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.

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.

Antibodies produced by a single clone of cells.

Infections with bacteria of the species STREPTOCOCCUS PNEUMONIAE.

Gram-negative, non-motile, capsulated, gas-producing rods found widely in nature and associated with urinary and respiratory infections in humans.

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.

A polysaccharide-producing species of STREPTOCOCCUS isolated from human dental plaque.

The property of antibodies which enables them to react with some ANTIGENIC DETERMINANTS and not with others. Specificity is dependent on chemical composition, physical forces, and molecular structure at the binding site.

Short filamentous organism of the genus Mycoplasma, which binds firmly to the cells of the respiratory epithelium. It is one of the etiologic agents of non-viral primary atypical pneumonia in man.

Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).

A febrile disease caused by STREPTOCOCCUS PNEUMONIAE.

Immunoglobulins produced in a response to BACTERIAL ANTIGENS.

Infections with bacteria of the genus STREPTOCOCCUS.

A bacterium which causes mastitis in cattle and occasionally in man.

Proteins found in any species of bacterium.

Process of determining and distinguishing species of bacteria or viruses based on antigens they share.

Substances that reduce the growth or reproduction of BACTERIA.

Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).

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.

Nonsusceptibility of an organism to the action of penicillins.

Exotoxins produced by certain strains of streptococci, particularly those of group A (STREPTOCOCCUS PYOGENES), that cause HEMOLYSIS.

Sites on an antigen that interact with specific antibodies.

An acute purulent infection of the meninges and subarachnoid space caused by Streptococcus pneumoniae, most prevalent in children and adults over the age of 60. This illness may be associated with OTITIS MEDIA; MASTOIDITIS; SINUSITIS; RESPIRATORY TRACT INFECTIONS; sickle cell disease (ANEMIA, SICKLE CELL); skull fractures; and other disorders. Clinical manifestations include FEVER; HEADACHE; neck stiffness; and somnolence followed by SEIZURES; focal neurologic deficits (notably DEAFNESS); and COMA. (From Miller et al., Merritt's Textbook of Neurology, 9th ed, p111)

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.

Immunoglobulins produced in response to VIRAL ANTIGENS.

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.

A species of gram-positive, coccoid bacteria commensal in the respiratory tract.

Vaccines or candidate vaccines used to prevent infections with STREPTOCOCCUS PNEUMONIAE.

Serological reactions in which an antiserum against one antigen reacts with a non-identical but closely related antigen.

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).

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.

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)

Inbred BALB/c mice are a strain of laboratory mice that have been selectively bred to be genetically identical to each other, making them useful for scientific research and experiments due to their consistent genetic background and predictable responses to various stimuli or treatments.

A species of STREPTOCOCCUS isolated from pigs. It is a pathogen of swine but rarely occurs in humans.

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.

A group of QUINOLONES with at least one fluorine atom and a piperazinyl group.

Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.

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.

Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.

Substances elaborated by bacteria that have antigenic activity.

Deoxyribonucleic acid that makes up the genetic material of bacteria.

Viruses whose host is Streptococcus.

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.

Cells artificially created by fusion of activated lymphocytes with neoplastic cells. The resulting hybrid cells are cloned and produce pure MONOCLONAL ANTIBODIES or T-cell products, identical to those produced by the immunologically competent parent cell.

A species of HAEMOPHILUS found on the mucous membranes of humans and a variety of animals. The species is further divided into biotypes I through VIII.

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.

Polysaccharides found in bacteria and in capsules thereof.

The major immunoglobulin isotype class in normal human serum. There are several isotype subclasses of IgG, for example, IgG1, IgG2A, and IgG2B.

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).

A measure of the binding strength between antibody and a simple hapten or antigen determinant. It depends on the closeness of stereochemical fit between antibody combining sites and antigen determinants, on the size of the area of contact between them, and on the distribution of charged and hydrophobic groups. It includes the concept of "avidity," which refers to the strength of the antigen-antibody bond after formation of reversible complexes.

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.

Inflammation of the MIDDLE EAR including the AUDITORY OSSICLES and the EUSTACHIAN TUBE.

Antibodies that reduce or abolish some biological activity of a soluble antigen or infectious agent, usually a virus.

The production of ANTIBODIES by proliferating and differentiated B-LYMPHOCYTES under stimulation by ANTIGENS.

An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.

Local surface sites on antibodies which react with antigen determinant sites on antigens (EPITOPES.) They are formed from parts of the variable regions of FAB FRAGMENTS.

Interstitial pneumonia caused by extensive infection of the lungs (LUNG) and BRONCHI, particularly the lower lobes of the lungs, by MYCOPLASMA PNEUMONIAE in humans. In SHEEP, it is caused by MYCOPLASMA OVIPNEUMONIAE. In CATTLE, it may be caused by MYCOPLASMA DISPAR.

