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Background: The co-aggregation of oral bacteria leads to their clearance from the oral cavity. Poor oral hygiene and high saliva viscosity are common amongst the elderly; thus, they frequently suffer from pneumonia caused by the aspiration of oral microorganisms., Objectives: To examine the direct effect of saliva viscosity on the co-aggregation of oral streptococci with actinomyces., Materials and Methods: Fifteen oral streptococcal and a single actinomyces strain were used. Co-aggregation was assessed by a visual assay in phosphate buffer and a spectrophotometric assay in the same buffer containing 0-60% glycerol or whole saliva., Results: Nine oral streptococci co-aggregated with Actinomyces naeslundii ATCC12104 in the visual assay and were subsequently used for the spectrophotometric analysis. All tested strains displayed a decrease in co-aggregation with increasing amounts of glycerol in the buffer. The co-aggregation of Streptococcus oralis with A. naeslundii recovered to baseline level following the removal of glycerol. The per cent co-aggregation of S. oralis with A. naeslundii was significantly correlated with the viscosity in unstimulated and stimulated whole saliva samples (correlation coefficients: -0.52 and -0.48, respectively)., Conclusion: This study suggests that saliva viscosity affects the co-aggregation of oral streptococci with actinomyces and that bacterial co-aggregation decreases with increasing saliva viscosity., (© 2011 The Gerodontology Society and John Wiley & Sons A/S.)

Serological variations were examined among 12 type or reference strains and 91 oral isolates of vitamin B6-dependent Abiotrophia and Granulicatella spp. Rabbits were immunized with whole cells of 12 selected strains and 10 typing antisera were obtained, which were unreactive with the Lancefield group A to G antigen preparations. The reactivity of the antisera and autoclaved cell surface antigen extracts was tested by double diffusion in agar gel and a capillary precipitin test. These typing antisera categorized all Abiotrophia defectiva strains, all except one Granulicatella elegans strain, three-quarters of the Granulicatella adiacens, and half of the Granulicatella paraadiacens into 8 serotypes and 2 subserotypes. The Granulicatella balaenopterae type strain was unserotypable. All A. defectiva strains were serotype I, some of which were divided into subserotype I-1 and/or I-5. The G. adiacens strains generally belonged to serotype II or III, and the G. paraadiacens strains to serotype IV, V or VI. All G. adiacens or G. paraadiacens serotype II strains were also subserotype I-5. The G. elegans strains were serotype VII or VIII. These Abiotrophia and Granulicatella serotypes were undetectable among 33 strains of the other 11 species including the bacteriolytic enzyme-producing but vitamin B6-independent strains of Streptococcus, Enterococcus, Dolosigranulum and Aerococcus. The proposed serotyping system for Abiotrophia and Granulicatella spp. would be helpful in the identification and classification of these unique coccal isolates in ecological and epidemiological studies.

Various serotypes reported in three serotyping systems for the 'Streptococcus milleri' group, i.e., Ottens I-IV, Osano I-IV and serotypes a-k, were compared with each other in a capillary precipitation test and by the double immunodiffusion test. Only two of the 19 serotypes, f and Ottens-III, were identical, and the other 17 serotypes were independent. Thus, 18 serotypes and another three candidates (a-, b- and g-cross-reactive) were found in the 'S. milleri' group. Of the 248 strains tested, 197 were serotypable, and 23 strains carried two type antigens. Generally, the Ottens I, II, III (serotype f), IV and Osano IV antigens, often together with the Lancefield group F antigen, were found in S. anginosus and S. constellatus. In addition, the serotype a, c, d, e and k antigens with the group A, C or G antigen were distributed in S. anginosus, the serotype b antigen in S. constellatus and the g, h, i, j, Osano I, II and III antigens in S. intermedius. Twenty-five of the untypable strains were Lancefield groupable (mostly F).

A total of 18 'Streptococcus milleri' strains including the ATCC type strains of Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedius were compared with Streptococcus oralis ATCC10557 for their ability to induce infective endocarditis in catheterized rats. Three days after intravenous injection of 10(8) colony-forming units all 8 S. anginosus strains tested produced infective vegetations and bacteremia in almost all rats whereas 5 S. constellatus strains and the S. oralis strain produced infective vegetations and bacteremia less frequently and 5 S. intermedius strains only occasionally. The vegetations infected with the S. anginosus strains harbored microbial cells in significantly higher numbers that those with the other strains. No strong correlation was found between the endocardial infectivity and platelet-aggregating capacity of these strains. The platelet-aggregating strains were members of the Lancefield groups F and G or ungroupable but not of group A or C.

