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Background: Orthodontic appliances such as wires and brackets received from manufacturers come unsterilized and may be contaminated with various microorganisms before being used in the mouth. In this study, we evaluated and identified the bacterial contamination on orthodontic appliances along with the disinfecting efficacy of ultraviolet (UV) light and various sterilization methods. Methods: Different orthodontic appliances were obtained from manufacturers divided into 5 sterilization methods and a control group (control, UV, dry heat and steam autoclave, ethyl alcohol, and 2% glutaraldehyde). Microbiological and DNA sequencing was performed on the appliances to identify the contaminated bacteria. Results: Bacterial contamination identified on the orthodontic appliances were Staphylococcus aureus, Staphylococcus epidermidis, Lactobacilli, Klebsiella pneumoniae, Bacillus licheniformis, and Bacillus cereus. UV sterilization method effectively prevented the bacterial growth when compared to the control (unsterilized) orthodontic appliances. Conclusion: We concluded that the orthodontic appliances received from the manufacturer showed bacterial contamination. All of the tested sterilization methods including UV light were effective in eliminating the bacterial contamination on the orthodontic appliances. Since UV light does not cause change in material properties and is cost effective with relative ease of use, its use in clinical practice for the disinfection of orthodontic appliances is suggested before placement in the mouth. [ABSTRACT FROM AUTHOR]

The Gram-negative periodontopathogen Aggregatibacter actinomycetemcomitans (Aa) binds selectively to buccal epithelial cells (BECs) of human and Old World primates by means of the outer-membrane autotransporter protein Aae. We speculated that the exposed N-terminal portion of the passenger domain of Aae would mediate binding to BECs. By using a series of plasmids that express full-length or truncated Aae proteins in Escherichia coli, we found that the BEC-binding domain of Aae was located in the N-terminal surface-exposed region of the protein, specifically in the region spanning amino acids 201-284 just upstream of the repeat region within the passenger domain. Peptides corresponding to amino acids 201-221, 222-238 and 201-240 were synthesized and tested for their ability to reduce Aae-mediated binding to BECs based on results obtained with truncated Aae proteins expressed in E. coli. BEC-binding of E. coil expressing Aae was reduced by as much as 50% by pre-treatment of BECs with a 40-mer peptide (201-240; P40). Aae was also shown to mediate binding to cultured human epithelial keratinocytes (TW2.6), OBA9 and TERT, and endothelial (HUVEC) cells. Pre-treatment of epithelial cells with P40 resulted in a dose-dependent reduction in binding and reduced the binding of both full-length and truncated Aae proteins expressed in E. coli, as well as Aae expressed in Aa. Fluorescently labelled P40 peptides reacted in a dose-dependent manner with BEC receptors. We propose that these proof-of-principle experiments demonstrate that peptides can be designed to interfere with Aa binding mediated by host-cell receptors specific for Aae adhesins. DOI 10.1099/mic.0.037606-0

Biofilms are composed of bacterial cells embedded in an extracellular polysaccharide matrix. A major component of the Escherichia coli biofilm matrix is PGA, a linear polymer of N-acetyl-D-glucosamine residues in [beta](1,6) linkage. PGA mediates intercellular adhesion and attachment of cells to abiotic surfaces. In this report, we present genetic and biochemical evidence that PGA is also a major matrix component of biofilms produced by the human periodontopathogen Actinobacillus actinomycetemcomitans and the porcine respiratory pathogen Actinobacillus pleuropneumoniae. We also show that PGA is a substrate for dispersin B, a biofilm-releasing glycosyl hydrolase produced by A. actinomycetemcomitans, and that an orthologous dispersin B enzyme is produced by A. pleuropneumoniae. We further show that A. actinomycetemcomitans PGA cross-reacts with antiserum raised against polysaccharide intercellular adhesin, a staphylococcal biofilm matrix polysaccharide that is genetically and structurally related to PGA. Our findings confirm that PGA functions as a biofilm matrix polysaccharide in phylogenetically diverse bacterial species and suggest that PGA may play a role in intercellular adhesion and cellular detachment and dispersal in A. actinomycetemcomitans and A. pleuropneumoniae biofilms.

The objective of this study is to detrmine whether alloxan-induced diabetic Lactoferrin knockout (LFKO -/- ) mice are more susceptible to periodontal disease caused by Aggregatibacter actinomycetemcomitans compared to the diabetic wild-type (WT) mice. Diabetes was induced in mice by a single dose of alloxan (60 mg/kg) injected intravenously. Mice were categorized as diabetic when blood glucose levels >250 mg/dL were measured on the 7 th day after the injection. Periodontal disease was experimentally induced by A. actinomycetemcomitans infection in alloxan induced diabetic WT and LFKO -/- mice. Fasting blood glucose levels and body weight were monitored throughout the study. At the end of the 12 th week of infection, mice were sacrificed and bone loss among the groups was estimated by measuring the distance between cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) at 12 sites on the molars. A. actinomycetemcomitans infected mice groups developed more alveolar bone loss than sham-infected animals. Diabetic LFKO -/- infected mice exhibited significant bone loss (P<0.01) and a higher mean fasting blood glucose level (P<0.05) when compared to diabetic WT infected mice. No statistically significant difference in fasting blood glucose level was found between the infected and sham-infected groups. Peripheral blood analysis at the end of the 12 th week revealed a significant reduction in the platelet counts in LFKO -/- mice when compared to WT mice. Furthermore, diabetic LFKO -/- presented with lower counts than non-diabetic LFKO -/- mice (P<0.01). In conclusion, diabetic lactoferrin deficient mice are at a higher risk of developing periodontal infection induced by A. actinomycetemcomitans when compared to diabetic WTI mice.