Infections with bacteria of the genus KLEBSIELLA.

The functional hereditary units of BACTERIA.

The condition of harboring an infective organism without manifesting symptoms of infection. The organism must be readily transmissible to another susceptible host.

Compounds based on ERYTHROMYCIN with the 3-cladinose replaced by a ketone. They bind the 23S part of 70S bacterial RIBOSOMES.

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.

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.

Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.

Semisynthetic broad-spectrum cephalosporin.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

Gram-negative aerobic cocci of low virulence that colonize the nasopharynx and occasionally cause MENINGITIS; BACTEREMIA; EMPYEMA; PERICARDITIS; and PNEUMONIA.

Methods used for studying the interactions of antibodies with specific regions of protein antigens. Important applications of epitope mapping are found within the area of immunochemistry.

Bacterial proteins that share the property of binding irreversibly to PENICILLINS and other ANTIBACTERIAL AGENTS derived from LACTAMS. The penicillin-binding proteins are primarily enzymes involved in CELL WALL biosynthesis including MURAMOYLPENTAPEPTIDE CARBOXYPEPTIDASE; PEPTIDE SYNTHASES; TRANSPEPTIDASES; and HEXOSYLTRANSFERASES.

The L-isomer of Ofloxacin.

A broad-spectrum cephalosporin antibiotic with a very long half-life and high penetrability to meninges, eyes and inner ears.

Antibodies which react with the individual structural determinants (idiotopes) on the variable region of other antibodies.

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.

A bacterial DNA topoisomerase II that catalyzes ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. Topoisomerase IV binds to DNA as a heterotetramer consisting 2 parC and 2 parE subunits. Topoisomerase IV is a decatenating enzyme that resolves interlinked daughter chromosomes following DNA replication.

The measurement of infection-blocking titer of ANTISERA by testing a series of dilutions for a given virus-antiserum interaction end-point, which is generally the dilution at which tissue cultures inoculated with the serum-virus mixtures demonstrate cytopathology (CPE) or the dilution at which 50% of test animals injected with serum-virus mixtures show infectivity (ID50) or die (LD50).

Invasion of the host RESPIRATORY SYSTEM by microorganisms, usually leading to pathological processes or diseases.

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.

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.

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.

A synthetic fluoroquinolone antibacterial agent that inhibits the supercoiling activity of bacterial DNA GYRASE, halting DNA REPLICATION.

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.

The sum of the weight of all the atoms in a molecule.

Naphthyridines are a class of heterocyclic organic compounds containing a naphthyridine nucleus, which is a polycyclic aromatic hydrocarbon made up of two benzene rings fused to a pyridine ring, and they have been studied for their potential pharmacological properties, including as antimicrobial, antiviral, and anticancer agents.

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.

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.

Immunologic techniques based on the use of: (1) enzyme-antibody conjugates; (2) enzyme-antigen conjugates; (3) antienzyme antibody followed by its homologous enzyme; or (4) enzyme-antienzyme complexes. These are used histologically for visualizing or labeling tissue specimens.

Semisynthetic vaccines consisting of polysaccharide antigens from microorganisms attached to protein carrier molecules. The carrier protein is recognized by macrophages and T-cells thus enhancing immunity. Conjugate vaccines induce antibody formation in people not responsive to polysaccharide alone, induce higher levels of antibody, and show a booster response on repeated injection.

Univalent antigen-binding fragments composed of one entire IMMUNOGLOBULIN LIGHT CHAIN and the amino terminal end of one of the IMMUNOGLOBULIN HEAVY CHAINS from the hinge region, linked to each other by disulfide bonds. Fab contains the IMMUNOGLOBULIN VARIABLE REGIONS, which are part of the antigen-binding site, and the first IMMUNOGLOBULIN CONSTANT REGIONS. This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.

A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally being called a macroglobulin.

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 which retain the crystal violet stain when treated by Gram's method.

Immunoglobulins induced by antigens specific for tumors other than the normally occurring HISTOCOMPATIBILITY ANTIGENS.

Bacterial infections of the leptomeninges and subarachnoid space, frequently involving the cerebral cortex, cranial nerves, cerebral blood vessels, spinal cord, and nerve roots.

Established cell cultures that have the potential to propagate indefinitely.

A group of broad-spectrum antibiotics first isolated from the Mediterranean fungus ACREMONIUM. They contain the beta-lactam moiety thia-azabicyclo-octenecarboxylic acid also called 7-aminocephalosporanic acid.

The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.

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.

Inflammation of the lung parenchyma that is caused by bacterial infections.

Vaccines or candidate vaccines used to prevent STREPTOCOCCAL INFECTIONS.

