PCR as a diagnostic tool for brucellosis.

Numerous PCR-based assays have been developed for the identification of Brucella to improve diagnostic capabilities. Collectively, the repertoire of assays addresses several aspects of the diagnostic process. For some purposes, the simple identification of Brucella is adequate (e.g. diagnosis of human brucellosis or contamination of food products). In these cases, a genus-specific PCR assay is sufficient. Genus-specific assays tend to be simple, robust, and somewhat permissive of environmental influences. The main genetic targets utilized for these applications are the Brucella BCSP31 gene and the 16S-23S rRNA operon. Other instances require identification of the Brucella species involved. For example, most government-sponsored brucellosis eradication programs include regulations that stipulate a species-specific response. For epidemiological trace back, strain-specific identification is helpful. Typically, differential PCR-based assays tend to be more complex and consequently more difficult to perform. Several strategies have been explored to differentiate among Brucella species and strains, including locus specific multiplexing (e.g. AMOS-PCR based on IS711), PCR-RFLP (e.g. the omp2 locus), arbitrary-primed PCR, and ERIC-PCR to name a few. This paper reviews some of the major advancements in molecular diagnostics for Brucella including the development of procedures designed for the direct analysis of a variety of clinical samples. While the progress to date is impressive, there is still room for improvement.