Background. Ventilator-associated pneumonia (VAP) is a leading cause of morbidity and mortality in patients hospitalized in intensive care units. Rec

Actinobacillus actinomycetemcomitans , a gram-negative bacterium isolated from the human mouth, has been implicated in the pathogenesis of early-onset periodontitis. Primary isolates cultured from subgingival plaque exhibit an adherent, rough colony phenotype which spontaneously converts to a nonadherent, smooth phenotype upon in vitro subculture. The rough colony variant produces abundant fimbriae and autoaggregates, while the smooth colony variant is planktonic and produces scant fimbriae. To begin to understand the significance of colony variation in biofilm formation by A. actinomycetemcomitans , outer membrane protein profiles of four isogenic rough and smooth colony variants were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two proteins with relative molecular masses of 43 and 20 kDa were expressed by the rough colony variants exclusively. Expression of these proteins was not found to be dependent on growth phase, oxygen tension, or type of complex medium. N-terminal amino acid sequences of these proteins obtained by Edman degradation were compared with sequences from the University of Oklahoma A. actinomycetemcomitans genome database. Two contiguous open reading frames (ORFs) encoding proteins having sequence homology with these proteins were identified. The 43-kDa protein (RcpA [rough colony protein A]) was similar to precursor protein D of the general secretion pathway of gram-negative bacilli, while the 20-kDa protein (RcpB [rough colony protein B]) appeared to be unique. The genes encoding these proteins have been cloned from A. actinomycetemcomitans 283 and sequenced. A BLASTX (gapped BLAST) search of the surrounding ORFs revealed homology with other fimbria-related proteins. These data suggest that the genes encoding the 43-kDa ( rcpA ) and 20-kDa ( rcpB ) proteins may be functionally related to each other and to genes that may encode fimbria-associated proteins.

Background: Prolonged induction of excessive levels of inflammatory mediators contributes to the pathogenesis of chronic disease states, such as periodontitis. It is thus important to develop safe and effective anti‐inflammatory strategies for therapeutic reasons. In this study, we determined the ability of aqueous extracts from elder flower (Sambucus nigra) to inhibit the proinflammatory activity of major virulence factors from the periodontal pathogens Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans.Methods: Monocytes/macrophages or neutrophils were incubated with whole cells of P. gingivalis, A. actinomycetemcomitans, or purified components thereof (lipopolysaccharide and fimbriae) in the absence or presence of elder flower extract and were assayed for cytokine production, integrin activation, or induction of the oxidative burst.Results: The elder flower extract was found to potently inhibit all proinflammatory activities tested. Investigation of the underlying mechanisms revealed that the anti‐inflammatory extract inhibited activation of the nuclear transcription factor κB and of phosphatidylinositol 3‐kinase.Conclusion: The elder flower extract displays useful anti‐inflammatory properties that could be exploited therapeutically for the control of inflammation in human periodontitis.

Chronic maxillary sinusitis is a chronic inflammatory condition in which the role of microbial infection remains undefined. Bacteria have been isolated from chronically inflamed sinuses; however, their role in the chronicity of inflammation is unknown. The objective of this study was to determine whether bacteria are present in clinical samples from chronic maxillary sinusitis and to assess the diversity of the flora present. Washes and/or tissue samples from endoscopic sinus surgery on 11 patients with chronic maxillary sinusitis were subjected to PCR amplification of bacterial 16S rDNA using three universal primer pairs, followed by cloning and sequencing. The samples were also assessed for the presence of bacteria and fungi by conventional culture methods. Viable bacteria and/or bacterial 16S rDNA were detected from maxillary sinus samples of five of the 11 patients examined (45 %). Three sinus samples were positive by both PCR and culture methods, one was positive only by PCR, and one only by culture. Thirteen bacterial species were identified: Abiotrophia defectiva, Enterococcus avium, Eubacterium sp., Granulicatella elegans, Neisseria sp., Prevotella sp., Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Stenotrophomonas maltophilia, Streptococcus gordonii, Streptococcus mitis/Streptococcus oralis and Streptococcus sp. Fungi were not detected. In one patient Streptococcus mitis/Streptococcus oralis, and in another patient Pseudomonas aeruginosa, were detected from both the sinus and the oral cavity using species-specific PCR primers. These results suggest that both aerobic and anaerobic bacteria can be detected in nearly half of chronic maxillary sinusitis cases.

α-Amylase-binding streptococci (ABS) are a heterogeneous group of commensal oral bacterial species that comprise a significant proportion of dental plaque microfloras. Salivary α-amylase, one of the most abundant proteins in human saliva, binds to the surface of these bacteria via specific surface-exposed α-amylase-binding proteins. The functional significance of α-amylase-binding proteins in oral colonization by streptococci is important for understanding how salivary components influence oral biofilm formation by these important dental plaque species. This review summarizes the results of an extensive series of studies that have sought to define the molecular basis for α-amylase binding to the surface of the bacterium as well as the biological significance of this phenomenon in dental plaque biofilm formation.