(1/562) Interaction of inflammatory cells and oral microorganisms. III. Modulation of rabbit polymorphonuclear leukocyte hydrolase release response to Actinomyces viscosus and Streptococcus mutans by immunoglobulins and complement.

In the absence of antiserum, rabbit polymorphonuclear leukocytes (PMNs) released lysosomal enzymes in response to Actinomyces viscosus (19246) but not to Streptococcus mutans (6715). Antibodies had a marked modulating influence on these reactions. PMN hydrolase release was significantly enhanced to both organisms when specific rabbit antiserum and isolated immunoglobulin G (IgG) were included in the incubations. Immune complex F(ab')2 fragments of IgG directed against S. mutans agglutinated bacteria. Immune complexes consisting of S. mutans and F(ab')2 fragments of IgG directed against this organism were not effective as bacteria-IgG complexes in stimulating PMN release. The intensity of the release response to bacteria-IgG complexes was also diminished when PMNs were preincubated with isolated Fc fragments derived from IgG. Fresh serum as a source of complement components had no demonstrable effect on PMN release either alone or in conjuction with antiserum in these experiments. These data may be relevant to the mechanisms and consequences of the interaction of PMNs and plaque bacteria in the pathogenesis of periodontal disease.  (+info)

(2/562) Pathogenesis of cancrum oris (noma): confounding interactions of malnutrition with infection.

This study showed that impoverished Nigerian children at risk for cancrum oris (noma) had significantly reduced plasma concentrations of zinc (< 10.8 micromol/L), retinol (< 1.05 micromol/L), ascorbate (< 11 micromol/L), and the essential amino acids, with prominently increased plasma and saliva levels of free cortisol, compared with their healthy counterparts. The nutrient deficiencies, in concert with previously reported widespread viral infections (measles, herpesviruses) in the children, would impair oral mucosal immunity. We postulate, subject to additional studies, that evolution of the oral mucosal ulcers including acute necrotizing gingivitis to noma is triggered by a consortium of microorganisms of which Fusobacterium necrophorum is a key component. Fusobacterium necrophorum elaborates several dermonecrotic toxic metabolites and is acquired by the impoverished children via fecal contamination resulting from shared residential facilities with animals and very poor environmental sanitation.  (+info)

(3/562) An Arcanobacterium (Actinomyces) pyogenes mutant deficient in production of the pore-forming cytolysin pyolysin has reduced virulence.

Pyolysin (PLO), the hemolytic exotoxin expressed by Arcanobacterium (Actinomyces) pyogenes, is a member of the thiol-activated cytolysin family of bacterial toxins. Insertional inactivation of the plo gene results in loss of expression of PLO with a concomitant loss in hemolytic activity. The plo mutant, PLO-1, has an approximately 1. 8-log10 reduction in the 50% infectious dose compared to that for wild-type A. pyogenes in a mouse intraperitoneal infection model. Studies involving cochallenge of wild-type and PLO-1 bacteria resulted in recovery of similar numbers of both strains, suggesting that PLO production is required for survival in vivo. Recombinant, His-tagged PLO (His-PLO) is cytotoxic for mouse peritoneal macrophages and J774 cells in a dose-dependent manner. Protection against challenge with A. pyogenes could be afforded by vaccination with formalin-inactivated His-PLO, suggesting that PLO is a host-protective antigen, as well as a virulence determinant.  (+info)

(4/562) Childhood actinomycosis. Report of 3 recent cases.

Three cases of childhood actinomycosis are reported, 2 with the commonest presentation of cervicofacial abscess and the third with a rarely reported superficial chest wall abscess. The importance of prompt bacteriological diagnosis and adequate treatment with surgical drainage and chemotherapy is stressed. Though in adults males are affected more frequently than females, the sexes are probably equally affected in childhood.  (+info)

(5/562) Strains of Actinomyces naeslundii and Actinomyces viscosus exhibit structurally variant fimbrial subunit proteins and bind to different peptide motifs in salivary proteins.

Oral strains of Actinomyces spp. express type 1 fimbriae, which are composed of major FimP subunits, and bind preferentially to salivary acidic proline-rich proteins (APRPs) or to statherin. We have mapped genetic differences in the fimP subunit genes and the peptide recognition motifs within the host proteins associated with these differential binding specificities. The fimP genes were amplified by PCR from Actinomyces viscosus ATCC 19246, with preferential binding to statherin, and from Actinomyces naeslundii LY7, P-1-K, and B-1-K, with preferential binding to APRPs. The fimP gene from the statherin-binding strain 19246 is novel and has about 80% nucleotide and amino acid sequence identity to the highly conserved fimP genes of the APRP-binding strains (about 98 to 99% sequence identity). The novel FimP protein contains an amino-terminal signal peptide, randomly distributed single-amino-acid substitutions, and structurally different segments and ends with a cell wall-anchoring and a membrane-spanning region. When agarose beads with CNBr-linked host determinant-specific decapeptides were used, A. viscosus 19246 bound to the Thr42Phe43 terminus of statherin and A. naeslundii LY7 bound to the Pro149Gln150 termini of APRPs. Furthermore, while the APRP-binding A. naeslundii strains originate from the human mouth, A. viscosus strains isolated from the oral cavity of rat and hamster hosts showed preferential binding to statherin and contained the novel fimP gene. Thus, A. viscosus and A. naeslundii display structurally variant fimP genes whose protein products are likely to interact with different peptide motifs and to determine animal host tropism.  (+info)

(6/562) Blastogenic response of human lymphocytes to oral bacterial antigens: comparison of individuals with periodontal disease to normal and edentulous subjects.

