Preparation of a 96-microwell plate DNA diagnostic chip for detection of foodborne bacteria and its application in an incident of food poisoning / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a 96-microwell plate DNA diagnostic chip for simultaneous detection of 9 major foodborne bacteria.</p><p><b>METHODS</b>Type-specific PCR primers labeled with biotin and oligonucleotide probes were designed according to the conservative genes of 9 major foodborne bacteria Staphylococcus aureus, Salmonella spp., Escherichia coli O157:H7 (Stx1 and Stx2), Shigella spp., Listeria monocytogenes, Bacillus cereus, Yersinia enterocolitica, Vibrio cholerae and Vibrio parahaemolyticus. A one-tube multiplex PCR system for simultaneous amplification of these bacteria was established, and the DNA probes were spotted and immobilized in the wells of the plate in 5x5 array format. Stable hybridization system between PCR products and oligonucleotide probes in the microwell was established after condition optimization. Alkaline phosphatase-conjugated streptavidin and NBT/BCIP were used to detect the hybridized PCR products.</p><p><b>RESULTS</b>Twenty standard bacteria strains were used to validate the 96 microwell plate DNA diagnostic chip and highly specific and stable experiment results were obtained. Using this chip assay, the causal pathogen Staphylococcus aureus was identified within 12 h after the sampling from an incident of food poisoning, and the result was consistent with that obtained using conventional bacterial culture and biochemical identification.</p><p><b>CONCLUSION</b>The novel 96 microwell plate DNA diagnostic chip allows rapid, accurate, automated and high-throughput bacterial detection and is especially valuable for quick response to such public health emergencies as food poisoning.</p>

One-step multiplex RT-PCR for rapid screening of type A, B and novel A (H1N1) influenza viruses / 南方医科大学学报

<p><b>OBJECTIVE</b>To developed a multiplex RT-PCR assay for simultaneous screening of type A, B and novel A (H1N1) influenza viruses.</p><p><b>METHODS</b>Two pairs of universal primers in were designed for amplifying the M gene and NS gene of type A and B influenza viruses, respectively. A pair of specific primers of HA gene was designed to detect novel A (H1N1) influenza virus. A one-step method was used to establish the multiplex RT-PCR system. A blinded experiment was carried out to validate the accuracy of this assay in comparison with the results of real-time fluorescence RT-PCR. The clinical practicability and efficacy of this assay was also evaluated.</p><p><b>RESULTS</b>The RT-PCR products were analyzed using agarose gel electrophoresis, which yielded distinct bands of the target fragments without non-specific reactions, suggesting the high efficiency and specificity of the multiplex RT-PCR. Blinded study of 50 samples demonstrated a concordance rate of 100%.</p><p><b>CONCLUSION</b>This multiplex RT-PCR assay allows one-step simultaneous detection of type A, B and novel A (H1N1) influenza viruses rapidly and accurately, and provides a valuable low-cost screening technique for influenza epidemic monitoring and early diagnosis.</p>