Carbohydrate antigens of the serotype k/Lancefield group G "Streptococcus milleri" were extracted by autoclaving whole cells of the type k reference strain Streptococcus anginosus K214-2K. The type k and group G antigen molecules are separated from each other and partially purified by a DEAE-Sephadex A25 column chromatography followed by a Sephadex G-100 gel filtration. In the double diffusion and the immunoelectrophoresis, the type k and group G antigen preparations obtained yielded single bands with their homologous antisera respectively. The type k antigen preparation contained principally glycerol, rhamnose, ribitol, galactose and glucose in a molar ratio of 0.54:1.20:0.43:0.33:1.00. The quantitative precipitin inhibition test indicated that beta(1-6)glucosyl-glucose (gentiobiose) sequence played a major role in immunodeterminant structure. Thus, the type k antigen of "S. milleri" appears to be a new carbohydrate type antigen that is chemically different from any Ottens type antigen. In contrast, the group G antigen preparation contained high proportion of rhamnose in addition to glucose, N-acetylglucosamine and N-acetylgalactosamine in a molar ratio of 6.45:1.00:0.24:1.15, and the rhamnose residue was involved in the immunodominant epitope, being in good agreement with the previously proposed chemical structure of the group antigen.

Carbohydrate antigens of the serotype c/Lancefield group C "Streptococcus milleri" were extracted by autoclaving whole cells of the type c reference strain K51Y. The type c and group C antigen molecules were separated and partially purified by a DEAE-Sephadex A-25 column chromatography followed by Sephadex G-100 gel filtration. The purified type c antigen and group C antigen were homogeneous in the double diffusion and in the immunoelectrophoresis. The type c antigen was composed principally of glycerol, rhamnose, glucose and N-acetylglucosamine in a molar ratio of 0.22:0.27:1.00:0.48. The quantitative precipitin inhibition test indicated that N-acetylglucosamine played a major role in immunodeterminant structure. Thus, the type c antigen of "S. milleri" is a new carbohydrate type antigen and is immunochemically different from the Ottens-type antigen III found occasionally in group C streptococci. In contrast, the group C antigen preparation contained a high proportion of N-acetylgalactosamine in addition to glycerol, rhamnose, glucose and N-acetylglucosamine, and the N-acetylgalactosamine residue was involved in the immunodominant epitope, being in good agreement with the previously proposed chemical structure of the group antigen. N-acetylgalactosamine was detected in the autoclaved extracts of a nontypeable/group C strain but not of a type c/ungroupable strain.

Of the 29 'Streptococcus milleri' strains tested, all thirteen Streptococcus intermedius (DNA homology group 2) strains but none of the thirteen Streptococcus anginosus (group 1) strains produced beta-N-acetylglucosaminidase, beta-N-acetylgalactosaminidase, alpha-N-acetylneuraminidase, beta-galactosidase, alpha-glucosidase, and hyaluronidase. The three Streptococcus constellatus (group 3) strains produced only the latter two. Glycosidase production divided 274 clinical isolates into 103 S. anginosus, 101 S. intermedius, and 70 S. constellatus strains. Generally, strains of S. anginosus and S. intermedius were non-beta-haemolytic. API II and biotype Ia (lactose positive), but the former contained almost all API III strains and belonged to Lancefield group A/serotype a (A/a), -/b, C/c, -/d, -/e, F/f or G/k, and the latter included most of biotype IId (lactose negative) and serovar -/g, -/h, -/i or -/j. S constellatus strains were beta-, alpha- or gamma-haemolytic, of API I or II but mostly biotype Ib (lactose negative), and of F/- or -/b. S. intermedius was a major member of the oral isolates. Non-oral isolates were virtually all S. anginosus (mainly urogenital isolates) or S. constellatus (the other systemic isolates).

Ninety-one Streptococcus milleri strains isolated from various systemic purulent lesions of 68 patients were examined by physiological and serological tests. Most strains formed a smooth colony (66 strains), did not form spontaneous aggregation of cells in BHI broth culture (79), were non-beta-haemolytic (alpha-35 or non-41), and belonged to biotype Ia (49) or Ib (34) and to API taxa S. milleri I (41) or II (38). Almost all of the beta-haemolytic strains as well as two-fifths of the non-beta-haemolytic belonged to API taxon I; strains of API taxa II and III were non-beta-haemolytic and non-haemolytic, respectively. Two-fifths (38) of the isolates belonged to one of eight serotypes, a-g and k, and more than half (47) to Lancefield groups A, C, F or G, the most frequent being type b (19) and group F (33). Fifteen strains carried simultaneously type a/group A, b/C, c/C, e/G, f/F or k/G antigens. Nineteen were neither typable nor groupable. All the 38 serotypable isolates were non-beta-haemolytic and not members of API taxon III, and were serologically and physiologically similar to oral S. milleri. The isolates from various infected sites--sputum, thorax, abdomen, urogenitalia, skin, eye and dental--exhibited distinct combinations of biological and serological properties. These results suggest that serotyping, haemolytic properties and API taxon, and their combinations, would be useful methods to trace oral S. milleri in systemic infections.

