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This investigation examined the ability of cells of Bacteroides melaninogenicussubsp. asaccharolyticus381 to adhere to surfaces that might be important for its initial colonization of the mouth and its subsequent colonization in periodontal pockets. Of 48 asaccharolytic strains of B. melaninogenicus, 47 agglutinated human erythrocytes, whereas none of 20 fermentative strains, which included reference cultures of the subspecies intermediusand melaninogenicus, were active. Electron microscopy indicated that both asaccharolytic and fermentative strains possessed pili; hence, the presence of pili did not correlate with the hemagglutinating activities of B. melaninogenicusstrains. Both asaccharolytic and fermentative B. melaninogenicusstrains suspended in phosphate-buffered saline adhered in high numbers to buccal epithelial cells and to the surfaces of several gram-positive bacteria tested, including Actinomyces viscosus, A. naeslundii, A. israelii, Streptococcus sanguis, and S. mitis. B. melaninogenicussubsp. asaccharolyticus381 also attached, but in comparatively low numbers, to untreated and to saliva-treated hydroxyapatite. Addition of clarified whole saliva to suspensions of strain 381 almost completely eliminated adherence to buccal epithelial cells and to hydroxyapatite surfaces, but saliva had no detectable effect on attachment to gram-positive plaque bacteria. Both fermentative and nonfermentative strains of B. melaninogenicusalso attached in high numbers to crevicular epithelial cells derived from human periodontal pockets, but normal human serum strongly inhibited attachment. Serum also inhibited attachment of strain 381 to saliva- and serum-treated hydroxyapatite, but it had little effect upon attachment to gram-positive bacteria. These observations suggested that salivary and serum components would strongly inhibit the attachment of B. melaninogenicuscells to several oral surfaces, but not to the surfaces of certain gram-positive bacteria commonly present in human dental plaque. This was confirmed by an in vivo experiment in which streptomycin-labeled cells of B. melaninogenicus381-R were introduced into the mouths of two volunteers. After 10 min, several hundred-fold higher numbers of the organism were recovered from preformed bacterial plaque present on teeth than from clean tooth surfaces or from the buccal mucosa and tongue dorsum. High numbers of B. melaninogenicuscells were also recovered from preformed plaque after 150 min, but virtually no cells of the organism were recovered from the other surfaces studied. These data suggest that the presence of dental plaque containing Actinomycesand other gram-positive bacteria may be essential for the attachment and colonization of B. melaninogenicuscells after their initial introduction into the mouth. Similarly, the presence of subgingival plaque containing gram-positive bacteria may be necessary for its secondary colonization in periodontal pockets.

Virulent M protein-containing strains of Streptococcus pyogeneswere found to adhere well to human pharyngeal cells in vitro. In contrast, an avirulent M - strain and an enteropathogenic Escherichia colistrain adhered feebly. When various rat tissues were exposed to mixtures of a virulent S. pyogenesstrain and an enteropathogenic E. colistrain, the relative proportions of the two pathogenic strains recovered from mucosal surfaces differed among the sites studied. S. pyogenescells were found to adhere in higher proportions than enteropathogenic E. colicells to the mucosal surfaces of rat tongues, whereas on surfaces of the urinary bladder, their affinities were reversed. The data indicate that bacterial adherence is influenced by the specificity of both the bacterial and epithelial surfaces, and they suggest that adherence may influence the tissue tropisms of pathogens. Early stationary-phase cells of S. pyogenesattached better to epithelial cells than did bacteria in other growth phases. The adherence of S. pyogenescells was impaired by pretreatment with trypsin, wheat germ lipase, Tween 80, Triton X-100, sodium lauryl sulfate, heat at 56 C, anti-group A antiserum, the presence of phospholipids, and preincubation of the epithelial cells with Streptococcus salivariuscell walls. Altering the pH or treatment with ethylenediaminetetraacetic acid had no effect on the ability of S. pyogenescells to adhere.

Loesche, WalterJ. (Forsyth Dental Center and Harvard School of Dental Medicine, Boston, Mass.), Ronald J. Gibbons, and Sigmund S. Socransky. Biochemical characteristics of Vibrio sputorumand relationship to Vibrio bubulusand Vibrio fetus. J. Bacteriol. 89:1109–1116. 1965.—Twenty-seven strains of Vibrio sputorumwere isolated from human gingival debris. All strains reduced nitrate beyond nitrite, and all produced H2S. None produced catalase, indole, or acetylmethylcarbinol. Carbohydrates were not fermented, and acid end products or volatile neutral products could not be detected. Motility was observed infrequently, although 14-hr cultures usually had a few cells which displayed darting motility. Shadowed electron microscopic preparations demonstrated that most cells in a given culture were nonflagellated, although some cells with a single terminal or subterminal flagellum were always observed. V. sputorumwas demonstrated not to be a strict anaerobe as previously described, but rather a microaerophile. Addition of nitrate to culture media markedly enhanced growth. V. sputorumwas found to be closely related to the animal microaerophilic vibrios, V. bubulusand V. fetus. V. sputorumdiffered from V. fetusby being capable of anaerobic growth, producing H2S, and failing to produce catalase or to grow in 10% O2. Antigens of V. sputorumcross-reacted in low titer with antisera to V. fetusserotypes I, II, III, and V. V. sputorumdiffered from V. bubulusby being inhibited by 3.5% NaCl and by qualitative differences in growth in the presence of 1% glycine and 10% O2. These differences do not appear sufficient to recognize two distinct species, and it is proposed that both species be recognized as V. sputorum, which has priority. Strains unable to grow in 3.5% NaCl would be considered V. sputorumvar. sputorum, whereas strains capable of growth in 3.5% NaCl would be V. sputorumvar. bubulum.

Lactobacilli were found in saliva, on teeth, and on the dorsum of the tongue, the vestibular mucosa, and the hard palate in humans. Their proportions in saliva, expressed as percentage of the anaerobically cultivable flora, were 10- to 100-fold higher than those on the tooth surface, but were comparable to those on the epithelial surfaces. The adherence of Lactobacillus caseiand L. fermentito oral surfaces was compared with that of streptomycin-labeled Streptococcus sanguisand S. salivariusby using in vitro-cultivated cells. The affinity of both Lactobacillusspecies for the tooth surface was very low compared with that of S. sanguisbut was somewhat higher than that of S. salivarius.The lactobacilli and both Streptococcusspecies adhered to a similar extent to the dorsum of the tongue, whereas the affinity of the lactobacilli and S. salivariusfor the vestibular mucosa was about one-half of that of S. sanguis.The results suggest that the affinity of lactobacilli for oral surfaces significantly influences their proportional distribution in the mouth. The relatively low affinity of lactobacilli for the tooth surface suggests that their recognized association with carious lesions and mechanical appliances under certain conditions may be due primarily to mechanical retention rather than unique growth conditions.