Analytical performance of an immunologic-based periodontal bacterial test for simultaneous detection and differentiation of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia.

The analytical performance of a membrane-based immunoassay for the simultaneous detection and differentiation of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia (including Prevotella nigrescens) was investigated. Positive reactions were observed for 71 of 71 reference strains and recent oral isolates of A. actinomycetemcomitans, P. gingivalis, and P. intermedia. No cross-reactivity was observed with 39 other common oral and environmental species. The specificity of the test was unaffected by the presence of potential oral interferents including whole blood, white blood cells, mucin, saliva, toothpastes, and oral rinses. A proficiency test by dental professionals using a standardized set of unknown simulated samples yielded a sensitivity of 97% (116/120) and a 100% specificity (240/ 240). An additional group including dental professionals and high school students was shown to be 99% proficient (1385/1397) in distinguishing proper from improper test function when processing control samples with normal test devices and devices with simulated error conditions. Comparisons to a culture standard for 104 subgingival plaque samples collected from 26 adult periodontitis patients yielded > 98% specificity for each of the test bacteria. In addition, the detection threshold for the test was determined to be equivalent to 10(4) cultivable test bacteria when compared to the culture standard. The data indicate that this membrane immunoassay is a valid and easy-to-use method for the detection of A. actinomycetemcomitans, P. gingivalis, and P. intermedia in subgingival plaque, at levels above the detection threshold of the test.