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Cai X.-Q.,Lanzhou Veterinary Research Institute | Cai X.-Q.,South China Agricultural University | Yu H.-Q.,Lanzhou Veterinary Research Institute | Yu H.-Q.,Technical Center | And 10 more authors.
Parasitology International | Year: 2012

Clonorchiasis caused by the oriental liver fluke Clonorchis sinensis is a fish-borne zoonosis endemic in a number of countries. This article describes the development of a TaqMan based real-time PCR assay for detection of C. sinensis DNA in human feces and in fishes. Primers targeting the first internal transcribed spacer (ITS-1) sequence of the fluke were highly specific for C. sinensis, as evidenced by the negative amplification of closely related trematodes in the test with the exception of Opisthorchis viverrini. The detection limit of the assay was 1. pg of purified genomic DNA, 5. EPG (eggs per gram feces) or one metacercaria per gram fish filet. The assay was evaluated by testing 22 human fecal samples and 37 fish tissues microscopically determined beforehand, and the PCR results were highly in agreement with the microscopic results. This real-time PCR assay provides a useful tool for the sensitive detection of C. sinensis DNA in human stool and aquatic samples in China and other endemic countries where O. viverrini and Opisthorchis felineus are absent. © 2011 Elsevier Ireland Ltd. Source


Zhao G.H.,Northwest University, China | Hu B.,Northwest University, China | Song J.K.,Northwest University, China | Jia Y.Q.,Northwest University, China | And 6 more authors.
Journal of Helminthology | Year: 2014

In the present study, the internal transcribed spacers (ITS) of ribosomal DNA (rDNA) of Oesophagostomum asperum and O. columbianum were amplified and sequenced. The ITS-1, 5.8S and ITS-2 rDNA sequences of O. asperum were 374Â bp, 153Â bp and 259Â bp in length, respectively, and the corresponding sequences of O. columbianum were 259, 153 and 218Â bp in length, respectively. Sequence differences in the ITS-1 and ITS-2 rDNA between the two Oesophagostomum species were 9.5-10.2% and 12.7-13.9%, respectively. Sequence differences in the ITS-1 and ITS-2 rDNA among members of the genus Oesophagostomum were 2.5-11.6% and 6.8-22.3%, respectively. Based on genetic markers in the ITS rDNA, an effective polymerase chain reaction (PCR) approach was developed to differentiate O. columbianum from O. asperum with a sensitivity of 0.2Â ng/μl DNA. Since accurate characterization of parasites at different taxonomic levels is essential for population genetic studies and control of parasitosis, the present findings have important implications for studying epidemiology, taxonomy and population biology, as well as for the control of oesophagostomiasis. © Cambridge University Press 2012. Source


Cai X.-Q.,Chinese Academy of Agricultural Sciences | Cai X.-Q.,Technical Center | Yu H.-Q.,Technical Center | Ruan Z.-X.,Animal and Plant Inspection and Quarantine Technical Center | And 8 more authors.
PLoS ONE | Year: 2013

Cronobacter spp. is an emerging pathogen that causes meningitis, sepsis, bacteremia, and necrotizing enterocolitis in neonates and children. The present study developed an assay integrating real-time PCR and high resolution melting (HRM) analysis targeting the OmpA gene for the specific detection and rapid identification of Cronobacter spp. (formerly Enterobacter sakazakii) in powdered infant formula. Eleven Cronobacter field isolates and 25 reference strains were examined using one pair of primers, having the accuracy of 100% in reference to conventional methods. The assay was proved to be highly sensitive with a detection limit of 102 CFU/ml without pre-enrichment, and highly concordant (100%) when compared with ISO-IDF 22964 in 89 actual samples. The method performed for Cronobacter spp. detection was less than 24 h, drastically shortened, compared to several days using standard culturing method, it is probe-free and reduces a risk of PCR carryover. Moreover, all Cronobacter strains examined in this study were genotyped into two species according to their HRM profiles. The established method should provide a molecular tool for direct detection and simultaneous genotyping of Cronobacter spp. in powdered infant formula. © 2013 Cai et al. Source


He J.-H.,South China University of Technology | Xu D.-Y.,South China University of Technology | Liu X.-Y.,Guangzhou Airport Entry Exit Inspection and Quarantine Bureau | Shi L.,South China University of Technology | And 2 more authors.
Modern Food Science and Technology | Year: 2013

To determine the prevalence of cadmium resistance among food-borne Listeria monocytogenes isolates of different serotypes and to know whether there are possible associations between cadmium resistance and antibiotic resistance of these isolates, all isolates were tested for their resistance to cadmium by agar dilution method. Results showed that, among 73 isolates, 36 cadmium-resistant strains were detected, the overall resistance ratio was 49.3% (36/73). Besides, the 5 multidrug resistant strains isolated in this study were all resistant to cadmium, indicating that in case of the involvement of Listeria monocytogenes with both cadmium and multidrug resistance in human disease, through food chains or environmental factors, the human health should be seriously threatened. Source


Cai X.-Q.,Chinese Academy of Agricultural Sciences | Cai X.-Q.,Technical Center | Yu H.-Q.,Technical Center | Li R.,Technical Center | And 6 more authors.
Scientific World Journal | Year: 2014

Clonorchis sinensis and Opisthorchis viverrini are both important fish-borne pathogens, causing serious public health problem in Asia. The present study developed an assay integrating real-time PCR and high resolution melting (HRM) analysis for the specific detection and rapid identification of C. sinensis and O. viverrini. Primers targeting COX1 gene were highly specific for these liver flukes, as evidenced by the negative amplification of closely related trematodes. Assays using genomic DNA extracted from the two flukes yielded specific amplification and their identity was confirmed by sequencing, having the accuracy of 100% in reference to conventional methods. The assay was proved to be highly sensitive with a detection limit below 1 pg of purified genomic DNA, 5 EPG, or 1 metacercaria of C. sinensis. Moreover, C. sinensis and O. viverrini were able to be differentiated by their HRM profiles. The method can reduce labor of microscopic examination and the contamination of agarose electrophoresis. Moreover, it can differentiate these two flukes which are difficult to be distinguished using other methods. The established method provides an alternative tool for rapid, simple, and duplex detection of C. sinensis and O. viverrini. © 2014 Xian-Quan Cai et al. Source

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