Molecular epidemiological characteristics of human derived Brucella isolated in Hohhot

Objective To get knowledge of the molecular epidemiological characteristics of human derived Brucella isolated in Hohhot, and to provide experimental basis in guiding prevention and treatment of Brucella infection. Methods Twenty-seven Brucella isolates derived from patients in Affiliated Hospital of Inner Mongolian Medical University from 2013 to 2015 were identified by routine bacteriological methods and molecular methods. Multiple-locus variable number tandem repeats analysis (MLVA-16) was used to detect molecular typing and do cluster analysis. Sixteen virulent genes were detected and analyzed by polymerase chain reaction (PCR). Results Twenty-seven Brucella isolates were identified as Brucella melitensis (B. melitensis) by routine bacteriological methods and PCR. Out of them, six isolates were B. melitensis biovar 1, and twenty-one isolates were B. melitensis biovar 3. MLVA-16 analysis showed that seven genotypes were obtained from nine Brucella isolates, which showed significant difference in variable number of tandem repeats, which suggested that they originated from sporadic outbreak. Moreover, two isolates were clustered into the same clade, which suggested they were epidemiologically correlated and may be derived from the same origin. Sixteen virulent genes were detected in all of the twenty-seven isolates. Conclusions Brucella isolates from patients in Hohhot are mainly B. melitensis biovar 3 and B. melitensis biovar 1, and the distribution profile of multiple virulence genes is similar. Some isolates have showed epidemic correlation, and the epidemic mechanism should be further explored. Key words: Brucella; Identification; Virulent genes; Molecular typing