Readers may find it useful to go through the following definitions, or at least indications of their meanings.
A
Abscess:
A localized collection of pus.
Acid fast:
Resistant to decolorization by acid after staining with hot carbol fuchsin and hence retaining a red color when stained by Ziehl-Neelsen method.
Accessory:
Something added which helps.
Active immunity:
Dependent upon stimulation of person's own immunological mechanisms.
Active:
To make something work.
Adenine:
A purine constituent of nucleic acid.
Adenosine triphosphate (ATP):
Compound in which energy is stored in high energy phosphate bonds; its components are the purine adenine, D-ribose and three phosphoric acid groups.
Adjuvant:
Insoluble materials which act to keep antigens in tissues for longer period, thus cause a longer stimulation of antibody production.
Aerobe:
An organism which requires oxygen to live and reproduce.
Agglutinate:
To join together to form clump.
Allele:
One of a group of genes which can occupy a given place on a pair of identical chromosomes.
Allergy:
An abnormal sensitive reaction.
Anaerobe:
A microorganism not requiring oxygen to live or reproduce.
Anamnestic reaction:
A rise of an existing antibody level in response to irrelevant stimulus.
Anhydrous:
Containing no water.
Anode:
A positive electrode.
Antagonism:
Impairment of the efficacy of drug in the presence of the other.
Antibiotic:
A substance used to kill microorganisms. It is a product of microorganism
Antibody:
A globulin produced in the body in response to the antigen or foreign bodies.
Antigen:
Any substance which can cause the production of antibodies.
Antiserum:
A serum containing antibodies against particular organism.
Antitoxin:
An antibody against particular toxin.
Asepsis:
Without infection.
Atmospheric pressure:
The pressure of air on earth.
Attenuated:
Reduced virulence but retaining antigenecity for host.
Atypical:
Unusual.
4Autoinfection:
Infection of oneself.
Automatic:
Doing something by itself.
B
Bacilli:
Stick-like or rod-like bacteria.
Bacteria:
Single celled organisms containing both RNA and DNA which reproduce by binary fission.
Bacteriology:
The study of bacteria.
Bacteremia:
Presence of bacteria in bloodstream.
Bacteriocide:
A chemical used to kill bacteria.
Balantidium coli:
A protozoan ciliate causative agent of balantidiasis, a type of dysentry.
Beaded:
Staining at intervals along the length of bacillus.
Binary fission:
Simple cell division by which the nucleus and cytoplasm divides into two.
Biologic oxidation:
Any chemical reaction occurring within a cell that results in the release of energy respiration.
Biologic oxygen demand (BOD):
A measurement of the amount of oxygen required for the microbial decomposition of the organic matter present in water.
Biopsy:
The removal of small piece of tissue during life for examination.
Bio-type:
A classification or a group of genetically similar organisms.
Bi-polar:
The staining of bacillus at both ends.
Blister:
A small swelling in the skin filled with serum.
Bovine:
Associated with cattle.
Booster dose:
Additional infection of antigen to maintain antibody production at its peak.
Brittle:
Easily broken.
Brownian movement:
Passive to and fro movement of bacteria suspended in a fluid, due to irregular bombardment of molecules in fluid.
Budding:
An asexual form of reproduction of unicellular organisms, e.g. yeast cells.
Buffer:
A solution, the reaction of which is not easily altered by adding an acid or alkali.
C
Candling:
Inspection of an unbroken egg by holding it in front of bright light source to know whether embryo is alive or dead.
Capsid:
The protein coat surrounding the genome of virus.
Capsomere:
One of the units of which virus capsid is composed.
Capsule:
A coating outside cell walls of some bacteria and fungi.
Carrier:
One who is harboring but not currently suffering any ill-effect from pathogenic organism.
Cathode:
A negative electrode.
Cell:
A microscopic mass of protoplasm containing nucleus.
Cell line:
An in vitro culture of cells of known origin.
