Dissertation > Industrial Technology > Light industry,handicrafts > Food Industry > General issues > Food standards and testing > Microbiological testing of food

Investigation and Analysis of Pathogenic Microorganisms in Cold Dishes of Shandong Province

Author DingBo
Tutor YangChunYu
School Shandong University
Keywords Cold dishes Pathogenic microorganisms Food safety Activesurveillance Resistance
CLC TS207.4
Type Master's thesis
Year 2013
Downloads 47
Quotes 0
Download Dissertation

Objectives:Food safety problems related to the national health, economic construction and social stability, it is the focus of attention of all sectors of society. At present, diseases caused by pathogenic microorganisms that have become one of the major food safety problems in China. The main topic for study of pathogenic microorganisms in cold dishes, aquatic food products, process of manufacture and so on. Mainly include Staphylococcus aureus, Listeria monocytogenes, salmonella, Shiga toxin-producing Escherichia coli(STEC), Vibrio Parahemolyticus, Vibrio cholera and Vibrio vulnificus. Comprehensive investigation of these pathogenic microorganisms in cold dishes. Continuous monitoring of food contamination by pathogenic microorganisms. Thorough analysisthe riskiest foods in food service establishments to master the variation catering services link the hazard factor. To provide a scientific, effective supervision on the basis of the food and Drug Administration.Methods:Related pathogens of staphylococcus aureus, Listeria monocytogenes and Hemorrhagic Escherichia coli(EHEC, O157:H7). with reference to national inspection standards(GB4789) on the basis of appropriate improvements. Mainly to make individual adjustments to few steps. We used some better effected medium, such as BPRPF made by BioMerieux for Staphylococcus aureus and other medium made by The French CHROMagar company. Detection of Staphylococcus aureus enterotoxin main advantage of VIDAS30made by BioMerieux for Staphylococcus aureus enterotxin SEA, SEB, SEC, SED and SEE testing.Related pathogens of salmonella, Shiga toxin-producing Escherichia coli(STEC) with reference to Food safety inspection agency the United States Department of agriculture standards (FSIS, USDA). Using double PCR detection of Stxl and Stx2gene of STEC. Related pathogens Vibrio Parahemolyticus, Vibrio cholera and Vibrio vulnificus with reference to life technology company of America. By this TaqMan probe technology, we can Simultaneous determination of the three kinds of pathogenic bacteria. Using the VITEK compat system to Identification of all pathogenic bacteria which were detected from the cold dishes.Results:In this paper, about4kinds of cold pathogen was monitored. Including fruits, vegetables, poultry, meat, eggs, fish, shrimp and other raw materials, all the samples are about morn than1840. A total of302samples were contaminated by the pathogenic microorganisms, there are5batches of samples were contaminated by two kinds of pathogenic bacteria. The total detection rate (total sample) was16.4%. In the1840samples,the total number of the pathogenic microorganisms is about306.Among all the pathogenic microorganisms,117of them are Staphylococcus aureus,48of them are salmonella,111of them are Listeria monocytogenes,30of them are Vibrio Parahemolyticus. Escherichia coli, Shiga toxin-producing Escherichia coli, Vibrio cholera and Vibrio vulnificus are not detected. The positive rate of452vegetable salad samples is14.2%. the positive rate of433meat samples is16.2%, the positive rate of446seafood is17.5%, the positive rate of509mixed food is17.7%.There was no significant difference in these four kinds of cold dishes (X2=2.7, P>0.005). The positive rate of the first Sampling region is15.4%in the423samples; the second region is20.1%in the393samples;the third region is13.6%in the357samples; the fourth region is16.1%in the365samples. There was no significant difference in these four regions from the chi-square statistics(X2=7.8, P>0.005).42strains of enterotoxin was detected in117Staphylococcus aureus, and enterotox in production was observed in35.9%. In addition to the2strains could not be determined, the serotypes of48Salmonella strains which had been identified in cold dishes were belonged to7groups:S. Mercury16strains, S Anatum12strains, S Choleraesuis subsp7strains, S Enteritidis5strains, S Shubra2strains, S Irumu2strains, S Typhimurium1strains, S Gallinarum1strains. There were53S. aureus resistance to antimicrobials, multidrug resistance were common, the resistance rate was45.3%. Co-resistance to pencillin-G and erythromycin acid in a high level. There were12L. monocytogenes resistance to antimicrobials, the resistance rate was10.8%. A few of them resistant to at least five antimicrobials. Co-resistance of30V. Parahemolyticus to amikacin and ampicillin acid in a high level.5of them were resistant to cephalosporin antibiotics,3of them were resistant to lomefloxacin. A mony48Salmonella, the drug-sensitivities of them strains to amikacin, amoxicillin, ampicillin, ciprofloxacin, tetracycline and sulfonamide33.3%,45.8%,52.1%and31.2%. Thirty eight of them were resistant to at least two antimicrobials, Sixteen were resistant to at least five antimicrobials. Some of the serotypes and genetypes of foodborne Salmonella resistant to amikacin, amoxicillin, ampicillin, ciprofloxacin, tetracycline and sulfonamide began to increase every year in Shandong Province.Conclusion:According to active surveillance on cold dishes pathogenic microorganisms in Shandong Province, the overall situation is not optimistic. Regulators should be combined with the actual situation, in order to improve foodborne disease surveillance network in Shandong province and the regulatory system. Also,It is necessary to strengthen the basic laboratory detection ability and put the control of food borne pathogens as a long-term focus. According to active surveillance, the pollution by S.aureus was the highest, secondly was L. monocytogenes. Supervision department should focus on the prevention of these two pathogenic bacteria and the positive rate of pollution in each enterprise products for food safety evaluation of enterprise.The detection of Vibrio parahaemolyticus and Salmonella serotypes distribution shows regional certain rules, so it should be based on the specific circumstances to focus on monitoring of major hazards.Active surveillance results shows that the contamination of drug-resistant pathogenic bacteria was relatively serious, and had a rise trend. Multidrug resistance was common.Except o increase the inspection and punishment for terminal product, the most thine is to focus on the source of the problem. Strengthening the antibiotic production, sales management, giving farmers professional guidance and veterinary drug classification, Perfecting the supervision system and so on,from the source to curb the abuse of antibiotics. Only in this way can we ensure that people get their high quality food.

Related Dissertations
More Dissertations