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Appendix C Glossary and Acronyms Active surveillance: Systematic and comprehensive solicitation of case data by designated staff supported for this purpose. Allele: Any one of a series of two or more different genes that may occupy the same position or locus on a specific chromosome. In humans and other diploid organisms, there are two alleles, one on each chromosome of a homologous pair. Aminoglycosides: Family of bactericidal antibiotics that block bacterial protein synthesis by binding to the small subunit of the bacterial ribosome; examples are streptomycin, kanamycin, neomycin, gentamicin, amikacin, and tobramycin. Ampicillin: Semisynthetic, acid-resistant, penicillinase-sensitive penicillin, effective against a broad range of gram-positive and gram-negative bacteria. Antibacterial: Drug that kills or inhibits the growth of bacteria. Antibiogram: Guide produced by a microbiology laboratory for physicians' use that profiles the susceptibility of commonly encountered bacteria to various antibiotics. Antibiotic: Class of substances that can kill or inhibit the growth of some groups of microorganisms. Used in this report to refer to chemicals active against bacteria. Originally antibiotics were derived from natural sources (e.g., penicillin from molds), but many currently used antibiotics are semisynthetic and modified with additions of man-made chemical components. See antimicrobials. Antibiotic resistance: Property of bacteria that confers the capacity to inactivate or exclude antibiotics, or a mechanism that blocks the inhibitory or killing effects of antibiotics.
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Antibiotic susceptibility: Opposite of resistance; applies to bacteria that are killed or inhibited by an antibiotic. Susceptibility to a particular antibiotic does not mean that the bacteria are susceptible to all antibiotics. Antibody: Any body or substance, soluble or cellular, that is evoked by the stimulus provided by the introduction of an antigen and that reacts specifically with the antigen in some demonstrable way. Antifungal: Antagonistic to fungi. Antigen: Chemical structure on or in a cell that is recognized by the immune system. The immune system produces antibodies that react with antigens. Antimicrobials: Class of substances that can destroy or inhibit the growth of bacteria. See antibiotics. Antiretroviral: Agent that is destructive to retroviruses. Antiviral: Opposing a virus, weakening or abolishing its action. Asymptomatic: Producing no symptoms. Avoparcin: Glycopeptide antibiotic derived from Streptomyces candidus; an antibacterial. Bacteremia: Pathologic state characterized by the presence of bacteria in the blood. Bacteria: Microscopic, single-celled organisms some of whose biochemical and structural features differ from those of animal and plant cells. Bactericidal: Term for agents that kill bacteria. Beta-lactam antibiotics: Most widely used class of antibiotics: comprised of penicillins, cephalosporins including ceftriaxone and ceftazidime, carbapenems, monobactams, and imipenem. ß-Lactam antibiotics act by inhibiting the synthesis of peptidoglycan, the major component of a bacterial cell wall. Biosynthesis: Formation of a chemical compound by enzymes, either in the organism (in vivo) or in fragments or extracts of cells (in vitro). Breakpoint: Concentration of antibiotic determined using antibiotic susceptibility tests that marks the division either between the resistant and intermediate response or between the intermediate and susceptible response. Broad-spectrum antibiotic: Antibiotic effective against a large number of bacterial species; generally describes antibiotics effective against both gram-positive and gram-negative bacteria. Campylobacter: Bacterial genus with a characteristic corkscrew-like motion, found in the oral cavity, intestinal tract, and reproductive organs of humans and animals. Some species may be pathogenic, causing enteritis and systemic disease in humans. Cell culture: Propagation of cells in a laboratory environment. Chromosome: As used in this report, the circular DNA that contains the genes for functioning of a bacterium.
