Pi30 DNA probe may be useful for the identification of Prevotella intermedia at the species or strain level.

Recently, we introduced a new method for the rapid screening of bacterial species- or subspecies-specific DNA probes, named the "inverted dot blot hybridization screening method." This method has subsequently been then applied to develop species- or strain-specific DNA probes for Prevotella intermedia and Prevotella nigrescens. In a previous study, the inverted dot blot hybridization data showed that a probe, Pi30, was specific for P intermedia. In this study, the DNA probe Pi30 was evaluated by Southern blot analysis to determine if it could distinguish P intermedia from R nigrescens. The data showed that the probe WO reacted with the genomic DNAs from the reference strains and clinical isolates of both R intermedia and P nigrescens, but the size of the signal bands was different. In addition, the probe Pi30 reacted with a 1.4 kbp fragment from the genomic DNAs digested with PstI of the R intermedia strains but not with any fragments of P nigrescens strains. The result indicates that the probe Pi30 could be useful for the identification of P intermedia by restriction fragment length polymorphism (RFLP) at the species or strain level.