DNA-DNA Checkerboard Hybridization to Identify Bacteria in Human Plaque Samples

Previous research has shown that using DNA probes to identify the presence of specific bacteria in human plaque samples is superior to the commonly used anaerobic cultural procedures. Some periodontal pathogens are either uncultivable or very difficult to grow, such as Prevotella intermedia, P. nigrescens, and Eubacterium brachy. Digoxygenin probes were prepared for 15 oral bacteria. These probes were used with a checkerboard DNA-DNA hybridization scheme to analyze whether human plaque samples contained any of the 15 bacterial species. Our results have shown that this method is successful in identifying bacterial DNA present in the subgingival patient plaque samples. Probe cross-reactivity tests were also performed and have shown that there was very little cross-reactivity between the 15 bacterial species used. This method can be used for rapid and specific identification (compared to current anaerobic culturing methods) of bacterial species in human plaque samples, thus potentially facilitating treatment for pathogens implicated in periodontal diseases