Cellulitis:
The result of a spreading infection of pyogenic bacteria in the subcutaneous tissues.
Characteristic:
A quality which distinguishes something, i.e. typical.
Chemotherapeutic agent:
A synthetic chemical suitable for systemic administration and effective in treatment of microbial infections.
Chitin:
Polysaccharide containing glucosamine, characteristic of cell walls of some fungi and also found in insects.
Chromatin:
Darkly staining nuclear material.
5Chromosomes:
Thread-like structure in the cell nucleus which contains genes carrying inherited characteristics.
Chronic:
Slowly developing.
Clone:
Cell derived from single cell.
Clinical disease:
The ways by which a disease shows itself in a patient.
Clue cells:
These are epithelial cells covered with large clumps of coccobacilli. They are good markers of infection.
Coccus:
A rounded or ovoid bacterium.
Colony:
A number of organisms living or multiplying together on culture media and they result from multiplication of a single organism.
Commensal:
Deriving nourishment from a host without causing any harm or benefit to host.
Complement:
A group of substances present in fresh serum and necessary for completion of some processes like lysis that result from anti-antibody interactions.
Control:
A check.
Constitutive
Produced under all circumstan-
enzyme:
ces, not dependent upon the presence of appropriate substrate.
Conjugation:
Exchange of genetic material between bacteria.
Culture:
The growth and multiplication of microorganism.
Culture media:
The material used in a culture to nourish the growth of microorganism.
Cytopathic effect:
Degenerative changes occurring in tissue culture cells as a result of microorganism infection.
Cytoplasmic streaming:
Continuous movement of cytoplasm within the cell which results in constant distribution of intracellular contents. It provides amoebic motility to some types of cells.
D
Darting:
A fast jerky movement.
Decolorize:
To remove color.
Deaminase:
An enzyme which catalyzes the removal of an amino group from a molecule with liberation of ammonia, the process is called deamination.
Delicate:
Fragile, which can be damaged easily.
Deposit:
The sediment at the bottom of tube.
Desiccation:
Drying or removal of water.
Detergent:
A surface active agent used in cleaning.
Diplococci:
Cocci which occur in pairs.
Disinfectant:
A substance of chemical nature used for destroying pathogenic microorganisms.
Distorted:
Altered or changed.
E
Effective:
Producing a result.
Electrolyte:
A chemical which helps to keep correct water balance between the fluid in the cell and that which surrounds it.
Elementary bodies:
Single chlamydiae particle visible by ordinary microscope after staining.
Embed:
To penetrate into tissue.
Emergency:
A serious situation requiring immediate attention.
Encapsulate:
To surround with a capsule.
Endemic:
A disease constantly present in an area.
Endogenous:
Originated by organisms or factors already present in the patient's body before onset of disease.
6Endotoxin:
A toxic component of microorganism (Gram negative), largely dependent on the death or disruption of the organism for its release.
Enriched medium:
A culture medium to which an extra nourishing substance is added.
Enrichment medium:
A liquid medium used to encourage preliminary growth of an organism so as to enhance the chances of growing it on subsequent plate culture.
Enzyme:
A chemical produced by living organism to help some particular reaction.
Epidemic:
A disease that temporarily has a high frequency in a given community.
Eradicate:
To get rid of.
Excision repair:
An enzyme system which can repair DNA by the elimination of ultraviolet light induced thymine dimers.
Exogenous:
Originated by organisms or factors from outside the patient's body.
Exotoxin:
A toxin released by living microorganisms into the surrounding medium or tissues.
Exudate:
A fluid, often from formed elements of blood, discharged from tissue to a surface or cavity.
F
Factor:
A substance with a special purpose, e.g. blood clotting factor.
Facultative:
Able to behave in a specified way, with the implication that is not, however, the usual behaviour.
Fermentation:
The slow decomposition, for example by microorganisms, of organic material such as the decomposition of a sugar solution by yeast to form alcohol.
Filament:
A fine thread-like structure.
Fimbria:
Hair-like protrusion from bacterial cells.
