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A novel application of GeXP analyzer was developed for simultaneous detection of six pathogens associated with food poisoning outbreaks, including Salmonella enterica, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Shigella spp., and Campylobacter jejuni. Chimeric primers containing both microbe- and pMD19-specific sequences were fused to universal sequences resulted in PCR products with intended sizes. The PCR products were separated by capillary electrophoresis and identified by using fluorescence spectrophotometry. Plasmid pMD19-T was added to each reaction as positive control to ascertain the PCR steps and data analysis step of the assay. The results indicate that the GeXP method is both specific and sensitive for the detection of all six food-borne pathogens in a single reaction-without any enrichment step. In conclusion, the GeXP-PCR assay is a rapid, sensitive and high-throughput method for parallel analysis of food-borne pathogens.

Porcine chlamydial infection is an enzootic infectious disease caused by multiple members of the family Chlamydiaceae (e.g. Chlamydophila abortus, Chlamydia suis, and Chlamydophila pneumoniae). Rapid and accurate differentiation of these pathogens is critical in the control and prevention of disease. The aim of the current study was to develop a nested multiplex polymerase chain reaction (nmPCR) assay to simultaneously detect the 3 chlamydial pathogens in clinical samples. In the first round of the nmPCR, 1 pair of family-specific primers were used to amplify the 1,100 base pair (bp) fragment of chlamydial ompA gene. In the second round of the nmPCR, 4 inner primers were designed for Ch. abortus, C. suis, and Ch. pneumoniae. Each pathogen produced a specific amplicon with a size of 340 bp, 526 bp, and 267 bp respectively. The assay was sensitive and specific for detecting target pathogens in both cell cultures and clinical specimens. The results, incorporated with the improved rapid DNA extraction protocol, suggest that the nmPCR could be a promising assay for differential identification of different chlamydial strains in pigs.