Detection of Brucella Spp. in Raw Milk and Dairy Products of Traditional Domestic Dairy Sale Centers by Real-time PCR in Semnan

Introduction: Brucellosis, also known as Malta fever, is a significant zoonotic infectious disease in Iran, causing considerable public health and economic complications. Human infection is primarily acquired through the consumption of unpasteurized milk and dairy products. Conventional diagnostic approaches, such as culture and serology, are limited by low sensitivity, biosafety risks, and potential cross-reactivity. Molecular methods, particularly real-time polymerase chain reaction (real-time PCR), offer greater sensitivity and specificity. This cross-sectional study, investigated the presence of Brucella spp. in raw milk and traditional dairy products (cream, cheese, and ice cream) collected from local markets in Semnan, Iran. Materials & Methods: A total of ۹۵ samples were analyzed using real-time PCR with SYBR Green dye, targeting the bcsp۳۱ gene for genus-level detection and species-specific primers for Brucella abortus and Brucella melitensis. Additionally, the limit of detection (LOD) was evaluated using the serial dilution of Brucella standard strain. Results: The results revealed that among the samples tested, four samples were positive for Brucella spp. Specifically, three samples were confirmed as B. abortus, and one sample was identified as B. melitensis. Following propagation, DNA fragments of ۴۹۸ bp and ۷۳۱ bp, corresponding to B. abortus and B. melitensis, respectively, were successfully detected in the infected samples. Moreover, no significant overall difference in Brucella prevalence was found across products and bacterial load analysis revealed higher median colony-forming units (CFU) in cheese compared to milk and ice cream. Conclusion: These findings highlight the presence of Brucella contamination in dairy products sold through informal channels, emphasizing the need for improved monitoring, strict control strategies, and consumer education to reduce disease transmission.

کلیدواژه ها:

Brucella abortus ، Brucella melitensis ، Real-time polymerase chain reaction (realtime PCR ، traditional dairy products