Flagellum:
Whip-like organ of motion.
Flocculant:
A mass of cells floating or settled to the bottom in a liquid medium.
Flocculation:
Precipitation in small cloudy mass.
Fluctuation test:
It is to determine the development of mutants in culture. The test is based on the concept that mutation is a completely random event, and spontaneous mutation would result in the number of mutants in a series of identical cultures.
Fluorosis:
Mottling of tooth enamel due to excessive amount of fluoride in water.
Fomites:
Objects contaminated with pathogenic microorganisms.
Fragment:
A piece broken off.
Fungus:
A simple unicellular or multicellular structure which reproduces by forming spores.
Fusiform:
Spindle shaped.
G
Gel:
To become solid, to set.
Gene:
A unit of inheritance found on chromosomes.
Genetic:
The study of inheritance.
Genome:
The total genetic material of an organism.
Genotype:
The inherited characters of a particular individual.
Genus:
A group of closely related species of plant, animal or microorganism.
Globulin:
A plasma protein divided into the alpha, beta and gamma fraction.
7Gram negative:
Staining red by Gram's method.
Gram positive:
Staining violet by Gram's method.
Growth factor:
An ingredient of which at least small amount must be present in a culture medium so that it supports the growth of given organism.
Granules:
Small grains or particles, e.g. metachromatic granules of diphtheria bacilli.
H
Halophilic:
Salt loving.
Hapten:
A substance which acts as an antigenic stimulus only when combined with protein but capable of reacting with resultant antibody in uncombined state even.
Hemolysis:
The destruction of red cells with the release of hemoglobulin.
Hereditary:
Transmitted from one generation to the other.
Hetero:
Different.
Heterologous:
Related to different kind of organism.
Hfr strain:
A high frequency mating strain.
Homologous:
Related to same kind of organism.
Host:
The organism from which a parasite takes its nourishment.
Hypertonic:
A condition in which the fluid surrounding a cell is more concentrated than that within it.
Hypotonic:
A condition in which the fluid surrounding a cell is less concentrated than that within it.
I
Identical:
Exactly same.
Immune:
Protected from disease by the presence of antibodies.
Immunoglobulin:
Globulins which act as antibodies.
Inactive:
The heating of serum at 56°C to destroy its complement and inhibitory factors.
Inclusion:
Something which is enclosed.
Incubate:
To keep at the same temperature for a given length of time.
Infection:
The entry and multiplication of pathogenic organisms within the body.
Inoculate:
To introduce a living organism into a culture medium.
Intra:
Inside.
In vitro:
In laboratory apparatus.
In vivo:
In a living animal or human being.
L
L-form:
Cell wall deficient mutant.
Ligases:
Enzymes that catalyze the linking together of two molecules.
Locus:
The definite place of a gene on a chromosome.
Lyophilization:
Combined freezing and desiccation (freeze drying).
Lysis:
Disruption.
Lysogenic conversion:
Alteration of the property of bacterium as a result of lysogeny.
Lysogeny:
A temporary stable relationship between bacteriophage and its bacterial host, in which the phage is reproduced in step with the bacterium and, thus, handed on to succeeding generation of bacteria.
M
Macrophage:
A large mononuclear phagocytic cell.
Medium:
A nutrient substance used to grow microorganisms.
8Metabolism:
The process of building up chemical compounds in the body and their breaking down during activity.
Microaerophile:
An organism which grows best in subconcentration of oxygen.
Misense mutation:
A change in cell's DNA with the effect that a wrong amino acid has been put into essential protein.
Molecule:
The smallest part of an element or compound which can exist in normal way.
Monolayer:
A sheet of tissue culture cells one cell thick.
Morphology:
A study of the form of cells and organisms.
Motile:
Capable of movement.
Moult:
The shedding of skin.
Mutation:
An alteration in genetic material.
N
Neutral:
Neither acidic or alkaline with pH of 7.0.
Nodule:
A small rounded swelling.
