Browsing by Author "Cook, Guy S."

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Biofilm formation by porphyromonas gingivalis and streptococcus gordonii
(1998) Cook, Guy S.; Costerton, J. William; Lamont, Richard J.
Confocal scanning laser microscopy (CSLM) was used to visualize and quantify biofilm formation by the oral bacteria Streptococcus gordonii and Porphyromonas gingivalis, A saliva-coated glass coverslip under continuous bacterial challenge and conditions of low shear force was used to investigate attachment to the salivary pellicle and also the effect of cell-cell interactions on the extent of colonization and biofilm development. S. gordonii bound to the salivary pellicle and outcompeted P. gingivalis for attachment sites. Both P. gingivalis and S. gordonii failed to establish substantial biofilm formation independently. However, biofilm formation did occur subsequent to initial adherence of P. gingivalis to S. gordonii cells deposited on the salivary pellicle. The commensal species S. gordonii may. therefore, provide an attachment substrate for colonization and biofilm accretion by the potential pathogen, P. gingivalis.
Biofilms, biomaterials and device-related infections
(2004) Costerton, J. William; Stoodley, Paul; Shirtliff, Mark E.; Pasmore, M.; Cook, Guy S.
Direct confocal microscopy studies of the bacterial colonization in vitro of a silver-coated heart valve sewing cuff
(2000) Cook, Guy S.; Costerton, J. William; Darouiche, R. O.
Discrete protein determinant directs the species-specific adherence of porphyromonas gingivalis to oral streptococci
(2001-09) Demuth, Donald R.; Irvine, Douglas C.; Costerton, J. William; Cook, Guy S.; Lamont, Richard J.
For pathogens to survive in the human oral cavity, they must identify a suitable niche in the complex multispecies biofilm that exists on oral tissues. The periodontal pathogenPorphyromonas gingivalis adheres toStreptococcus gordonii by interacting with a specific region of the streptococcal SspB polypeptide, designated BAR. However, it does not adhere to Streptococcus mutans, which expresses SpaP, a highly conserved homolog of SspB. Comparison of the predicted secondary structure of BAR with the corresponding region of SpaP suggested that the substitution of Asn for Gly1182 and Val for Pro1185 in SspB may confer a unique local structure that is not conserved in SpaP. A synthetic peptide of 26 amino acids that encompassed residues 1167 to 1193 of SspB promoted avid adherence of P. gingivalis, whereas a peptide derived from the region corresponding to BAR in SpaP was inactive. Substitution of Gly1182 and Pro1185 for Asn1182 and Val1185 in SspB by site-specific mutation generated proteins that were predicted to assume an SpaP-like secondary structure, and the purified proteins did not promote P. gingivalis adherence. Furthermore,Enterococcus faecalis strains expressing the site-specific mutants did not support adherence of P. gingivalis cells. In contrast, P. gingivalisadhered efficiently to E. faecalis strains expressing intact SspB or SspB-SpaP chimeric proteins containing BAR. These results suggest that a region of SspB consisting of 26 amino acids is sufficient to mediate the adherence of P. gingivalis to S. gordonii and that the species specificity of adherence arises from its interaction with a discrete structural determinant of SspB that is not conserved in SpaP.
Host reactions to biomaterials and their evaluation
(2004) Anderson, Jacob Michael; Cook, Guy S.; Costerton, J. William; Hanson, S. R.; Hensten-Pettersen, Arne; Jacobsen, Nils; Johnson, Richard J.; Mitchell, Richard N.; Pasmore, M.; Schoen, Frederick J.; Shirtliff, Mark E.; Stoodley, Paul
In vitro and ex vivo activities of minocycline and edta against microorganisms embedded in biofilm on catheter surfaces
(2003-10) Raad, Issam; Chatzinikolaou, Ioannis; Chaiban, Gassan; Hanna, Hend; Hachem, Ray; Dvorak, Tanya; Cook, Guy S.; Costerton, J. William
Minocycline-EDTA (M-EDTA) flush solution has been shown to prevent catheter-related infection and colonization in a rabbit model and in hemodialysis patients. We undertook this study in order to determine the activities of M-EDTA against organisms embedded in fresh biofilm (in vitro) and mature biofilm (ex vivo). For the experiment with the in vitro model, a modified Robbin's device (MRD) was used whereby 25 catheter segments were flushed for 18 h with 10(6) CFU of biofilm-producing Staphylococcus epidermidis, Staphylococcus aureus, and Candida albicans per ml. Subsequently, each of the catheter segments was incubated in one of the following solutions: (i) streptokinase, (ii) heparin, (iii) broth alone, (iv) vancomycin, (v) vancomycin-heparin, (vi) EDTA, (vii) minocycline (high-dose alternating with low-dose), or (viii) M-EDTA (low-dose minocycline alternating with high-dose minocycline were used to study the additive and synergistic activities of M-EDTA). All segments were cultured quantitatively by scrape sonication. For the experiment with the ex vivo model, 54 catheter tip segments removed from patients and colonized with bacterial organisms by roll plate were longitudinally cut into two equal segments and exposed to either saline, heparin, EDTA, or M-EDTA (with high-dose minocycline). Subsequently, all segments were examined by confocal laser electron microscopy. In the in vitro MRD model, M-EDTA (with a low concentration of minocycline) was significantly more effective than any other agent in reducing colonization of S. epidermidis, S. aureus, and C. albicans (P < 0.01). M-EDTA (with a high concentration of minocycline) eradicated all staphylococcal and C. albicans organisms embedded in the biofilm. In the ex vivo model, M-EDTA (with a high concentration of minocycline) reduced bacterial colonization more frequently than EDTA or heparin (P < 0.01). We concluded that M-EDTA is highly active in eradicating microorganisms embedded in fresh and mature biofilm adhering to catheter surfaces.
Intergeneric communication in dental plaque biofilms
(2000-12) Xie, H.; Cook, Guy S.; Costerton, J. William; Bruce, G.; Rose, T. M.; Lamont, Richard J.
Dental plaque is a complex biofilm that accretes in a series of discrete steps proceeding from a gram-positive streptococcus-rich biofilm to a structure rich in gram-negative anaerobes. This study investigated information flow between two unrelated plaque bacteria,Streptococcus cristatus and Porphyromonas gingivalis. A surface protein of S. cristatus caused repression of the P. gingivalisfimbrial gene (fimA), as determined by a chromosomalfimA promoter-lacZ reporter construct and by reverse transcription-PCR. Signaling activity was associated with a 59-kDa surface protein of S. cristatus and showed specificity for the fimA gene. Furthermore, P. gingivalis was unable to form biofilm microcolonies with S. cristatus. Thus, S. cristatus is capable of modulating virulence gene expression in P. gingivalis, consequently influencing the development of pathogenic plaque.