FIG. 1.
Sensitivity of PCR assay for detection of our fimA types of P. gingivalis. The sensitivity of the PCR assay was studied with titrated cultures of P. gingivalis of four fimA types (types I to IV; 109 cells of strains 381, HW24D-1, OMZ314, and HG564, respectively, per ml). The detection limit was determined for the simultaneous PCR by the use of known numbers of bacterial cells diluted in sterile distilled water. The following numbers of cells were added: 5 × 105 (lane 1), 5 × 104 (lane 2), 5 × 103 (lane 3), 5 × 102 (lane 4), 5 × 10 (lane 5), and 5 (lane 6). Lane 7, a negative control from the PCR without any bacterial cells; lane 8, a PCR product obtained with P. gingivalis species-specific 16S rRNA primers (5 × 103 cells); lane M, molecular size marker (a 100-bp DNA ladder).