Streptococcus pyogenes: A species of gram-positive, coccoid bacteria isolated from skin lesions, blood, inflammatory exudates, and the upper respiratory tract of humans. It is a group A hemolytic Streptococcus that can cause SCARLET FEVER and RHEUMATIC FEVER.Streptococcus: A genus of gram-positive, coccoid bacteria whose organisms occur in pairs or chains. No endospores are produced. Many species exist as commensals or parasites on man or animals with some being highly pathogenic. A few species are saprophytes and occur in the natural environment.Virulence: The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.Streptococcus mutans: A polysaccharide-producing species of STREPTOCOCCUS isolated from human dental plaque.Streptococcus bovis: A species of gram-positive, coccoid bacteria commonly found in the alimentary tract of cows, sheep, and other ruminants. It occasionally is encountered in cases of human endocarditis. This species is nonhemolytic.Streptococcus thermophilus: A species of thermophilic, gram-positive bacteria found in MILK and milk products.Streptococcus pneumoniae: A gram-positive organism found in the upper respiratory tract, inflammatory exudates, and various body fluids of normal and/or diseased humans and, rarely, domestic animals.Streptococcus gordonii: A species of gram-positive, facultatively anaerobic bacteria in the family STREPTOCOCCACEAE. It is a normal inhabitant of the human oral cavity, and causes DENTAL PLAQUE and ENDOCARDITIS. It is being investigated as a vehicle for vaccine delivery.Virulence Factors: Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: TOXINS, BIOLOGICAL and surface adhesion molecules that effect the ability of the microorganism to invade and colonize a host. (From Davis et al., Microbiology, 4th ed. p486)Streptococcus sobrinus: A species of gram-positive, coccoid bacteria isolated from the human tooth surface. Strains have been shown to be cariogenic in experimental animals and may be associated with human dental caries.Bacterial Proteins: Proteins found in any species of bacterium.DextranaseBacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Bacterial Adhesion: Physicochemical property of fimbriated (FIMBRIAE, BACTERIAL) and non-fimbriated bacteria of attaching to cells, tissue, and nonbiological surfaces. It is a factor in bacterial colonization and pathogenicity.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Adhesins, Bacterial: Cell-surface components or appendages of bacteria that facilitate adhesion (BACTERIAL ADHESION) to other cells or to inanimate surfaces. Most fimbriae (FIMBRIAE, BACTERIAL) of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (BIOFILMS) is distinct from protein adhesin.Streptococcus agalactiae: A bacterium which causes mastitis in cattle and occasionally in man.Mouth: The oval-shaped oral cavity located at the apex of the digestive tract and consisting of two parts: the vestibule and the oral cavity proper.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Streptococcal Infections: Infections with bacteria of the genus STREPTOCOCCUS.Streptococcus suis: A species of STREPTOCOCCUS isolated from pigs. It is a pathogen of swine but rarely occurs in humans.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Streptococcus mitis: A species of gram-positive, coccoid bacteria commensal in the respiratory tract.Genes, Bacterial: The functional hereditary units of BACTERIA.Streptococcus equi: A species of gram-positive, coccoid bacteria isolated from abscesses in submaxillary glands and mucopurulent discharges of the upper respiratory tract of horses. This organism belongs to Group C streptococci with regards to antigen response and is known to cause strangles. The subspecies S. zooepidemicus is also considered a pathogen of horses.Gram-Positive Bacteria: Bacteria which retain the crystal violet stain when treated by Gram's method.Streptococcus oralis: A species of gram-positive, coccoid bacteria that is numerous in the mouth and throat. It is a common cause of endocarditis and is also implicated in dental plaque formation.Gram-Negative Bacteria: Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Streptococcus Phages: Viruses whose host is Streptococcus.Pneumococcal Infections: Infections with bacteria of the species STREPTOCOCCUS PNEUMONIAE.