The processes triggered by interactions of ANTIBODIES with their ANTIGENS.

A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.

Infections with bacteria of the genus CHLAMYDOPHILA.

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.

Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.

Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.

Transfer of immunity from immunized to non-immune host by administration of serum antibodies, or transplantation of lymphocytes (ADOPTIVE TRANSFER).

Any infection acquired in the community, that is, contrasted with those acquired in a health care facility (CROSS INFECTION). An infection would be classified as community-acquired if the patient had not recently been in a health care facility or been in contact with someone who had been recently in a health care facility.

Proteins that bind to particles and cells to increase susceptibility to PHAGOCYTOSIS, especially ANTIBODIES bound to EPITOPES that attach to FC RECEPTORS. COMPLEMENT C3B may also participate.

'Azā compounds' are a class of organic molecules containing at least one nitrogen atom in a five-membered ring, often found in naturally occurring substances and pharmaceuticals, with the name derived from the Arabic word "azZa" meaning 'strong' referring to the ring's aromatic stability.

A species of thermophilic, gram-positive bacteria found in MILK and milk products.

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.

Proteins prepared by recombinant DNA technology.

Antibodies from non-human species whose protein sequences have been modified to make them nearly identical with human antibodies. If the constant region and part of the variable region are replaced, they are called humanized. If only the constant region is modified they are called chimeric. INN names for humanized antibodies end in -zumab.

The ability of bacteria to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).

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.

Enzymes that catalyze the transfer of hexose groups. EC 2.4.1.-.

Proteins, glycoprotein, or lipoprotein moieties on surfaces of tumor cells that are usually identified by monoclonal antibodies. Many of these are of either embryonic or viral origin.

Suspensions of attenuated or killed bacteria administered for the prevention or treatment of infectious bacterial disease.

A bacterial DNA topoisomerase II that catalyzes ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. Gyrase binds to DNA as a heterotetramer consisting of two A and two B subunits. In the presence of ATP, gyrase is able to convert the relaxed circular DNA duplex into a superhelix. In the absence of ATP, supercoiled DNA is relaxed by DNA gyrase.

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.

Transport proteins that carry specific substances in the blood or across cell membranes.

A species of gram-positive, coccoid bacteria commonly isolated from clinical specimens and the human intestinal tract. Most strains are nonhemolytic.

Acyltransferases that use AMINO ACYL TRNA as the amino acid donor in formation of a peptide bond. There are ribosomal and non-ribosomal peptidyltransferases.

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.

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.

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.

Gel electrophoresis in which the direction of the electric field is changed periodically. This technique is similar to other electrophoretic methods normally used to separate double-stranded DNA molecules ranging in size up to tens of thousands of base-pairs. However, by alternating the electric field direction one is able to separate DNA molecules up to several million base-pairs in length.

Enzyme which catalyzes the peptide cross-linking of nascent CELL WALL; PEPTIDOGLYCAN.

Infections with bacteria of the genus HAEMOPHILUS.

The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes IMMUNE COMPLEX DISEASES.

Antibodies reactive with HIV ANTIGENS.

Pathological processes involving the NASOPHARYNX.

Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.

A group of derivatives of naphthyridine carboxylic acid, quinoline carboxylic acid, or NALIDIXIC ACID.

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).

A broad-spectrum antimicrobial carboxyfluoroquinoline.

Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory IgA (IMMUNOGLOBULIN A, SECRETORY) is the main immunoglobulin in secretions.

Techniques used in studying bacteria.

Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow).

Serum that contains antibodies. It is obtained from an animal that has been immunized either by ANTIGEN injection or infection with microorganisms containing the antigen.

The body fluid that circulates in the vascular system (BLOOD VESSELS). Whole blood includes PLASMA and BLOOD CELLS.

Histochemical localization of immunoreactive substances using labeled antibodies as reagents.

A technique using antibodies for identifying or quantifying a substance. Usually the substance being studied serves as antigen both in antibody production and in measurement of antibody by the test substance.

A semi-synthetic macrolide antibiotic structurally related to ERYTHROMYCIN. It has been used in the treatment of Mycobacterium avium intracellulare infections, toxoplasmosis, and cryptosporidiosis.

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.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.

Facilities which provide care for pre-school and school-age children.

The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).

The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.

Elements of limited time intervals, contributing to particular results or situations.

Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.

The rate dynamics in chemical or physical systems.

Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)

Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.

Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.

Infections by bacteria, general or unspecified.

Non-susceptibility of an organism to the action of the cephalosporins.

Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.

Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.

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.

Techniques for removal by adsorption and subsequent elution of a specific antibody or antigen using an immunosorbent containing the homologous antigen or antibody.

Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.

The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.

Rupture of bacterial cells due to mechanical force, chemical action, or the lytic growth of BACTERIOPHAGES.