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Clinical trial: As used in this report, research to establish the safety and efficacy of a drug such as an antibiotic. Colonization: Capacity of a bacterium to remain at a particular site and multiply there. Commensals: Bacteria that live on skin, in body orifices, or in the intestines; do not usually cause disease and may be beneficial to the host organism. Conjugation: Process involving cell-to-cell contact by which DNA is transferred from one bacterium to another. Conjunctiva: Delicate membrane that lines the eyelids and covers the exposed surface of the sclera. DNA (deoxyribonucleic acid): Substance of heredity: a nucleic acid found in the cell nucleus that carries the genetic information necessary for all cellular functions. DNA probe assay: New diagnostic method for identifying the presence of bacteria by using fragments of DNA or RNA (probes) that bind to target bacterial or resistance gene DNA or RNA sequences. Efficacy: As used in this report, the probability of benefit to individuals in a defined population from a medical technology applied for a given medical problem under defined conditions of use. Endemic: Present in a community or common among a group of people; said of a disease prevailing continually in a region. Enterococcus: Bacteria normally found in the intestinal and genitourinary tracts; some strains are pathogenic, and a few are resistant to all available antibiotics, including vancomycin. Epithelium: Purely cellular avascular layer covering all the free surfaces of a body, cutaneous, mucous, and serous, including the glands and other structures derived therefrom. Erwinia amylovora: Gram-negative, rod-shaped motile bacterium that is the causative agent of fire blight in pome fruits. Escherichia coli: Commensal bacterium that lives in the intestine and is sometimes a cause of opportunistic infections. Etiology: Science and study of the causes of diseases and their mode of operation. Eukaryote: Cell or organism with membrane-bound, structurally discrete nuclei and well-developed cell organelles; eukaryotes include all plants, animals, and fungi. Compare prokaryote. Expression: Functioning of a gene, generally measured by the amount of gene product (usually a protein or nucleic acid) made by the cell. See gene expression. Fastidious: In bacteriology, having complete nutritional requirements.
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Fingerprinting, DNA: Technique used in molecular biology for genome mapping, to identify specific DNA sequences. Fire blight: Destructive, highly infectious disease of pome fruits (i.e., apples, pears, etc.) that is caused by Erwinia amylovora and that produces a scorched or blackened appearance of the leaves and twigs, cankers on the trunk, or discoloration of flowers and fruits Flora: Populations of commensal bacteria normally present in the intestine, in body orifices, and on the skin. Footprinting: Method for detecting sites of interaction between regulatory or promoter proteins and DNA. Formulary: Listing of approved drugs for various medical indications, originally created as a cost-controlling measure but used more recently to guide usage of antibiotics based on information about resistance patterns. Fungus: Member of a class of relatively primitive organisms; includes mushrooms, yeasts, rusts, molds, and smuts. Gene: Unit of heredity; segment of the DNA molecule that carries directions for the structure of a given protein. Gene expression: Activity of a gene measured by the amount of gene product (usually a protein or nucleic acid) made by the cell. Genera: Plural of genus. Genetic recombination: Process by which separate lengths of DNA from different sources are chemically joined to produce new genetic combinations. Genome: Full set of genes in any organism. Genotype: Genetic constitution of an individual. Genus: Taxonomic category subordinate to tribe and superior to a species. Glycopeptides: Compounds made up of amino acids and sugars that may have antibacterial activity; vancomycin and teicoplanin are glycopeptide antibiotics. Gram-negative bacteria: Bacteria whose cell wall is composed of a thick layer of peptidologlycan covered by an outer membrane of lipoprotein and lipopolysaccharide. In the Gram-staining process these bacteria are decolorized. Gram-positive bacteria: Bacteria whose cell wall is composed of a thick layer of peptidologlycan with attached teichoic acids. In the Gram-staining process, these bacteria retain the stain. Haemophilus influenzae: Commensal bacterium commonly found in the upper respiratory tract and capable of causing infections such as otitis media, sinusitis, conjunctivitis, bronchopneumonia, and type b meningitis. Helicobacter pylori: Bacterium causing gastritis and peptic ulcer disease in humans. High throughput: Rapid, high-volume chemical screening for target compounds.
