Molecular epidemiology of Brucella melitensis strains causing outbreaks in Croatia and Bosnia and Herzegovina

Abstract

The most recent data on the incidence of brucellosis in Southeast Europe prove the persistence of this zoonosis in the area, regardless of constant efforts at controlling it as one of the most dangerous zoonoses. Forty-three Brucella melitensis strains were collected from cattle, sheep, goats and humans from Croatia as well as Bosnia and Herzegovina between 2009 and 2015. The strains were identified and genotyped in order to determine their epidemiological background. Standard biotyping methods and Bruce-ladder were used to identify the strains. Genotyping was done using multilocus variable number tandem repeats analysis (MLVA) on 16 and multilocus sequence typing analysis (MLST) on nine loci. Results were compared to each other and to internationally available data. Twenty- five novel genotypes and two sequence types were identified. All tested strains, apart from vaccine and reference strains, showed very close phylogenetic and geographic relationships. The genotyping results indicate the endemicity of brucellosis in this region. MLST showed no variation, confirming the stability of housekeeping genes. The results confirm already established routes of disease spread in this area, showing that a more detailed and vigorous control of this zoonosis is necessary.