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Serotyping: Process of determining and distinguishing species of bacteria or viruses based on antigens they share.Enterococcus faecalis: A species of gram-positive, coccoid bacteria commonly isolated from clinical specimens and the human intestinal tract. Most strains are nonhemolytic.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Streptolysins: Exotoxins produced by certain strains of streptococci, particularly those of group A (STREPTOCOCCUS PYOGENES), that cause HEMOLYSIS.Hemolysin Proteins: Proteins from BACTERIA and FUNGI that are soluble enough to be secreted to target ERYTHROCYTES and insert into the membrane to form beta-barrel pores. Biosynthesis may be regulated by HEMOLYSIN FACTORS.Microbial Sensitivity Tests: Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).Genome, Bacterial: The genetic complement of a BACTERIA as represented in its DNA.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Bacteria, AnaerobicBacterial Outer Membrane Proteins: Proteins isolated from the outer membrane of Gram-negative bacteria.Bacterial Toxins: Toxic substances formed in or elaborated by bacteria; they are usually proteins with high molecular weight and antigenicity; some are used as antibiotics and some to skin test for the presence of or susceptibility to certain diseases.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Quorum Sensing: A phenomenon where microorganisms communicate and coordinate their behavior by the accumulation of signaling molecules. A reaction occurs when a substance accumulates to a sufficient concentration. This is most commonly seen in bacteria.Bacterial Capsules: An envelope of loose gel surrounding a bacterial cell which is associated with the virulence of pathogenic bacteria. Some capsules have a well-defined border, whereas others form a slime layer that trails off into the medium. Most capsules consist of relatively simple polysaccharides but there are some bacteria whose capsules are made of polypeptides.Colony Count, Microbial: Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.Staphylococcus aureus: Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Pseudomonas aeruginosa: A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. aeruginosa is a major agent of nosocomial infection.Biofilms: Encrustations, formed from microbes (bacteria, algae, fungi, plankton, or protozoa) embedding in extracellular polymers, that adhere to surfaces such as teeth (DENTAL DEPOSITS); PROSTHESES AND IMPLANTS; and catheters. Biofilms are prevented from forming by treating surfaces with DENTIFRICES; DISINFECTANTS; ANTI-INFECTIVE AGENTS; and antifouling agents.Polysaccharides, Bacterial: Polysaccharides found in bacteria and in capsules thereof.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Gene Deletion: A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.Drug Resistance, Bacterial: The ability of bacteria to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).RNA, Bacterial: Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.Host-Pathogen Interactions: The interactions between a host and a pathogen, usually resulting in disease.Escherichia coli Infections: Infections with bacteria of the species ESCHERICHIA COLI.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Bacteria, AerobicDental Plaque: A film that attaches to teeth, often causing DENTAL CARIES and GINGIVITIS. It is composed of MUCINS, secreted from salivary glands, and microorganisms.Bacterial Typing Techniques: Procedures for identifying types and strains of bacteria. The most frequently employed typing systems are BACTERIOPHAGE TYPING and SEROTYPING as well as bacteriocin typing and biotyping.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Fimbriae, Bacterial: Thin, hairlike appendages, 1 to 20 microns in length and often occurring in large numbers, present on the cells of gram-negative bacteria, particularly Enterobacteriaceae and Neisseria. Unlike flagella, they do not possess motility, but being protein (pilin) in nature, they possess antigenic and hemagglutinating properties. They are of medical importance because some fimbriae mediate the attachment of bacteria to cells via adhesins (ADHESINS, BACTERIAL). Bacterial fimbriae refer to common pili, to be distinguished from the preferred use of "pili", which is confined to sex pili (PILI, SEX).Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.Bacteriological Techniques: Techniques used in studying bacteria.Genomic Islands: Distinct units in some bacterial, bacteriophage or plasmid GENOMES that are types of MOBILE GENETIC ELEMENTS. Encoded in them are a variety of fitness conferring genes, such as VIRULENCE FACTORS (in "pathogenicity islands or islets"), ANTIBIOTIC RESISTANCE genes, or genes required for SYMBIOSIS (in "symbiosis islands or islets"). They range in size from 10 - 500 kilobases, and their GC CONTENT and CODON usage differ from the rest of the genome. They typically contain an INTEGRASE gene, although in some cases this gene has been deleted resulting in "anchored genomic islands".Mutagenesis, Insertional: Mutagenesis where the mutation is caused by the introduction of foreign DNA sequences into a gene or extragenic sequence. This may occur spontaneously in vivo or be experimentally induced in vivo or in vitro. Proviral DNA insertions into or adjacent to a cellular proto-oncogene can interrupt GENETIC TRANSLATION of the coding sequences or interfere with recognition of regulatory elements and cause unregulated expression of the proto-oncogene resulting in tumor formation.Streptococcal Vaccines: Vaccines or candidate vaccines used to prevent STREPTOCOCCAL INFECTIONS.Pneumonia, Pneumococcal: A febrile disease caused by STREPTOCOCCUS PNEUMONIAE.Microbial Viability: Ability of a microbe to survive under given conditions. This can also be related to a colony's ability to replicate.Cell Wall: The outermost layer of a cell in most PLANTS; BACTERIA; FUNGI; and ALGAE. The cell wall is usually a rigid structure that lies external to the CELL MEMBRANE, and provides a protective barrier against physical or chemical agents.Pharyngitis: Inflammation of the throat (PHARYNX).Drug Resistance, Microbial: The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Streptococcus intermedius: A species of gram-positive bacteria in the STREPTOCOCCUS MILLERI GROUP. It is commonly found in the oropharynx flora and has a proclivity for abscess formation, most characteristically in the CENTRAL NERVOUS SYSTEM and LIVER.DNA, Ribosomal: DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Erythromycin: A bacteriostatic antibiotic macrolide produced by Streptomyces erythreus. Erythromycin A is considered its major active component. In sensitive organisms, it inhibits protein synthesis by binding to 50S ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins.Operon: In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.Mice, Inbred BALB CPhenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Water Microbiology: The presence of bacteria, viruses, and fungi in water. This term is not restricted to pathogenic organisms.Saliva: The clear, viscous fluid secreted by the SALIVARY GLANDS and mucous glands of the mouth. It contains MUCINS, water, organic salts, and ptylin.Phagocytosis: The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).Salmonella typhimurium: A serotype of Salmonella enterica that is a frequent agent of Salmonella gastroenteritis in humans. It also causes PARATYPHOID FEVER.Plant Diseases: Diseases of plants.Exotoxins: Toxins produced, especially by bacterial or fungal cells, and released into the culture medium or environment.Fimbriae Proteins: Proteins that are structural components of bacterial fimbriae (FIMBRIAE, BACTERIAL) or sex pili (PILI, SEX).Genetic Complementation Test: A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.Glucosyltransferases: Enzymes that catalyze the transfer of glucose from a nucleoside diphosphate glucose to an acceptor molecule which is frequently another carbohydrate. EC 2.4.1.-.Listeria monocytogenes: A species of gram-positive, rod-shaped bacteria widely distributed in nature. It has been isolated from sewage, soil, silage, and from feces of healthy animals and man. Infection with this bacterium leads to encephalitis, meningitis, endocarditis, and abortion.Anti-Infective Agents: Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.DNA Transposable Elements: Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.Transformation, Bacterial: The heritable modification of the properties of a competent bacterium by naked DNA from another source. The uptake of naked DNA is a naturally occuring phenomenon in some bacteria. It is often used as a GENE TRANSFER TECHNIQUE.