Cyclic AMIDES formed from aminocarboxylic acids by the elimination of water. Lactims are the enol forms of lactams.

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.

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.

Proteins isolated from the outer membrane of Gram-negative bacteria.

Nonsusceptibility of bacteria to the action of CHLORAMPHENICOL, a potent inhibitor of protein synthesis in the 50S ribosomal subunit where amino acids are added to nascent bacterial polypeptides.

Broad-spectrum cephalosporin antibiotic resistant to beta-lactamase. It has been proposed for infections with gram-negative and gram-positive organisms, GONORRHEA, and HAEMOPHILUS.

A broad-spectrum semisynthetic antibiotic similar to AMPICILLIN except that its resistance to gastric acid permits higher serum levels with oral administration.

Substances that are recognized by the immune system and induce an immune reaction.

Inflammation of the coverings of the brain and/or spinal cord, which consist of the PIA MATER; ARACHNOID; and DURA MATER. Infections (viral, bacterial, and fungal) are the most common causes of this condition, but subarachnoid hemorrhage (HEMORRHAGES, SUBARACHNOID), chemical irritation (chemical MENINGITIS), granulomatous conditions, neoplastic conditions (CARCINOMATOUS MENINGITIS), and other inflammatory conditions may produce this syndrome. (From Joynt, Clinical Neurology, 1994, Ch24, p6)

The space and structures directly internal to the TYMPANIC MEMBRANE and external to the inner ear (LABYRINTH). Its major components include the AUDITORY OSSICLES and the EUSTACHIAN TUBE that connects the cavity of middle ear (tympanic cavity) to the upper part of the throat.

Substances elaborated by viruses that have antigenic activity.

Lymphocytes responsible for cell-mediated immunity. Two types have been identified - cytotoxic (T-LYMPHOCYTES, CYTOTOXIC) and helper T-lymphocytes (T-LYMPHOCYTES, HELPER-INDUCER). They are formed when lymphocytes circulate through the THYMUS GLAND and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen.

Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.

The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.

Inflammation of the throat (PHARYNX).

Pyruvate oxidase is an enzyme complex located within the mitochondrial matrix that catalyzes the oxidative decarboxylation of pyruvate into acetyl-CoA, thereby linking glycolysis to the citric acid cycle and playing a crucial role in cellular energy production.

Autoantibodies directed against various nuclear antigens including DNA, RNA, histones, acidic nuclear proteins, or complexes of these molecular elements. Antinuclear antibodies are found in systemic autoimmune diseases including systemic lupus erythematosus, Sjogren's syndrome, scleroderma, polymyositis, and mixed connective tissue disease.

A penicillin derivative commonly used in the form of its sodium or potassium salts in the treatment of a variety of infections. It is effective against most gram-positive bacteria and against gram-negative cocci. It has also been used as an experimental convulsant because of its actions on GAMMA-AMINOBUTYRIC ACID mediated synaptic transmission.

Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.

Immunoglobulins produced in a response to FUNGAL ANTIGENS.

Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation.

Four-membered cyclic AMIDES, best known for the PENICILLINS based on a bicyclo-thiazolidine, as well as the CEPHALOSPORINS based on a bicyclo-thiazine, and including monocyclic MONOBACTAMS. The BETA-LACTAMASES hydrolyze the beta lactam ring, accounting for BETA-LACTAM RESISTANCE of infective bacteria.

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.

Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.

Inbred CBA mice are a strain of laboratory mice that have been selectively bred to be genetically identical and uniform, which makes them useful for scientific research, particularly in the areas of immunology and cancer.

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

Bacterial polysaccharides that are rich in phosphodiester linkages. They are the major components of the cell walls and membranes of many bacteria.

Tests that are dependent on the clumping of cells, microorganisms, or particles when mixed with specific antiserum. (From Stedman, 26th ed)

Techniques used to demonstrate or measure an immune response, and to identify or measure antigens using antibodies.

Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.

An antibacterial agent that is a semisynthetic analog of LINCOMYCIN.

Direct nucleotide sequencing of gene fragments from multiple housekeeping genes for the purpose of phylogenetic analysis, organism identification, and typing of species, strain, serovar, or other distinguishable phylogenetic level.

Calcium and magnesium salts used therapeutically in hepatobiliary dysfunction.

The clear, viscous fluid secreted by the SALIVARY GLANDS and mucous glands of the mouth. It contains MUCINS, water, organic salts, and ptylin.

Differentiation antigens residing on mammalian leukocytes. CD stands for cluster of differentiation, which refers to groups of monoclonal antibodies that show similar reactivity with certain subpopulations of antigens of a particular lineage or differentiation stage. The subpopulations of antigens are also known by the same CD designation.

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)

Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.