Species identification and molecular characterization of human Brucella strains isolated in Ningxia Hui Autonomous Region, 2019−2022

Objective To understand the species type and molecular characteristics of human Brucella isolates in Ningxia Hui Autonomous Region (Ningxia) from 2019 to 2022 and provide evidence for the precise prevention and control of human brucellosis.

Methods Brucella isolates were identified by AMOS polymerase chain reaction (AMOS-PCR), molecular typing of the isolates was performed by multilocus variable number of tandem repeat sequence analysis (MLVA), and the clustering analysis was conducted by using software BioNumerics 7.6.

Results A total of 72 Brucella isolates were identified by AMOS-PCR. The results showed that all the isolates were Brucella melitensis. After MLVA typing , the isolates belonged to 3 MLVA-8 types, 42, 45 and 63 in Panel1. The isolates all belonged to type 41 (4-20-8) in Panel2A and the isolates showed a high degree of variability in Panel2B. 72 isolates were classified into 51 MLVA-16 genotypes, including 12 common genotype and 39 unique genotypes. More Brucella types were found in Yuanzhou district, including three MLVA-8 types. The 72 Brucella strains in this study shared 18 identical MLVA-16 genotypes with the strains isolated in several provinces, indicating the cross-regional transmission in the country.

Conclusion Human brucellosis epidemic is extremely serious in Ningxia, and MLVA-16 have found the existence of multiple genotypes of Brucella in Ningxia, providing evidence for the precise prevention and control of human brucellosis and epidemiological tracing of human brucellosis cases.