Molecular Typing of Brucella melitensis Isolated from Patients and Animals by Pulsed Field Gel Electrophoresis from Iran

Background: The Brucellosis is recognized as a significant public health problem, with major economic and financial burdens in countries where the disease remains endemic. The disease is one of the most important worldwide zoonosis affecting livestock and humans. The aim of the present study was to genotypically characterize Brucella strains isolated from human and animal samples in two provinces of Iran.

Methods: Twenty seven Brucella strains isolated from patients and animals during April 2015 - December 2016. Thirteen human and fourteen animal strains were identified by biochemical tests and confirmed by amplification of fragment 1100bp omp2a gene using Polymerase Chain Reaction (PCR) method. Isolates were genotypically characterized by XbaI digestion and pulsed-field gel electrophoresis (PFGE) technique.

Results: In PFGE analysis totally, 7 common clones and 3 single clones were obtained. In genotyping, in two clones/clusters, human isolates were grouped with genotypes from animal isolates. Also PFGE results indicated 21 Brucella strains an overall similarity higher than 90%, and three clusters based on 100% similarity were revealed.

Conclusion: According to dendrogram clinical strains had a high degree of homology compared to animal strains. The information of this study indicating a close genetic relatedness or common origin of the isolates in the two geographical region of Iran and it implies that B. melitensis cross-infected between human and livestock.