7 research outputs found

    Redox-Mediated Indirect Fluorescence Immunoassay for the Detection of Disease Biomarkers Using Dopamine-Functionalized Quantum Dots

    No full text
    Here, we report a redox-mediated indirect fluorescence immunoassay (RMFIA) for the detection of the disease biomarker α-fetoprotein (AFP) using dopamine (DA)-functionalized CdSe/ZnS quantum dots (QDs). In this immunoassay, tyrosinase was conjugated with the detection antibody and acted as a bridge connecting the fluorescence signals of the QDs with the concentration of the disease biomarkers. The tyrosinase label used for RMFIA catalyzed the enzymatic oxidation of DAs on the surface of functionalized QDs and caused fluorescence quenching in the presence of the analyte. Using this technique, we obtained a limit of detection as low as 10 pM for AFP. This assay’s potential for clinical analysis was demonstrated by detecting the real sera of patients with hepatocellular carcinoma (HCC). This study makes the first use of RMFIA for the rapid detection of AFP, opening up a new pathway for the detection of disease biomarkers

    IncA/C Plasmid-Mediated Spread of CMY-2 in Multidrug-Resistant <i>Escherichia coli</i> from Food Animals in China

    No full text
    <div><p>Objectives</p><p>To obtain a broad molecular epidemiological characterization of plasmid-mediated AmpC β-lactamase CMY-2 in <i>Escherichia coli</i> isolates from food animals in China.</p><p>Methods</p><p>A total of 1083 <i>E. coli</i> isolates from feces, viscera, blood, drinking water, and sub-surface soil were examined for the presence of CMY-2 β-lactamases. CMY-2-producing isolates were characterized as follows: the <i>bla</i><sub>CMY-2</sub> genotype was determined using PCR and sequencing, characterization of the <i>bla</i><sub>CMY-2</sub> genetic environment, plasmid sizing using S1 nuclease pulsed-field gel electrophoresis (PFGE), PCR-based replicon typing, phylogenetic grouping, <i>Xba</i>I-PFGE, and multi-locus sequence typing (MLST).</p><p>Results</p><p>All 31 CMY-2 producers were only detected in feces, and presented with multidrug resistant phenotypes. All CMY-2 strains also co-harbored genes conferring resistance to other antimicrobials, including extended spectrum β-lactamases genes (<i>bla</i><sub>CTX-M-14</sub> or <i>bla</i><sub>CTX-M-55</sub>), plasmid-mediated quinolone resistance determinants (<i>qnr</i>, <i>oqxA</i>, and <i>aac-(6′)-Ib-cr</i>), <i>floR</i> and <i>rmtB</i>. The co-transferring of <i>bla</i><sub>CMY-2</sub> with <i>qnrS1</i> and <i>floR</i> (alone and together) was mainly driven by the Inc A/C type plasmid, with sizes of 160 or 200 kb. Gene cassette arrays inserted in the class 1 or class 2 integron were amplified among 12 CMY-2 producers. CMY-2 producers belonged to avirulent groups B1 (<i>n</i> = 12) and A (<i>n</i> = 11), and virulent group D (<i>n</i> = 8). There was a good correlation between phylogenetic groups and sequence types (ST). Twenty-four STs were identified, of which the ST complexes (STC) 101/B1 (<i>n</i> = 6), STC10/A (<i>n</i> = 5), and STC155/B1 (<i>n</i> = 3) were dominant.</p><p>Conclusions</p><p>CMY-2 is the dominant AmpC β-lactamase in food animals and is associated with a transferable replicon IncA/C plasmid in the STC101, STC10, and STC155 strains.</p></div

    Dendrogram of <i>Xba</i>I-PFGE patterns of CMY-producing <i>E. coli</i> strains recovered from food-producing animals.

    No full text
    <p>All the strains were CMY-2 producers, except for T19 (CMY-41) and T129 (CMY-64). Similarity analysis was performed using the Dice coefficient, and clustering was performed by following the unweighted-pair group method using average linkages (UGPMA). A total of 16 PFGE patterns were identified, and the two clusters with highly similar PFGE patterns were labeled C1 and C2. Abbreviations for the place column: SS, Sanshui; GZ, Guangzhou; KP, Kaiping; ZC, Zengcheng; PY, Panyu; MM, Maoming; QY, Qingyuan; JM, Jiangmen; ZQ, Zhaoqing; SH, Sihui. Abbreviation for PhG: Phylogenetic Group.</p
    corecore