Interspecies competition in oral biofilms mediated by Streptococcus gordonii extracellular deoxyribonuclease SsnA.

Extracellular DNA (eDNA) is a key component of many microbial biofilms including dental plaque. However, the roles of extracellular deoxyribonuclease (DNase) enzymes within biofilms are poorly understood. Streptococcus gordonii is a pioneer colonizer of dental plaque.

Staphylococcal DNA Repair Is Required for Infection.

To cause infection, must withstand damage caused by host immune defenses. However, the mechanisms by which staphylococcal DNA is damaged and repaired during infection are poorly understood. Using a panel of transposon mutants, we identified the operon as being important for the survival of in whole human blood.

Concerted functions of Streptococcus gordonii surface proteins PadA and Hsa mediate activation of human platelets and interactions with extracellular matrix.

A range of Streptococcus bacteria are able to interact with blood platelets to form a thrombus (clot). Streptococcus gordonii is ubiquitous within the human oral cavity and amongst the common pathogens isolated from subjects with infective endocarditis. Two cell surface proteins, Hsa and Platelet adherence protein A (PadA), in S.

In vivo model for microbial invasion of tooth root dentinal tubules.

Objective Bacterial penetration of dentinal tubules via exposed dentine can lead to root caries and promote infections of the pulp and root canal system. The aim of this work was to develop a new experimental model for studying bacterial invasion of dentinal tubules within the human oral cavity. Material and Methods Sections of human root dentine were mounted into lower oral appliances that were worn by four human subjects for 15 d.

Transcriptome analysis of Streptococcus gordonii Challis DL1 indicates a role for the biofilm-associated fruRBA operon in response to Candida albicans.

Multiple levels of interkingdom signaling have been implicated in maintaining the ecological balance between Candida albicans and commensal streptococci to assure a state of oral health. To better understand the molecular mechanisms involved in the initial streptococcal response to the presence of C. albicans that can initiate oral surface colonization and biofilm formation, hypha-forming cells were incubated with Streptococcus gordonii cells for 30 min to assess the streptococcal transcriptome response.

Collagen-like peptide sequences inhibit bacterial invasion of root dentine.

Aim: To investigate the effects of peptides derived from the sequence of collagen to inhibit penetration of human or bovine dentine by species of streptococci and enterococci.

Methodology: Blocks of human or bovine root dentine were infected for 14 days with bacterial cultures, in the presence or absence of various collagen-like peptide sequences. Invasion of dentinal tubules was determined from microscopic images of histochemically stained dentine thin sections.

Group B Streptococcus pili mediate adherence to salivary glycoproteins.

Group B Streptococcus (GBS) is a leading cause of neonatal sepsis, pneumonia and meningitis, and is responsible for a rising number of severe invasive infections in adults. For all disease manifestations, colonisation is a critical first step. GBS has frequently been isolated from the oropharynx of neonates and adults.

Pneumococcal neuraminidase A: an essential upper airway colonization factor for Streptococcus pneumoniae.

Streptococcus pneumoniae colonizes the upper respiratory tract from where the organisms may disseminate systemically to cause life threatening infections. The mechanisms by which pneumococci colonize epithelia are not understood, but neuraminidase A (NanA) has a major role in promoting growth and survival in the upper respiratory tract. In this article we show that mutants of S.

Streptococcus pyogenes antigen I/II-family polypeptide AspA shows differential ligand-binding properties and mediates biofilm formation.

The streptococcal antigen I/II (AgI/II)-family polypeptides are cell wall-anchored adhesins expressed by most indigenous oral streptococci. Proteins sharing 30-40% overall amino acid sequence similarities with AgI/II-family proteins are also expressed by Streptococcus pyogenes. The S.

Pneumococcal protein PavA is important for nasopharyngeal carriage and development of sepsis.

Summary The pneumococcal cell surface protein PavA is a virulence factor associated with adherence and invasion in vitro. In this study we show in vivo that PavA is necessary for Streptococcus pneumoniae D39 colonization of the murine upper respiratory tract in a long-term carriage model, with PavA-deficient pneumococci being quickly cleared from nasopharyngeal tissue. In a pneumonia model, pavA mutants were not cleared from the lungs of infected mice and persisted to cause chronic infection, whereas wild-type pneumococci caused systemic infection.

The terminal A domain of the fibrillar accumulation-associated protein (Aap) of Staphylococcus epidermidis mediates adhesion to human corneocytes.

The opportunistic pathogen Staphylococcus epidermidis colonizes indwelling medical devices by biofilm formation but is primarily a skin resident. In many S. epidermidis strains biofilm formation is mediated by a cell wall-anchored protein, the accumulation-associated protein (Aap).

Multiple adhesin proteins on the cell surface of Streptococcus gordonii are involved in adhesion to human fibronectin.

Adhesion of bacterial cells to fibronectin (FN) is thought to be a pivotal step in the pathogenesis of invasive infectious diseases. Viridans group streptococci such as Streptococcus gordonii are considered commensal members of the oral microflora, but are important pathogens in infective endocarditis. S.

A pharmacy fellowship in a family practice training program.

An evaluation of the two-year experience since the institution of the postdoctoral pharmacy fellowship in family practice has revealed the program to be a valuable one not only for the fellows completing the program but to the departments cosponsoring this experimental training program. The two individuals who have completed the program have gone to clinical practice positions. In both academic and hospital settings, the fellow gains an understanding of the philosophical basis of family medicine while at the same time gaining specialized experience in an area of interest as well as research design and implementation.