A Cross-reactivity Study of Whole Genomic DNA Probes for Haemophilus actinomycetemcomitans, Bacteroides intermedius, and Bacteroides gingivalis

In this study, we evaluated the sensitivity and specificity of whole genomic DNA probes for the periodontal pathogens Haemophilus actinomycetemcomitans, Bacteroides intermedius, and Bacteroides gingivalis. By means of these probes, DNA hybridizations were performed against other organisms found in the oral cavity and organisms previously determined to be genetically similar. All three probes were sensitive to 103 cells for their respective organism. The H. actinomycetemcomitans probe cross-reacted with several haemophilus strains, Wolinella, and Campylobacter, indicating that H. actinomycetemcomitans-specific sequences would have to be identified and cloned for accurate detection of this organism in heterogeneous patient samples. Only very low levels of cross-reactivity were observed between the B. intermedius probe and representative black-pigmented Bacteroides. This low level of cross-reactivity did not interfere with the accurate identification of B. intermedius in sample evaluations. The B. gingivalis probe showed no cross-reactivity. Whole genomic probes will be used for the detection of B. intermedius and B. gingivalis in patient samples.