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Deoxynivalenol (DON) contaminates various complex matrices, necessitating straightforward, effective cleanup and precise detection methods. This study employed immunomagnetic beads for sample purification and utilized a competitive time-resolved fluoro-immuno-chromatographic assay to achieve quantitative detection of DON in corn and its by-products. The limits of detection and quantification were 104 μg/kg and 243 μg/kg, respectively. Significant cross-reactivity was absent with most common toxins, except for 3-acetyl-deoxynivalenol, which exhibited a cross-reaction rate of 3167%. The recovery rates ranged from 86% to 117%, with coefficients of variation between 6.9% and 9.5%. The correlation coefficient with HPLC was 0.977. This method is rapid, accurate, and requires no large-scale equipment, facilitating on-site detection directly. [ABSTRACT FROM AUTHOR]

Paxilline (PAX) is a tremorgenic mycotoxin that is thought to be associated with various syndromes in animals. To facilitate the determination of this toxin, a hapten was chemically synthesized and then respectively conjugated to Bovine Thyroglobulin (BTG) and Bovine serum albumin (BSA) for antibody production. Monoclonal antibody (mAb) 4F8 was finally obtained and used to establish an accurate and sensitive indirect competitive ELISA (icELISA). Various parameters that could impact the performance of icELISA were optimized, including the ion concentration, pH value and organic solvent. Under optimal condition, this assay exhibits an IC50 value as low as 0.84 µg L−1. The limit of detection (LOD) of the established icELISA method for PAX was 0.03–0.3 µg L−1. In conclusion, this study provided a rapid, sensitive, and high-throughput immunoassay for the detection of PAX in grains. [ABSTRACT FROM AUTHOR]

This study aimed to establish a time-resolved fluorescence immunoassay method for the simultaneous quantitative detection of fumonisin B1, B2 and B3 in corn. The EDC/NHS active ester method was used to prepare time-resolved fluorescent microspheres and fumonisin antibody conjugates. Fumonisin antigen was immobilized on a nitrocellulose membrane as the test line. By optimizing the number of test line, a competitive immunoassay method for detecting fumonisin was eventually established. Subsequently, the sensitivity, specificity, accuracy, precision, and correlation with the national standard method were evaluated for the established method. The detection limits of the established method by using two test line pattern were 107.68-168.28 μg/kg, and the quantification limits were 283.46-444.63 μg/kg. The cross-reactivity with fumonisin B1, fumonisin B2 and fumonisin B3 were 100%, 85.59% and 72.72%, respectively, and no significant cross-reactivity was observed with five other common mycotoxins. The recovery rates ranged from 88.37% to 117.42%, and the coefficients of variation were lower than 10%. The conformity of the results obtained by the established method, as compared to the immunoaffinity column purification-high performance liquid chromatography (IAC-HPLC) method specified in the national standard GB 5009.240-2016, fell within the range of 92.17% to 107.21%. The established time-resolved fluorescence immunoassay method meets the requirements for rapid on-site quantitative detection of fumonisin B1, B2 and B3 in corn. [ABSTRACT FROM AUTHOR]

The article discusses the integration of the Six Thinking Hats parallel thinking framework into the problem-based learning (PBL) approach among pathophysiology students to aid in their problem solving.

Objectives: This study was conducted to examine the development and molecular mechanisms of amphenicol resistance in Campylobacter jejuni by using in vitro selection with chloramphenicol and florfenicol. The impact of the resistance development on growth rates was also determined using in vitro culture. Methods: Chloramphenicol and florfenicol were used as selection agents to perform in vitro stepwise selection. Mutants resistant to the selective agents were obtained from the selection process. The mutant strains were compared with the parent strain for changes in MICs and growth rates. The 23S rRNA gene and the L4 and L22 ribosomal protein genes in the mutant strains and the parent strain were amplified and sequenced to identify potential resistance-associated mutations. Results: C. jejuni strains that were highly resistant to chloramphenicol and florfenicol were obtained from in vitro selection. A novel G2073A mutation in all three copies of the 23S rRNA gene was identified in all the resistant mutants examined, which showed resistance to both chloramphenicol and florfenicol. In addition, all the mutants selected by chloramphenicol also exhibited the G74D modification in ribosomal protein L4, which was previously shown to confer a low-level erythromycin resistance in Campylobacter species. The mutants selected by florfenicol did not have the G74D mutation in L4. Notably, the amphenicol-resistant mutants also exhibited reduced susceptibility to erythromycin, suggesting that the selection resulted in cross resistance to macrolides. Conclusions: This study identifies a novel point mutation (G2073A) in 23S rRNA in amphenicol-selected mutants of C. jejuni. Development of amphenicol resistance in Campylobacter likely incurs a fitness cost as the mutant strains showed slower growth rates in antibiotic-free media. [ABSTRACT FROM AUTHOR]

Objectives: This study was conducted to examine the development and molecular mechanisms of amphenicol resistance in Campylobacter jejuni by using in vitro selection with chloramphenicol and florfenicol. The impact of the resistance development on growth rates was also determined using in vitro culture. Methods: Chloramphenicol and florfenicol were used as selection agents to perform in vitro stepwise selection. Mutants resistant to the selective agents were obtained from the selection process. The mutant strains were compared with the parent strain for changes in MICs and growth rates. The 23S rRNA gene and the L4 and L22 ribosomal protein genes in the mutant strains and the parent strain were amplified and sequenced to identify potential resistance-associated mutations. Results: C. jejuni strains that were highly resistant to chloramphenicol and florfenicol were obtained from in vitro selection. A novel G2073A mutation in all three copies of the 23S rRNA gene was identified in all the resistant mutants examined, which showed resistance to both chloramphenicol and florfenicol. In addition, all the mutants selected by chloramphenicol also exhibited the G74D modification in ribosomal protein L4, which was previously shown to confer a low-level erythromycin resistance in Campylobacter species. The mutants selected by florfenicol did not have the G74D mutation in L4. Notably, the amphenicol-resistant mutants also exhibited reduced susceptibility to erythromycin, suggesting that the selection resulted in cross resistance to macrolides. Conclusions: This study identifies a novel point mutation (G2073A) in 23S rRNA in amphenicol-selected mutants of C. jejuni. Development of amphenicol resistance in Campylobacter likely incurs a fitness cost as the mutant strains showed slower growth rates in antibiotic-free media. [ABSTRACT FROM AUTHOR]

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 ., Competing Interests: The authors declare no conflict of interest.