| Campylobacter jejuni is one of the major bacterium that causes diarrhea, besides, it can cause food poisoning with Arthritis hepatitis guillain-barre syndrome disorders such as immune injury. It needs rigid living condition but easy to cause human and animal diseases. Because there is less systematic data to assess the contamination status about C.jejuni in retail food in China, our group decide to carry out the national C.jejuni contamination survey to know the pollution pattern at macro level and explore the characteristics of strains from the micro prospective, to provide the theory basis for reducing the food safety problems caused by C. jejuni.1. This paper introduced the C.jejuni in retail food pollution investigation and characteristics from July 2013 to June 2014 in major cities of China.1798 samples about 7 kinds of foods were studied,59 samples were positive, and the average positive was 3.3% (59/1798). The positive samples were mainly poultry meat, and we found the pollution rate of south China was higher than north China. According to detection of hipO and 16S rRNA genes combined with biochemical identification,34 isolates were collected.2. C.jejuni is difficult to culture and preserve to long-time, so we explored the preservation condition. It was found that the low temperature was essential and the 0.025%FBP brucella broth with 20% glycerin was excellent survive liquid after 18 months study, besides,80% defibrinated sheep’s blood with 20% glycerin also had the same effect with the former method.3. The research were studied the characteristic of these isolates about antibiotics resistance and drug resistance gene mutation, flaA PCR-RFLP genotyping and 11 kinds of virulence-related genes. It was found that 20 isolates had resistance to more than 5-8 kinds of antibiotics, and 2 isolates resistance to 9 antibiotics. Besides, resistance to quinolone reached 88.5% in isolates. MAMA-PCR was used to detected the gyrA gene mutation in C257T, and all of the strains that had resistance to quinolone had mutation in this point, which caused threonine became isoleucine. As for the results of the PCR-RFLP,21 types of 34 isolates were divided into six clusters at a relative similarly coefficient of 0.81, which showed the perfect discrimination by this genotyping method. The 11 kinds of virulence-related genes associated with adhesion, fixed, and attack were detected by PCR in isolates, it was found that more than 60% isolates that had the genes associated with genes associated with adhesion and fixed,but less 10% isolates had the genes including cjaB, pldA and imaA with attack.4. The biofilm of C.jejuni is difficult to form alone, but when it co-cultured with Pseudomonas aeruginosa and Escherichia coli, there was plenty biofilm can be formed. In the study, by comparing the amount of biofilm in the aerobic condition and microaerobic condition, we found the aerobic condition more benefit to form biofilm than microaerobic condition. In order to inhibit biofilm formation, three concentration nanoparticles ZnO were added to media before culture, and it was found that 0.5mg/ml nanoparticles ZnO could inhibit the biofilm formation to seen by scanning electron microscope and laser scanning confocal microscope.This study conducted the C.jejuni contamination survey and characteristics of C.jejuni research, which provided the data for evaluating the risks of contamination and pathogenic in retail food in China. The biofilm research was given the new way to control the contamination of C.jejuni in the food industry. |
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