Gram-Positive Bacteria: Bacteria which retain the crystal violet stain when treated by Gram's method.Gram-Negative Bacteria: Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.Bacteria: 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.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Anti-Infective Agents: Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Microbial Sensitivity Tests: Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).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.Phytochemicals: A broad range of biologically active compounds which occur naturally in plants having important medicinal and nutritional properties.Gram-Positive Bacterial Infections: Infections caused by bacteria that retain the crystal violet stain (positive) when treated by the gram-staining method.Bacteria, AnaerobicAnacardiaceae: The sumac plant family in the order Sapindales, subclass Rosidae, class Magnoliopsida. They are tropical and subtropical trees, shrubs, and woody vines that have resin ducts in the bark. The sap of many of the species is irritating to the skin.Fungi: A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including MUSHROOMS; YEASTS; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies.Gram-Negative Bacterial Infections: Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Gram-Positive Cocci: Coccus-shaped bacteria that retain the crystal violet stain when treated by Gram's method.Bacterial Infections: Infections by bacteria, general or unspecified.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.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.Bacterial Proteins: Proteins found in any species of bacterium.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.Disk Diffusion Antimicrobial Tests: A method where a culturing surface inoculated with microbe is exposed to small disks containing known amounts of a chemical agent resulting in a zone of inhibition (usually in millimeters) of growth of the microbe corresponding to the susceptibility of the strain to the agent.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.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.Enterococcus faecalis: A species of gram-positive, coccoid bacteria commonly isolated from clinical specimens and the human intestinal tract. Most strains are nonhemolytic.Bacillus subtilis: A species of gram-positive bacteria that is a common soil and water saprophyte.Bacteria, AerobicGentian Violet: A dye that is a mixture of violet rosanilinis with antibacterial, antifungal, and anthelmintic properties.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.Staphylococcal Infections: Infections with bacteria of the genus STAPHYLOCOCCUS.PhenazinesDNA, Ribosomal: DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Antifungal Agents: Substances that destroy fungi by suppressing their ability to grow or reproduce. They differ from FUNGICIDES, INDUSTRIAL because they defend against fungi present in human or animal tissues.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Water Microbiology: The presence of bacteria, viruses, and fungi in water. This term is not restricted to pathogenic organisms.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Gram-Negative Aerobic Bacteria: A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. This is because the cell walls of gram-negative bacteria are low in peptidoglycan and thus have low affinity for violet stain and high affinity for the pink dye safranine.Gram-Negative Anaerobic Bacteria: A large group of anaerobic bacteria which show up as pink (negative) when treated by the Gram-staining method.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.Bacterial Physiological Phenomena: Physiological processes and properties of BACTERIA.Infant, Newborn: An infant during the first month after birth.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.RNA, Bacterial: Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.Genes, Bacterial: The functional hereditary units of BACTERIA.Sulfur-Reducing Bacteria: A group of gram-negative, anaerobic bacteria that is able to oxidize acetate completely to carbon dioxide using elemental sulfur as the electron acceptor.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Seawater: The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Photosensitizing Agents: Drugs that are pharmacologically inactive but when exposed to ultraviolet radiation or sunlight are converted to their active metabolite to produce a beneficial reaction affecting the diseased tissue. These compounds can be administered topically or systemically and have been used therapeutically to treat psoriasis and various types of neoplasms.Photochemotherapy: Therapy using oral or topical photosensitizing agents with subsequent exposure to light.Rose Bengal: A bright bluish pink compound that has been used as a dye, biological stain, and diagnostic aid.Polystyrenes: Polymerized forms of styrene used as a biocompatible material, especially in dentistry. They are thermoplastic and are used as insulators, for injection molding and casting, as sheets, plates, rods, rigid forms and beads.Porphyrins: A group of compounds containing the porphin structure, four pyrrole rings connected by methine bridges in a cyclic configuration to which a variety of side chains are attached. The nature of the side chain is indicated by a prefix, as uroporphyrin, hematoporphyrin, etc. The porphyrins, in combination with iron, form the heme component in biologically significant compounds such as hemoglobin and myoglobin.Methylene Blue: A compound consisting of dark green crystals or crystalline powder, having a bronze-like luster. Solutions in water or alcohol have a deep blue color. Methylene blue is used as a bacteriologic stain and as an indicator. It inhibits GUANYLATE CYCLASE, and has been used to treat cyanide poisoning and to lower levels of METHEMOGLOBIN.Singlet Oxygen: An excited state of molecular oxygen generated photochemically or chemically. Singlet oxygen reacts with a variety of biological molecules such as NUCLEIC ACIDS; PROTEINS; and LIPIDS; causing oxidative damages.