Molecular typing of Brucella species in human brucellosis cases from Eastern Türkiye

Abstract

Brucellosis remains a critical zoonotic infection with profound implications for public health across diverse regions, including the Middle East, Asia, the Arabian Peninsula, the Mediterranean, Africa, and South and Central American countries. This global threat necessitates ongoing investigation and surveillance. Accordingly, this study aimed to elucidate the presence and characteristics of Brucella spp. isolated from patients in a province of eastern Türkiye. A combination of conventional and molecular techniques was employed to achieve comprehensive species and biovar determination. A total of 189 human Brucella spp. strains isolated from blood cultures at Bitlis State Hospital between 2010 and 2020 were included in the study. Identification tests for the isolates comprised assessing serum requirement for growth, oxidase and urease production, as well as lysis testing with Tbilisi phage and R/C phage. Additional conventional biotyping tests involved evaluating hydrogen sulfide (H2S) production, carbon dioxide (CO2) requirement for growth, and growth in media containing thionin, basic fuchsin, and safranin. Furthermore, agglutination with Brucella A and M type monospecific antisera was performed. The isolates also underwent multiplex PCR, specifically the Bruce–Ladder PCR method, for biotyping. The results demonstrated the predominance of Brucella melitensis strains in human brucellosis cases, as identified by both conventional and molecular methods. Specifically, 185 isolates were classified as B. melitensis biovar 3, with the remaining 5 isolates classified as B. melitensis biovar 1. In conclusion, this distribution underscores the significant role of B. melitensis in the epidemiology of human brucellosis in the region. The current study highlights the efficacy of both conventional and molecular methods in Brucella spp. identification, with particular emphasis on the Bruce–Ladder PCR method’s superiority in terms of rapidity and compatibility with traditional techniques. Continued research and surveillance efforts are imperative to deepen our understanding of the epidemiology and dynamics of this zoonotic disease.

Keywords

• Brucellosis
• Brucella melitensis
• multiplex polymerase chain reaction