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Pharynx: A funnel-shaped fibromuscular tube that conducts food to the ESOPHAGUS, and air to the LARYNX and LUNGS. It is located posterior to the NASAL CAVITY; ORAL CAVITY; and LARYNX, and extends from the SKULL BASE to the inferior border of the CRICOID CARTILAGE anteriorly and to the inferior border of the C6 vertebra posteriorly. It is divided into the NASOPHARYNX; OROPHARYNX; and HYPOPHARYNX (laryngopharynx).Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Dental Caries: Localized destruction of the tooth surface initiated by decalcification of the enamel followed by enzymatic lysis of organic structures and leading to cavity formation. If left unchecked, the cavity may penetrate the enamel and dentin and reach the pulp.Bacteriocins: Substances elaborated by specific strains of bacteria that are lethal against other strains of the same or related species. They are protein or lipopolysaccharide-protein complexes used in taxonomy studies of bacteria.Vibrio cholerae: The etiologic agent of CHOLERA.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Penicillins: A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)Actinomyces: A genus of gram-positive, rod-shaped bacteria whose organisms are nonmotile. Filaments that may be present in certain species are either straight or wavy and may have swollen or clubbed heads.Penicillin Resistance: Nonsusceptibility of an organism to the action of penicillins.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Endocarditis, Bacterial: Inflammation of the ENDOCARDIUM caused by BACTERIA that entered the bloodstream. The strains of bacteria vary with predisposing factors, such as CONGENITAL HEART DEFECTS; HEART VALVE DISEASES; HEART VALVE PROSTHESIS IMPLANTATION; or intravenous drug use.Yersinia pestis: The etiologic agent of PLAGUE in man, rats, ground squirrels, and other rodents.Bacterial Physiological Phenomena: Physiological processes and properties of BACTERIA.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Bacteremia: The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Nasopharynx: The top portion of the pharynx situated posterior to the nose and superior to the SOFT PALATE. The nasopharynx is the posterior extension of the nasal cavities and has a respiratory function.Bacterial Infections: Infections by bacteria, general or unspecified.N-Acetylmuramoyl-L-alanine Amidase: An autolytic enzyme bound to the surface of bacterial cell walls. It catalyzes the hydrolysis of the link between N-acetylmuramoyl residues and L-amino acid residues in certain cell wall glycopeptides, particularly peptidoglycan. EC 3.5.1.28.Regulon: In eukaryotes, a genetic unit consisting of a noncontiguous group of genes under the control of a single regulator gene. In bacteria, regulons are global regulatory systems involved in the interplay of pleiotropic regulatory domains and consist of several OPERONS.Antibiosis: A natural association between organisms that is detrimental to at least one of them. This often refers to the production of chemicals by one microorganism that is harmful to another.Bacterial Vaccines: Suspensions of attenuated or killed bacteria administered for the prevention or treatment of infectious bacterial disease.Anaerobiosis: The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Porphyromonas gingivalis: A species of gram-negative, anaerobic, rod-shaped bacteria originally classified within the BACTEROIDES genus. This bacterium produces a cell-bound, oxygen-sensitive collagenase and is isolated from the human mouth.Cytotoxins: Substances that are toxic to cells; they may be involved in immunity or may be contained in venoms. These are distinguished from CYTOSTATIC AGENTS in degree of effect. Some of them are used as CYTOTOXIC ANTIBIOTICS. The mechanism of action of many of these are as ALKYLATING AGENTS or MITOSIS MODULATORS.Blood Bactericidal Activity: The natural bactericidal property of BLOOD due to normally occurring antibacterial substances such as beta lysin, leukin, etc. This activity needs to be distinguished from the bactericidal activity contained in a patient's serum as a result of antimicrobial therapy, which is measured by a SERUM BACTERICIDAL TEST.Staphylococcal