Molecular Detection and Virulence Factor Profiling of <i>Brucella</i> Species Isolated from Humans and Livestock in Hamadan Province, West of Iran

Background: Brucellosis is a prevalent zoonotic disease that impacts both humans and livestock. While most developed countries have effectively controlled this disease, it has not yet been eradicated in Iran, particularly in Hamadan Province. Accordingly, this research isolated and molecularly characterized Brucella species from humans and livestock in this province and then evaluated the presence of virulence genes in the isolates via multiplex PCR analysis. Methods: Overall, 100 blood samples from patients suspected of brucellosis hospitalized at Sina Hospital, Hamadan, and 100 animal samples from various livestock in this province were collected from November 2021 to October 2022. The samples were subsequently cultured on specialized media, and the resulting isolates underwent both biochemical and molecular analyses. Then, a multiplex PCR assay was developed to concurrently detect the genus Brucella and distinguish between the species B. abortus and B. melitensis using primers specific to the genus and each species. The prevalence of virulence factor-associated genes in the identified species was examined by multiplex PCR. SPSS was used for data analysis, with the chi-square test employed to explore the associations between variables. Results: In general, 61 Brucella isolates were collected, comprising 36 from humans (6 B. abortus and 30 B. melitensis) and 25 from animals (5 B. abortus and 20 B. melitensis). Approximately 83.33% of the isolates were B. melitensis, and 16.6% were B. abortus. The prevalence of virulence genes was 86.78% (znuA and bvfA), 88.52% (omp25), 81.96% (omp31), and 100% (mviN). Conclusion: The findings suggest that brucellosis remains a significant challenge in Hamadan Province, requiring comprehensive and effective control measures. Furthermore, the high prevalence of virulence genes in isolates from this region significantly increases the pathogenic potential of the bacteria.