Molecular Detection and Virulence Factor Profiling of Brucella 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, ۱۰۰ blood samples from patients suspected of brucellosis hospitalized at Sina Hospital, Hamadan, and ۱۰۰ animal samples from various livestock in this province were collected from November ۲۰۲۱ to October ۲۰۲۲. 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, ۶۱ Brucella isolates were collected, comprising ۳۶ from humans (۶ B. abortus and ۳۰ B. melitensis) and ۲۵ from animals (۵ B. abortus and ۲۰ B. melitensis). Approximately ۸۳.۳۳% of the isolates were B. melitensis, and ۱۶.۶% were B. abortus. The prevalence of virulence genes was ۸۶.۷۸% (znuA and bvfA), ۸۸.۵۲% (omp۲۵), ۸۱.۹۶% (omp۳۱), and ۱۰۰% (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.