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Homology: Quality of being homologous and therefore corresponding in structure, position, or origin. Host: Animal or plant that harbors or nourishes another organism. Incidence: Frequency of new occurrences of disease within a defined time interval. Incidence rate is the number of new cases of a specified disease divided by the number of people in a population over a specified period of time, usually one year. Infection: Successful colonization on a site of the body by a microorganism capable of causing damage to the body. Inhibitor: Any substance that interferes with a chemical reaction, growth, or other biological activity. Intermediate resistance: Property of bacteria that can survive and grow in low concentrations, but not higher concentrations, of an antibiotic. Invasive: Pertaining to a bacterium (1) capable of penetrating the host's defenses; (2) capable of entering host cells or passing through mucosal surfaces and spreading in the body. In vitro tests: Techniques that use cells, tissues, or explants grown in a nutritive medium rather than living animals or human subjects. In vivo: Within the living body. Isolate: A pure culture of a microorganism. Macrolides: Family of bacteriostatic antibiotics that inhibit protein synthesis by binding to the large subunit of the bacterial ribosome; includes erythromycin, clindamycin, chloramphenicol (rarely used because of adverse side effects), and the new drugs clarithromycin and azithromycin. Mass spectrometry: Analytical method for measuring molecular mass and structure. Media: Plural of medium; substances used to culture bacteria. Methicillin-resistant Staphylococcus aureus: Strictly speaking, a bacterial strain resistant to methicillin. In practice, MRSAs are generally resistant to many antibiotics and some are resistant to all but vancomycin, so that the acronym is now generally used to mean ''multidrug-resistant S. aureus." MIC: See minimum inhibitory concentration. Microorganism: Minute, microscopic, or submicroscopic living organism; includes bacteria, fungi, and protozoa. Viruses are often included in this category, but they are incapable of growth and reproduction outside host cells, so that some experts insist they should not be classified as organisms. Minimum inhibitory concentration: Lowest concentration of antibiotic that prevents growth of a bacterium. Morbidity: Diseased condition or state. Mortality: Proportion of deaths to population or to a specific number of the population; death rate. MRSA: Methicillin-resistant S. aureus.
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MSSA: Methicillin-susceptible S. aureus. Multiple resistance or multiple drug resistance: Property of bacteria that are resistant to more than one antibiotic. Mutation: Genetic change that can occur either randomly or at an accelerated rate through exposure to radiation or certain chemicals (mutagens) and may lead to change in structure of the protein coded by the mutated gene. Mycobacterium: Gram-positive, aerobic, mostly slow-growing genus of bacteria containing many species, including the highly pathogenic organisms that cause tuberculosis. Narrow-spectrum antibiotic: Antibiotic effective against a limited number of microorganisms; often applied to one that is active against either gram-positive or gram-negative bacteria. Natural selection: Process by which ancestral species of animals and plants evolve into new species. Nosocomial infection: Infection acquired during hospitalization that is neither present nor incubating at the time of hospital admission (unless related to prior hospitalization) and may not become clinically manifest until discharge from the hospital. Notifiable disease: Disease physicians are required to report to state health departments. Nucleotide: Basic unit of nucleic acid that makes up DNA (which carries genetic information) and RNA (which is involved in protein synthesis). Oligonucleotide: Polymer made up of a few (2-20) nucleotides. Organelle: Any of the membrane-bound, organized cytoplasmic structures of distinctive morphology and function that are present in all eukaryotic cells. Otitis media: Inflammation of the middle ear. Parenteral: Injected or for injection subcutaneously, intramuscularly, or intravenously. Passive surveillance: Collection of case data, based on voluntary compliance, from reporting physicians, other health care providers, and laboratories. Pathogen: Organism capable of causing disease. Pathogenicity: Capacity to cause disease. PCR: See polymerase chain reaction. Peptide: Small protein molecule. Phenotype: Entire physical, biochemical, and physiological makeup of an individual, which is determined both genetically and environmentally; as opposed to genotype. Plasmid: Circular piece of DNA not associated with the chromosome found in the cytoplasm and capable of replicating and segregating independently; many plasmids can be spread through bacterial populations by conjugation,
