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This study was undertaken to determine the frequency of Legionella infection in a dental clinic setting. Serum samples from 270 dental clinic personnel were evaluated using an enzyme-linked immunosorbent assay to detect Legionella-specific IgM and IgG antibodies. The pooled-species whole-cell-antigen preparation used in these assays was derived from six Legionella pneumophila strains and one strain each from Legionella bozemanii and Legionella micdadei. Significant levels of IgG and IgM antibodies were found in 20% and 16%, respectively, of the samples. This compares with 8% and 10%, respectively, for a randomly selected non-clinical group from the region (P less than 0.005). Samples from clinic personnel with significant IgG titers (greater than 1:128) were also evaluated for activity to each of the eight single-species antigens, with the following results: L. pneumophila, 45% (combined six strains); L. micdadei, 37%; and L. bozemanii, 18%. Comparing individuals' "years spent in the clinic environment" with the incidence of significant antibody levels strongly suggests that the risk of Legionella infection increases proportionately with increased clinic exposure time (P less than 0.05). Analysis of these data implies that Legionella may be present in the dental clinic environment, thus creating an increased risk for clinical personnel or patients.

Colony phenotype and genetic similarity were assessed within and between groups of commensal and pathogenic strains of Candida albicans collected from the oral cavities of individuals in a single geographical locale. Thirty-eight percent of pathogenic isolates contained predominant or minor variant colony morphologies (other than smooth) when samples from the sites of infection were cultured on plates, while 16% of commensal isolates contained minor variant colony morphologies when samples from the sites of carriage were cultured. The genetic similarities of isolates within and between groups were assessed by DNA fingerprinting by using Southern blot hybridization with the fingerprinting probe Ca3 and analysis with the computerassisted, automated Dendron system. Both the commensal and the pathogenic groups contained a major cluster of genetically similar C. albicans isolates representing 31 and 33% of the strains in the respective groups. When a combined dendrogram of both commensal and pathogenic isolates was generated, the major clusters of genetically similar isolates in each group mixed into one large cluster.

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