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61 Cards in this Set
- Front
- Back
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Transport medium
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a medium for transporting clinical specimens to the laboratory for examination, and able to keep the organism for 48 hours
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Pathogenicity
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the condition or quality of being pathogenic, or the ability of the microbe to cause disease in the host
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Virulence
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the objective, quantitative measurement of the pathogenicity of an agent. For example the virulence of a certain population can be expressed by LD50 titer.
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Heterophil antigens
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an antigen which is found on a variety of different, phylogenetically unrelated species.
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Exotoxins
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A specific, soluble, antigenic, usually heat labile, injurious substance produced by certain gram-positive or gram-negative bacteria. It is formed within the cell, but released into the environment where it is active, even in extremely small amounts. The host is damaged by their specific pharmacological effect, for example they can be cytolytic ensymes. Most exotoxins are protein in nature (MW 70,000 to 900,000) and can have the toxic portion of the molecule destroyed by heat, prolonged storage or chemicals. The non-toxic but antigenic form is a toxoid, which can be used for vaccination. Syn: ectotoxin, extracellular toxin.
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Endotoxins
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The complex phospholipid-polysaccharide macromolecules that form an intergral part of the cell wall of a variety strains of gram-negative bacteria. The lipid A portion of LPS is responsible for endotoxin activity. The toxins are relatively heat-stable, and less potent than the most exotoxins. They are also less specific and do not form toxoids. On injection, they may cause a state of shock by stimulating the production and the release of acute-phase cytokines.
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Active immunisation
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After giving live or killed infectious agent or their antigens, the host actively produces antibodies and the lympoid cells acquire the ability to respond to the antigens.
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Passive immunisation
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Giving ready made antibodies, during the incubation period or when the patient is already ill, so there’s no time to use active immunisation, or when we don’t have active vaccine for the certain disease.
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Agglutination-Antigen
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antibody reaction ends up in visible sedimentation of Ag-Ab complex. The antigens are cellular or the Ag is bound to a particle of cellular size. It is used for detecting antigens from specimens with known antibody or to detect antibodies with known antigens. E.g.: serotyping of E.coli isolates.
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Precipitation
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Antigen- antibody reaction ends up in visible sedimentation of Ag-Ab complex. The antigens are dissolved. E.g.: lues serology- precipitation in a “semi-solid” phase (agar gel): e.g. Elek-test
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Antibody titer
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the lowest concentration (the highest rate of dilution) of antibodies at which the given reaction still gives a visible result
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resident flora
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the bacterial population living normally in us (skin, mucosa, etc.)
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transient flora
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a bacterial population that is temporarily found at that place
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Vaccine
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Any preparation used for active immunological preventive treatment e.g. preparations of killed microbes of virulent strains, or living microbes of attenuated (variant or mutant) strains, or antigens of microbes
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Toxoid
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an exotoxin detoxicated by heat or formaldehyd, can provake an immune response, but not toxic. E.g.: vaccine for diphteria and tetanus
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Attenuation
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selecting mutant, not virulent strains of a microbe. These alive, but harmless microbes can provoke an immune response, so they can be used for vaccination E.g.: BCG vaccine contains attenuated Mycobacterium bovis.
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Agglutinin
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an antibody that causes clumping or agglutination of the bacteria or other cells which stimulated its formation
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Co-aggutination
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A passive agglutination test in which specific antibody is in vitro bounded to the surface of S. aureus cells. The bounded antibodies cause agglutination if the homolog antigen is added. The antibodies (or the antigens) can be bounded also to latex particles, then it is called latex agglutination .
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Precipitin
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an antibody that under suitable conditions crosslinks with its specific, soluble antigen and causes precipitation from solution.
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O antigen
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Somatic antigen of enteric gram-negative bacteria. External part of cell wall lipopolysaccharide.
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H antigen
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flagella, highly antigenic part of enteric gram-negative bacteria. So named because first identified in motile bacteria from a film (or in German Hauch) of spreading growth on agar medium.
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Capsule antigen
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the capsule of the bacteria is highly antigenic in most cases, in enteric bacteria it is called K antigen. E.g.: the specific polysaccharides of various types of pneumococci.
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Protective antigen
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antigen, which is responsible for generating protective immunity, so we can use it for vaccination.
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Bacteriolysis
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the dissolution of bacteria, e.g., by using a hypotonic solution or by specific antibody and complement, that destroy the bacterial membrane
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Epidemy
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infections occuring as part of an outbreak of infection- defined as a significant increase in the usual rate of that infection in the specified population. (epidemiology: study of the occurrence, distribution and determinants of health and disease in the population) E.g. Influenza A virus causes epidemy in every 2-3 year because of the new mutant strains caused by antigen drift.
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Endemy
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a disease which happens in a relatively low number, but continually in a community E.g. enteric fever is endemic in some of the developing countries.
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Pandemy
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worldwide epidemy, the infectious disease attacks the population of an extensive region, it usually appears on more than one continent. E.g. the seventh pandemy of cholera, which is still going on, caused by Vibrio cholerae El Tor biotype, began in Asia in 1961 and spread to Africa, Europe, Oceania, South and North America.