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and many antibiotic-resistance genes of clinical significance are carried by plasmids. Polymerase chain reaction: Laboratory procedure that produces millions of copies of DNA from one or a few molecules. Polymorphism: Quality or character of occurring in several different forms; presence of two or more distinct phenotypes in a population due to the expression of different alleles of a given gene. Prevalence: Total number of cases (new as well as previous cases) of a disease in a given population at a point in time. Proficiency testing: Assessment of laboratory competence. Prokaryote: Organism lacking cell organelles whose DNA is not enclosed within a membrane-bound, structurally discrete nucleus. Bacteria and blue-green algae are prokaryotes. Compare eukaryote. Prophylactic antibiotic therapy: Administration of antibiotics before evidence of infection, that is intended to ward off disease. Prospective: Concerned with or relating to the future; effective in the future. Protein: Any group of complex organic compounds that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur, and are widely distributed in plants and animals. Quinolones: Class of purely synthetic antibiotics that inhibit the replication of bacterial DNA; includes ciprofloxacin and fluoroquinolone. Reference laboratory: Facility undertaking specific scientific or technical activities usually as part of a network of national, regional, and international participating institutions. Replication: Process of duplicating or reproducing, for example, an exact copy of a polynucleotide strand of DNA or RNA. Resistance: See antibiotic resistance. RNA (ribonucleic acid): Substance found in cytoplasm and some nuclei, a nucleic acid associated with the control of cellular chemical activities. Selective pressure: As used in this report, selection of antibiotic-resistant bacteria through the use of antibiotics; susceptible bacteria are killed or inhibited, and resistant ones are selected. Sensitivity: In an analytical capacity, the smallest concentration of a substance that can be measured reliably by a particular analytic method. Sentinel laboratories: Reference laboratories. Shigella dysenteriae: Highly pathogenic species of Shigella that causes severe dysentery. Specificity: Diagnostically, the conditional probability that a person not having a disease will be correctly identified by a clinical test.
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Staphylococcus aureus: Normally commensal bacteria on the skin that can cause nosocomial infections when they penetrate body tissues and organs as a result of wounds and surgery. See MRSA. Streptococcus pneumoniae or "pneumococcus": Most common cause of bacterial infection in the United States. Surveillance systems: As used in this report, data collection and record keeping to track the emergence and spread of disease-causing organisms such as antibiotic-resistant bacteria. Susceptibility test: Any of a large number of tests used to determine whether bacteria are susceptible or resistant to an antibiotic. Synthetases: Term used in the trivial or recommended names of enzymes, particularly those of the lygase class. Systemic: Pertaining to or affecting the body as a whole; frequently applied to bloodstream infections. Target: Denoting a cell or organ that is selectively affected by a particular agent. Taxonomy: Systematic distinguishing, ordering, and naming of type groups within a subject field. Transformation: Uptake by a bacterium of DNA from a ruptured cell and incorporation of genes from this DNA into the bacterial chromosome. Transposon: Small DNA element that can move among various DNAs—chromosomes, plasmids, and bacteriophages; often carries genes specifying antibiotic resistance. Vancomycin: Widely used glycopeptide antibiotic, particularly important for treatment of infections caused by strains of S. aureus, some of which are resistant to all other antibiotics. Vancomycin-resistant enterococcus: Bacterial strain; some VREs are resistant to all commercially available antibiotics. Virulence: Measure of the degree and severity of pathogenicity of a disease-causing organism. Virus: Submicroscopic pieces of genetic material (RNA or DNA) enclosed in a protein coat that cause infectious disease; obligate parasites that can reproduce only in living cells. VRE: See vancomycin-resistant enterococcus. VRSA: Vancomycin-resistant S. aureus. Western blot: Technique used in molecular biology that fractionates and detects protein antigens of specific molecular weights.
Representative terms from entire chapter: