Immunomagnetic PCR and DNA probe for detection and identification of Porphyromonas gingivalis.

The aim of the study that we describe was to combine an immunomagnetic separation and a PCR followed by dot blot hybridization with a DNA probe for the detection and identification of Porphyromonas gingivalis. Immunomagnetic particles were coated with monoclonal antibody specific for P. gingivalis and were incubated with a suspension containing seven oral bacterial species spiked with various dilutions of P. gingivalis. Beads with their load of bound bacterial were boiled in water, and the target DNA in the supernatant was amplified with a primer pair to generate a 593-bp PCR fragment specific for P. gingivalis. Finally, the product of amplification was detected by dot blot hybridization with a digoxigenin-labeled 593-bp probe. The detection limit was determined to be 100 bacterial cells per ml. The immunomagnetic-PCR/DNA probe procedure described here should be useful for the rapid, specific, and sensitive detection and identification of P. gingivalis in clinical samples.