The hybridization products obtained by PCR using sequence-specific oligonucleotides (PCR-SSO) can be traced either by colorimetric-(streptavidin-biotin), X-ray-(digoxigenin-CSPD), or fluorescence-(FITC, PE) based detection systems. To achieve a faster, reliable, automated typing, microbead and fluorescence detection technology have been combined and introduced to this field (XMAP™ technology). For each locus, a maximum of 100 microspheres, which are recognizable by their specific color originating from two internal fluorescent dyes, are used. Each microsphere is coupled with a single probe that is capable of hybridizing with the biotin labeled complementary amplicon. Once hybridization occurs, it can be quantified via the fluorecence signal originating from fluorescently (Streptavidin-PE) labeled amplicons captured by the beads. Currently, there are two commercially available systems that differ in the scale of probes and the method of amplification or denaturation. One of these will be described in detail in this chapter.
