OBJECTIVES: Brucellosis is a major zoonotic disease that poses a significant public health threat worldwide. The classical bacteriological detection process used to identify Brucella spp. is difficult and time-consuming. This study aimed to develop a novel molecular assay for detecting brucellosis. METHODS: All complete sequences of chromosome 1 with 2.1-Mbp lengths were compared among all available Brucella sequences. A unique repeat sequence (URS) locus on chromosome 1 could differentiate Brucella abortus from Brucella melitensis. A primer set was designed to flank the unique locus. A total of 136 lymph nodes and blood samples were evaluated and classified by the URS-polymerase chain reaction (PCR) method in 2013–2014. RESULTS: Biochemical tests and bacteriophage typing as the golden standard indicated that all Brucella spp. isolates were B. melitensis biovar 1 and B. abortus biovar 3. The PCR results were the same as the bacteriological method for detecting Brucella spp. The sensitivity and specificity of the URS-PCR method make it suitable for detecting B. abortus and B. melitensis. CONCLUSION: Quick detection of B. abortus and B. melitensis can provide the most effective strategies for control of these bacteria. The advantage of this method over other presented methods is that both B. abortus and B. melitensis are detectable in a single test tube. Furthermore, this method covered 100% of all B. melitensis and B. abortus biotypes. The development of this URS-PCR method is the first step toward the development of a novel kit for the molecular identification of B. abortus and B. melitensis.
Bacteria ; Bacteriophage Typing ; Brucella abortus* ; Brucella melitensis* ; Brucella* ; Brucellosis ; Chromosomes, Human, Pair 1 ; Lymph Nodes ; Methods ; Polymerase Chain Reaction* ; Public Health ; Sensitivity and Specificity ; Zoonoses

Objective: To determine epidemiological, molecular characterization, and potential risk factors of human brucellosis. Methods: This descriptive study was carried out in the clinical setting in Iran between 2017 and 2018. A total of 297 participants enrolled in the study. The sample size was calculated based on the occurrence rate of brucellosis in different areas. Patients were assessed using serological tests and conventional culture methods. Phage and multiplex PCR methods typed all of Brucella isolates. Potential risk factors of disease were determined. Results: A total of 141 of 297 (47.5%) Brucella strains were isolated and all of them were detected as Brucella melitensis biovar 1. Based on serologic titers, high culture positivity was recorded at 1/640 titer (P< 0.006). The risk factors for brucellosis were patients older than 40 years (OR=2.23, 95%CI: 1.4-3.55, P=0.001), animal keeper (OR=7, 95%CI: 1.51-32.41, P=0.005), housewife (OR=8.76, 95%CI: 1.85-41.37, P=0.002), farmer (OR=6.42, 95%CI: 1.21-33.97, P=0.019), and contact with animal (OR=1.31, 95%CI: 0.60-2.85, P=0.005). Conclusions: To the best of our knowledge, this is the first comprehensive report from Iran presenting the detection of Brucella species by the multiplex PCR. Brucella melitensis biovar 1 is still the dominant causative agent in Iran. The consumption of unpasteurized dairy products, living in rural areas, and animal contact were risk factors of brucellosis.