A novel real-time PCR assay for specific detection of Brucella melitensis

BACKGROUND: Brucellosis is a zoonosis that occurs worldwide. The disease has been completely eradicated in livestock in Sweden in 1994, and all cases of confirmed human brucellosis are imported into Sweden from other countries. However, due to an increase in the number of refugees and asylum seekers from the middle-east to Sweden, there is a need to improve the current diagnostic methodology for Brucella melitensis. Whilst culture of Brucella species can be used as a diagnostic tool, real-time PCR approaches provide a much faster result. The aim of this study was to set up a species-specific real-time PCR for the detection of all biovars of Brucella melitensis, which could be used routinely in diagnostic laboratories. METHODS: A Brucella melitensis real-time PCR assay was designed using all available genomes in the public database of Brucella (N = 96) including all complete genomes of Brucella melitensis (N = 17). The assay was validated with a collection of 37 Brucella species reference strains, 120 Brucella melitensis human clinical isolates, and 45 clinically relevant non-Brucella melitensis strains. RESULTS: In this study we developed a single real-time PCR for the specific detection of all biovars of Brucella melitensis. CONCLUSIONS: This new real-time PCR method shows a high specificity (100%) and a high sensitivity (1.25 GE/μl) and has been implemented in the laboratories of four governmental authorities across Sweden.