Infections: Infections with bacteria of the genus STAPHYLOCOCCUS.Bacteriolysis: Rupture of bacterial cells due to mechanical force, chemical action, or the lytic growth of BACTERIOPHAGES.Macrolides: A group of often glycosylated macrocyclic compounds formed by chain extension of multiple PROPIONATES cyclized into a large (typically 12, 14, or 16)-membered lactone. Macrolides belong to the POLYKETIDES class of natural products, and many members exhibit ANTIBIOTIC properties.Prophages: Genomes of temperate BACTERIOPHAGES integrated into the DNA of their bacterial host cell. The prophages can be duplicated for many cell generations until some stimulus induces its activation and virulence.Streptococcus constellatus: A species of gram-positive bacteria in the STREPTOCOCCUS MILLERI GROUP. It is commonly found in the oropharnyx flora and has a proclivity for abscess formation in the upper body and respiratory tract.Bacterial Load: Measurable quantity of bacteria in an object, organism, or organism compartment.Cryptococcus neoformans: A species of the fungus CRYPTOCOCCUS. Its teleomorph is Filobasidiella neoformans.4-Butyrolactone: One of the FURANS with a carbonyl thereby forming a cyclic lactone. It is an endogenous compound made from gamma-aminobutyrate and is the precursor of gamma-hydroxybutyrate. It is also used as a pharmacological agent and solvent.Gene Transfer, Horizontal: The naturally occurring transmission of genetic information between organisms, related or unrelated, circumventing parent-to-offspring transmission. Horizontal gene transfer may occur via a variety of naturally occurring processes such as GENETIC CONJUGATION; GENETIC TRANSDUCTION; and TRANSFECTION. It may result in a change of the recipient organism's genetic composition (TRANSFORMATION, GENETIC).Macrophages: The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood MONOCYTES. Main types are PERITONEAL MACROPHAGES; ALVEOLAR MACROPHAGES; HISTIOCYTES; KUPFFER CELLS of the liver; and OSTEOCLASTS. They may further differentiate within chronic inflammatory lesions to EPITHELIOID CELLS or may fuse to form FOREIGN BODY GIANT CELLS or LANGHANS GIANT CELLS. (from The Dictionary of Cell Biology, Lackie and Dow, 3rd ed.)Aminoacyltransferases: Enzymes that catalyze the transfer of an aminoacyl group from donor to acceptor resulting in the formation of an ester or amide linkage. EC 2.3.2.
  • If a pathogenic bacterium uses a pheromone to turn on expression of a virulence factor (like a toxin), then maybe we can block this action with the inhibitor,' Federle said, cautioning that much more research will be needed before the findings could be applied to people. (chicagotribune.com)
  • After invasion of the insect host by the nematodes, bacteria produce potential virulence factors, including lipase, protease, and lipopolysaccharides in the hemocoel (for a review, see reference 26 ). (asm.org)
  • Silverwood, " Coagglutination reactions between Candida albicans and oral bacteria," Journal of Medical Microbiology, vol. (thefreedictionary.com)
  • A broad spectrum of pneumococcal virulence factors, which are adapted successfully to different host niches, is involved either predominantly in nasopharyngeal colonization or subsequently in dissemination and transmigration of host tissue barriers. (springer.com)
  • The value of molecular evolutionary analysis helps identify new drug targets, including among pneumococcal virulence factors, especially when combined with traditional molecular microbiological approaches. (medindia.net)
  • This Research Topic will focus on the molecular components involved in biofilm formation by staphylococci and streptococci, the role they play in the development, maturation and dispersal of biofilm and on the regulatory aspects of such complex processes. (frontiersin.org)
  • Molecular mechanisms of adhesion and colonisation by oral streptococci. (ncl.ac.uk)
  • Since the molecular basis of virulence of this oral commensal bacterium remains unclear, we searched the genome of S. sanguinis for previously unidentified virulence factors. (umn.edu)
  • With an ever-increasing understanding of the group A streptococcus at a molecular level, new and sophisticated vaccines are currently in human trials and the next decade holds exciting prospects for curbing group A streptococcal diseases. (scribd.com)
