants were kept at 28/25°C (day/night), under a 12:12-h light/dark photoperiod. All plants were covered with transparent plastic bags to maintain humidity for the first 48 h, after which the bags were removed. After 4 to 7 days, leaf spot symptoms similar to those observed in the field were observed in all inoculated plants, while the controls remained healthy. The experiment was repeated three times. The pathogen was reisolated from the inoculated leaves and again identified as B. cinerea, with the same methodology used for the initial identification. Leaf spot caused by B. cinerea on strawberry was recently reportedin California (Mansouripour and Holmes 2020) and Florida (Marin and Peres 2022). To our knowledge, this is the first report of B. cinerea causing leaf spot on strawberry in China. The pathogen is also the causal agent of Botrytis fruit rot on strawberry. Given the high variability of this pathogen (Marin and Peres 2022), further studies on its occurrence, spread, management, and control are required. The identification of this pathogen provides a basis for further research on its management and control.

Targeting NF-κB/COX-2 signaling by soyasaponin I alleviates diclofenac-induced gastric ulceration in male albino rats.

Gastric ulceration is a prevalent worldwide clinical presentation due to altered gastric defense mechanisms. Nonsteroidal anti-inflammatory drugs are one of the common causes of gastric ulcers mediated by the release of inflammatory mediators. The study aimed to investigate the potential protective effect of soyasaponin I (soya) against diclofenac (DIC)-induced gastric ulcer in rats and to highlight the underlying mechanisms. The experiment was conducted on 40 male Wistar albino rats, equally distributed into five groups: control, DIC-induced ulcer (9 mg/kg/d, orally, twice daily for 3 days), ulcer/soya-, ulcer/ranitidine-, and ulcer/soya/selective nuclear factor kappa B inhibitor (JSH-23)-treated groups. The doses of soya, ranitidine, and JSH were 20, 25, and 5 mg/kg/d, respectively, given orally. Gastric specimens were prepared for gene and histological study and for biochemical analysis of gastric prostaglandin E2 (PGE2), oxidative markers, and inflammatory cytokines. The gastric samples were formalin-fixed, paraffin-embedded, and subjected to hematoxylin and eosin (H&E), PAS staining, and immunohistochemical assay for identification of nuclear factor kappa B (NF-κB), cyclooxygenase-2 (COX-2), and proliferation marker (Ki67) expressions. The findings revealed decreased gastric PGE2 and altered inflammatory and oxidative markers in the ulcer model group. The H&E staining showed mucosal injury characterized by mucosal surface defects and inflammatory cell infiltrations. The polymerase chain reaction (PCR) and immunohistochemistry demonstrated an upregulation of NF-κB and COX-2 expression at gene/protein levels; meanwhile, Ki67 downregulation. The soya-treated group showed maintained biochemical, histological, and PCR findings comparable to the ranitidine-treated group. The JSH-23-treated group still showed partial gastric protection with biochemical and immunohistochemical changes. Soyasaponin I ameliorated DIC-induced gastric ulcers by targeting the COX-2 activity through modulation of NF-κB signaling.