Cell-mediated immunity in humans to antigens derived from oral plaque bacteria was investigated by using the lymphocyte blastogenesis assay. Subjects with varying severities of periodontal disease including normal, gingivitis, periodontitis, and edentulous were compared. Mononuclear leukocytes were separated from peripheral blood and cultured with antigens prepared by sonication of Actinomyces viscosus (AV), Actinomyces naeslundii (AN), Veillonella alcalescens (VA), Leptotrichia buccalis (LB), Bacteroides melaninogenicus (BM), and homologous dental plaque (DP). The lymphocyte response of subjects with gingivitis or periodontitis was significantly greater than that of normal subjects to antigens of AV, AN, and DP, but did not differ from the response of edentulous subjects. Periodontitis subjects were significantly more reactive than edentulous and normal subjects in response to VA, LB, and BM. These findings suggest that the tested gram-negative bacteria and the host response they evoke are associated with advanced periodontal destruction.  (+info)

(7/562) Cell wall-anchored CshA polypeptide (259 kilodaltons) in Streptococcus gordonii forms surface fibrils that confer hydrophobic and adhesive properties.

It has been shown previously that inactivation of the cshA gene, encoding a major cell surface polypeptide (259 kDa) in the oral bacterium Streptococcus gordonii, generates mutants that are markedly reduced in hydrophobicity, deficient in binding to oral Actinomyces species and to human fibronectin, and unable to colonize the oral cavities of mice. We now show further that surface fibrils 60.7 +/- 14.5 nm long, which are present on wild-type S. gordonii DL1 (Challis) cells, bind CshA-specific antibodies and are absent from the cell surfaces of cshA mutants. To more precisely determine the structural and functional properties of CshA, already inferred from insertional-mutagenesis experiments, we have cloned the entire cshA gene into the replicative plasmid pAM401 and expressed full-length CshA polypeptide on the cell surface of heterologous Enterococcus faecalis JH2-2. Enterococci expressing CshA exhibited a 30-fold increase in cell surface hydrophobicity over E. faecalis JH2-2 carrying the pAM401 vector alone and 2.4-fold-increased adhesion to human fibronectin. CshA expression in E. faecalis also promoted cell-cell aggregation and increased the ability of enterococci to bind Actinomyces naeslundii cells. Electron micrographs of negatively stained E. faecalis cells expressing CshA showed peritrichous surface fibrils 70.3 +/- 9.1 nm long that were absent from control E. faecalis JH2-2(pAM401) cells. The fibrils bound CshA-specific antibodies, as detected by immunoelectron microscopy, and the antibodies inhibited the adhesion of E. faecalis cells to fibronectin. The results demonstrate that the CshA polypeptide is the structural and functional component of S. gordonii adhesive fibrils, and they provide a molecular basis for past correlations of surface fibril production, cell surface hydrophobicity, and adhesion in species of oral "sanguis-like" streptococci.  (+info)

(8/562) Bacterial flora of liver abscesses in feedlot cattle fed tylosin or no tylosin.

Bacterial flora of liver abscesses from cattle fed tylosin or no tylosin and susceptibilities of the predominant bacterial isolates to tylosin and other antimicrobial compounds were determined. Abscessed livers were collected at slaughter from cattle originating from feedlots that had fed tylosin (n = 36) or no tylosin (n = 41) for at least 2 yr, and segments of livers with one or two intact abscesses were transported to the laboratory. Abscesses were cultured for anaerobic and facultative bacteria. Fusobacterium necrophorum, either as single culture or mixed with other bacteria, was isolated from all abscesses. The incidence of subsp. necrophorum, as part of the mixed infection, was lower (P < .05) in the tylosin group than in the no-tylosin group (33 vs 61%). However, the incidence of Actinomyces pyogenes was higher (P < .01) in the tylosin group than in the no-tylosin group (53 vs 10%). Totals of 119 F. necrophorum and 21 A. pyogenes isolates were used for determinations of susceptibilities to bacitracin, oxytetracycline, chlortetracycline, lasalocid, monensin, tylosin, tilmicosin, and virginiamycin. The minimum inhibitory concentrations (MIC) of antibiotics were determined with a broth microdilution method. The mean MIC of tylosin for F. necrophorum and A. pyogenes were not different between isolates from tylosin and no-tylosin groups. We concluded that continuous feeding of tylosin did not induce resistance in F. necrophorum or A. pyogenes. Also, the higher incidence of mixed infection of F. necrophorum and A. pyogenes in liver abscesses of tylosin-fed cattle suggests a potential synergistic interaction between the two organisms in causing liver abscesses.  (+info)

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