Cells of representative strains of oral "Streptococcus milleri" firmly adhered to glass surfaces when grown in glucose broths as well as in fructose and sucrose broths. Cellular adherence occurred on saliva-coated glass surfaces as well as uncoated surfaces, but the cells of only a few (6 of 69) tested adherent strains agglutinated upon the addition of human whole-saliva supernatant. Thus, the firm adherence of growing "S. milleri" cells is independent of sucrose and salivary macromolecules. Two macroscopic forms of cell adherence were observed: one was a coarse-granule type and one was a tiny-granule type covered with a thin homogeneous membranous material. Scanning electron microscopy revealed that, in both types, a stringy substance interconnected the cells and connected the cells to glass surfaces, with amorphous flocklike materials present in the intercellular space. Of the 154 tested strains, 128 were adherent, of which 90 were firmly and extensively (+2 or +3) adherent. Most strains of the serovars f/F, g, h, i, j, g-, and gj- were extensively adherent. Generally, cells of the more strongly adherent strains were more hydrophobic and spontaneously aggregating. However, there also existed a few hydrophilic and nonaggregating but extensively adherent strains. The presence of trypsin or pronase completely inhibited the adherence of some strains (mostly nonaggregating) but did not at all inhibit that of others (mostly aggregating). The adhering groups did not significantly differ in their cell surface hydrophobicities. Therefore, at least two factors, one proteinaceous and one nonproteinaceous, appear to be principally involved in the firm surface adherence of "S. milleri."

Of 158 oral Streptococcus milleri strains, 46 exhibited cellular coaggregation with the reagent strains of the actinomyces coaggregation groups A, B, and/or E. All but 1 of the 33 serotype b, e, f/F, and k/G strains belonged to streptococcus coaggregation group 2, and only 14 strains of limited seroclasses (g, i, Lancefield group F, or untypeable) appeared to be members of group 5, 3, or 4 (10, 3, and 1 strain, respectively). Thus, S. milleri infrequently exhibits lactose-inhibitable coaggregation with actinomyces.

Carbohydrate antigens of the serotype k/Lancefield group G "Streptococcus milleri" were extracted by autoclaving whole cells of the type k reference strain Streptococcus anginosus K214-2K. The type k and group G antigen molecules are separated from each other and partially purified by a DEAE-Sephadex A-25 column chromatography followed by a Sephadex G-100 gel filtration. In the double diffusion and the immunoelectrophoresis, the type k and group G antigen preparations obtained yielded single bands with their homologous antisera respectively. The type k antigen preparation contained principally glycerol, rhamnose, ribitol, galactose and glucose in a molar ratio of 0.54:1.20:0.43:0.33:1.00. The quantitative precipitin inhibition test indicated that β(1-6)glucosyl-glucose (gentiobiose) sequence played a major role in immunodeterminant structure. Thus, the type k antigen of "S. milleri" appears to be a new carbohydrate type antigen that is chemically different from any Ottens type antigen. In contrast, the group G antigen preparation contained high proportion of rhamnose in addition to glucose, N-acetylglucosamine and N-acetylgalactosamine in a molar ratio of 6.45:1.00:0.24:1.15, and the rhamnose residue was involved in the immunodominant epitope, being in good agreement with the previously proposed chemical structure of the group antigen. [ABSTRACT FROM AUTHOR]

Carbohydrate antigens of the serotype c/Lancefield group C "Streptococcus milleri" were extracted by autoclaving whole cells of the type c reference strain K51 Y. The type c and group C antigen molecules were separated and partially purified by a DEAE-Sephadex A-25 column chromatogiaphy followed by Sephadex G-100 gel filtration, The purified type c antigen and group C antigen were homogeneous in the double diffusion and in the immunoelectophoresis. The type C antigen was composed principally of glycerol, rhamnose, glucose and N-acetylglucosamine in a molar ratio of 0.22; 0.27: 100: 0.48. The quantitative precipitin inhibition test indicated that N-acetylglucosamine played a major role in immunodeterminant structure. Thus, tile type c antigen of "S. milleri" is a new carbohydrate type antigen and is immunochemically different from the Ottens-type antigen III found occasionally in group C streptococci. In contrast, the group C antigen preparation contained a high proportion of N-acctylgalactosamme in addition to glycerol, rhamnose, glucose and N-acetylglucosamine, and the N- acetylgalactosamine , residue was involved in the immunodominant epitope, being in good agreement with the previously proposed chemical structure of the group antigen N-acetylgalactosamine was detected in the autoclaved extracts of a nontypeable/group C strain but not of a type c/ungroupable strain. [ABSTRACT FROM AUTHOR]