  • The study, published online in the April issue of Molecular Microbiology, also adds crucial new knowledge to the molecular factors that underlie the virulence of M. tuberculosis and may aid development of new, targeted treatments for the disease. (innovations-report.com)
  • Dr. Amendt's research focuses on studying the expression and regulation of transcription factor genes and signaling processes involved in craniofacial/tooth development, the molecular basis of selected human genetic disorders, and the role of stem cells and microRNAs in regulating craniofacial and regenerative medicine. (uiowa.edu)
  • In conclusion, the acquisition of factor H by pneumococci via PspC occurs via two contact sites located in SCR8-11 and SCR19-20, and factor H attached to the surface of the pneumococcus promotes adhesion to both host epithelial and endothelial cells. (jimmunol.org)
  • The bacteria that cause necrotizing fasciitis, or "flesh-eating disease"-group A Streptococcus (group A Strep)-is highly infectious and leads to more than 500,000 deaths per year. (genengnews.com)
  • At present, there is no vaccine against group A Strep, and our discovery of hidden sequence patterns has offered up a novel way to devise such a vaccine," noted lead study investigator Partho Ghosh, Ph.D., professor, and chair of UC San Diego's Department of Chemistry and Biochemistry. (genengnews.com)
  • Group A Strep brings C4BP to its surface to dampen the immune response. (genengnews.com)
  • For example, pharyngitis caused by Arcanobacterium haemolyticum can have a similar clinical syndrome as group A strep, including fever, exudative pharyngitis, and accompanying rash. (thefreedictionary.com)
  • Antibodies against six different serovars of Group A strep were attached to latex beads. (lumenlearning.com)
  • A key regulator of GAS virulence gene expression is the CovR-CovS two-component regulatory system (also known as CsrR-CsrS). (asm.org)
  • Here, we report that P. inhibens S4Sm, an alphaproteobacterium and member of the Roseobacter clade, also secretes secondary metabolites that hijack the quorum sensing ability of V. coralliilyticus RE22Sm, suppressing virulence gene expression. (asm.org)
  • 100-gene com regulon in addition to DNA uptake, including virulence. (plos.org)
  • Secondly, the requirement for and the role of virulence gene regulators identified by Signature Tagged Mutagenesis were investigated. (bl.uk)
  • In some it has already been shown that the extra secA2 gene is required for virulence. (innovations-report.com)
  • Horizontal Gene Transfer (HGT) events, initially thought to be rare in Mycobacterium tuberculosis , have recentlybeen shown to be involved in the acquisition of virulence operons in M. tuberculosis . (ias.ac.in)
  • Moreover, the luxS gene was down-regulated in bacteria treated with LF. (springer.com)
  • The bacterium uses several strategies for colonization of the respiratory tract, transcytosis through host cells, and transmigration of the blood-brain-barrier. (jimmunol.org)
  • These bacteria, which are highly pathogenic to insects, are transported by their nematode hosts into the hemocoel of the insect prey, which is killed probably via a combination of toxin action and septicemia. (asm.org)
  • Actinomycosis is caused by a family of bacteria called Actinomycetaceae that are usually found in the nose, throat, gastrointestinal and female genital tract. (medindia.net)
  • Although all propolis samples inhibited the mutans streptococci growth, it was observed a wide spectrum of action (MIC 0.90 to 8.22 µ gmL -1 ). (scielo.br)
  • Bacteria within a biofilm persist in adverse conditions, show resistance to killing by antibiotics and to host immune defences and are difficult to eradicate and treat clinically. (frontiersin.org)
  • In recent years, the discovery and development of structurally novel antibiotics with distinct mechanisms of action have become particularly important because of the emerging resistance of bacteria to all existing classes, which causes significant treatment problems around the world. (emedexpert.com)
  • Developing ways to block, rather than kill, microorganisms that cause disease is important because a growing number of bacteria have found ways to avoid antibiotics, Federle explained. (chicagotribune.com)