Investigating the Rate of Contamination of Milk and Traditional Dairy Products with Brucella Bacteria by PCR Method, Mamasani District, Fars Province, South of Iran

Abstract

Background & aim: The health of milk and its products is of great importance due to its high nutritional value. This nutrient medium is contaminated by microbial agents. Brucellosis is considered one of the most important zoonotic diseases and is endemic in the Middle East countries and has been reported in human and livestock populations in different parts of Iran. Brucellosis is an infectious bacterial disease caused by a microorganism of the genus Brucella and transmitted through unpasteurized milk and dairy products. The aim of the present study was to investigate the prevalence of contamination of milk and traditional dairy products with Brucella bacteria by PCR method, Mamasani district, Fars province, south of Iran. Methods: In the present cross-sectional descriptive study conducted in 2021, 200 samples of traditional dairy products including 50 samples of raw milk, 50 samples of yogurt, 50 samples of cheese and 50 samples of butter from livestock farms in rural areas and inner-city shops of Mamasani district were collected and transferred to the microbiology laboratory. In order to identify the possible type of Brucella bacteria in the samples, the culture medium containing the supplement was used to prevent the growth of other pathogens. DNA of samples was extracted by DNp kit. In order to optimize the PCR test, the DNA sample was extracted from the standard strain of bacteria by boiling method and (cat: DN 811530) DNG. In each reaction, template DNA, primers (Bru and Low Bru Up), magnesium chloride, dNT and Taq DNA polymerase enzyme were used according to the instructions. The second step reaction was optimized with the same values. In the second step, instead of template DNA, the product of the first round was used. Second stage primers include Bru Up, Bru In primers. The collected data were analyzed using SPSS software and chi-square statistical test. Results: The results of the present study indicated that 1.86%, 2.8%, 0.3% and 0% of raw milk, cheese, yogurt and butter samples were infected with Brucella melitensis bacteria, respectively. The optimized PCR test had a very high specificity, as a result it did not react with any of the studied DNAs except Brucella DNA. Conclusion: Although contact with animals and products infected with Brucella bacteria are known as the most important factors of brucellosis, but then again the climatic conditions and the type of animal farming and the eating behavior of the people in the way of using animal products as well as the pathogen species in each geographical area are the factors that determine the pattern of the disease. It displays the incidence of disease in different societies. The obtained results indicated that despite the measures taken to prevent Brucellosis disease, there was still a possibility of contamination of dairy products with Brucella bacteria.

Keywords

• brucellosis
• pcr
• fars
• iran