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Vector
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1. An invertebrate animal (e.g. tick, mite, mosquito, bloodsucking fly) capable of transmitting an infectious agent among vertebrates. 2. DNA that automatically replicates in a cell to which another DNA segment may be inserted and itself replicated as in cloning
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Antibiotic resistance
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the ability of a microorganism to survive and multiply in the presence of antibiotics. Usually carried on bacterial plasmids.
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Polyresistance
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A microorgamism showing resistance to many groups of antibiotics.
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Cross resistance
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when resistance to one antibiotic means resistance to a second with a similar mode of action as the first.
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Bactericidal effect
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the ability of a substance to kill bacteria.
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Bacteriostatic effect
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the ability of a substance to inhibit the growth of bacteria
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Selective toxicity
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an antibacterial agent kills only the bacteria, leaving the host unharmed (totally or relatively)
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Minimal Inhibitory Concentration (MIC)
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the lowest concentration of antibiotic sufficient to inhibit bacterial growth and proliferation when tested in vitro.
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Minimal Bactericidal Concentration (MBC)
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the lowest concentration of antibiotic that kills bacteria (different for different strains)
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Chemotherapeutic Index
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the ratio of the minimal effective dose (in Latin: dosis curativa minima) of a hemotherapeutic agent to the maximal tolerated dose (dosis tolerata maxima). CI=DTM/DCM, the higher is this ratio, is the safer to use the substance.
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Antibiogram
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A record of the resistance of microbes to various antibiotics, which is result of susceptibility testing (determination of the ability of an antibiotic to kill or inhibit the growth of bacteria)
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Aerobic bacteria
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A bacterium that uses oxygen, and is capable of living and surviving in the open air
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Obligate Anaerobic Bacteria
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An anaerobic bacterium that will grow only in the absence of free oxygen, and not able to survive in the presence of oxygen
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Facultative Anaerobic Bacteria
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an anaerobic bacterium, which grows in the presence of air, but can also survive under conditions of reduced oxygen.
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Microaerophilic Bacteria
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An aerobic bacterium that requires oxygen, but less than is present in the air, and grows best under modified atmospheric conditions.
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Differential Media
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a medium that will cause the colonies of a particular type of organism to have a distinctive appearance. E.g. EMB (Eosin Methylene Blue) medium is used to distinguish between lactose-fermenting (purple colonies) and non-fermenting (colourless colonies) gram-negative bacteria.
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Selective Media
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A culture medium containing ingredients that inhibit growth of any microorganism other beside the desired one. E.g. EMB is not only differential but also selective medium, because it inhibits the growth of gram-positive bacteria, only gramnegative bacteria will appear on that.
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Obligate Pathogenic Bacteria
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a bacterium that is pathological whenever present.
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Facultative Pathogenic Bacteria
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a bacterium that may causes illness, not in all cases, just under special circumstances (e.g. normal flora of our body, as E.coli)
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Ubiquitous Bacteria
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bacteria that lives in our environments.
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Autotrophic Bacteria
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a bacterium that produces food for itself from inorganic compounds.
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Heterotrophic Bacteria
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a bacterium that produces food for itself from organic compounds.
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Paratrophic Bacteria
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a bacterium that is obligate intracellular parasite, and is able live only in an eukaryote cell (therefore we are not able to cultivate them in vitro) E.g. rickettsiae
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Parasitism
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a relationship between the host and the microbe, when the presence of the microbe is harmful for the host
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LD50 Definition
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Lethal Dose 50% or Median Lethal Dose: the dose likely to cause death of 50% of the test animals The LD is dependent on the kind of the organism. (LD100:absolute lethal dose, is the dose that kills all of the test animals or bacteria)
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Zoonosis
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an infection or parasite shared in nature by humans and other animals that are normal or usual host, the disease of humans is acquired from an animal source.
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Bacterium Strain
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a population of bacteria originated from one colony maintained for a long time during laboratory condition with constant genetic properties.
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Bacterial Isolate
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a population of bacteria that belong to one species and was isolated at a certain time from a certain origin.
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Primary Immune Response
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the response of the immune system to a first encounter with an antigen, which leads to the condition of induced sensitivity. The primary immune response is detectable, as a rule, only after a lag period. IgM is the main immunoglobulin produced early in the primary immune response, followed by IgG, IgA or both. The serum antibody concentration continues to rise for several weeks and then declines, the IgM levels sooner than the IgG.
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Secondary Immune Response
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the immune response to a second encounter with an antigen. The secondary response is much faster than in case of the primary immune response, because of the persistence of antigen-sensitive memory-cells remaining from the first immune response. IgG is the predominant immunoglobulin in secondary responses, and its level tends to persist much longer than in the primary response.
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Sterilisation
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the total destruction of all microbes. That can be accomplished using physical, gas vapour or chemical sterilants.
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Parameters of Autoclaving and Circulating Hot Air Sterilization
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Hot Air: normal pressure 140 C for 3 hours / 160 C for 2 hours / 180 C for 1 hour; Autoclave: + 1 atm pressure 121 C for 30 min; Flash Autoclave: + 2 atm pressure 134 C for 3 min
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Disinfection
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treatment which reduces the number of potentially pathogenic microorganism in an environment (does not destroy all microbes)
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Ribotype
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the typing of bacteria, based on the 16s subunit of the ribosome.
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