Normal:
Usual or ordinary.
Normal solution:
A solution in which the equivalent weight in grams of a chemical is dissolved in one litre of solution.
Nucleoid:
Genome.
Nucleocap:
The genome and capsid.
Nucleus:
An essential part of the living cell, containing the chromosomes and controlling cell activity.
Nutrition:
Food.
O
Obligatory anaerobe:
An organism which cannot live in oxygen.
Occult:
Hidden.
Opaque:
Not allowing light to pass.
Optimum:
The most suitable.
Oxidation:
Combination with oxygen.
P
Pandemic:
World-wide epidemic.
Parasite:
An organism which takes its food from another organism without giving anything in return.
Passage:
Administration of microorganism to a host and its subsequent recovery from the host. This way pathogenicity of organism is modified.
Passive immunity:
Dependent upon injection of readymade antibodies and not upon the subject's own immunological mechanisms.
Pathogen:
An organism which can cause disease.
Petri dish:
A shallow circular flat bottomed glass or plastic dish used as a container for solid media.
Phage type:
The identity of a bacterial strain as indicated by its sensitivity or resistance to the lytic action of bacteriophages.
pH:
The symbol that indicates the acidity or alkalinity of a solution. pH less than 7 is acid and more than 7 is alkali.
Phagocyte:
A cell which ingests microorganisms.
Phenotype:
The expression of genotype.
Pigment:
A coloring substance.
Pilus:
Fimbria.
Plasmid:
An extrachromosomal portion of genetic material.
Polymerase:
General name of enzymes concerned with synthesis of nucleic acid.
Prophage:
Bacteriophage in a lysogenic relationship with its host.
Prophylactic:
A medicine to prevent disease.
Prozone:
The occurrence of an antigen-antibody reaction only when serum is adequately diluted but 9not when it is used at higher concentration.
Protoplast:
A bacterium deprived of its cell wall.
Puerperal fever:
Acute infection following child birth due to introduction of infectious agent into the uterus.
Purulent:
Containing pus.
Pus:
A thick yellowish green fluid containing phagocytic cells collecting in tissues infected with pyogenic bacteria.
Pyogenic:
Pus forming.
R
Rack:
A stand for holding tubes.
Rash:
A skin reaction, usually seen as small reddened or raised area.
Reaction:
An action which takes place in response to something.
Reagin:
Antibodies associated with certain types of hypersensitivity reactions. It may be contained in serum causing Wassermann reaction and related reactions.
Recombinant:
A cell or clone of cells resulting from conjugation.
Reduction:
The removal of oxygen from a chemical compound.
Replication:
Virus reproduction.
Reticuloendothelial system:
The system of phagocytic cells in the body.
Retraction:
Shrinking.
Ribonucleo protein:
Material in the cytoplasm and nucleus of cell.
Rodent:
A gnawing animal, e.g. rat, mouse.
Room temperature:
Usually 18 to 20°C.
Routine:
Carried out regularly.
S
Sanitize:
To reduce microbial number to safe levels.
Saprophytic:
Living on dead organic matter.
Saturated solution:
A solution which has dissolved as much as it can of a substance.
Satellitism:
Enhancement of bacterial growth on a solid medium around a source of growth factor.
Selective medium:
A solid culture medium on which all but the desired organisms are wholly or largely inhibited.
Septicemia:
Presence and multiplication of bacteria in blood stream resulting severe disease.
Serology:
The study of serum especially antibody contents.
Serotype:
Antigenic type.
Specific antibody:
An antibody which react with one particular antigen only.
Spheroplast:
Similar to protoplast with the difference that cell wall damage is partial and reversible.
Spirochete:
Genera of spiral bacteria.
Sterilization:
The process of killing all living microorganisms.
Symbiotic:
Living in mutually with the host.
T
Technique:
The method by which something is done.
Temperate phage:
A phage capable of a lysogenic relationship with its bacterial host.
Thermostat:
An instrument to control the temperature.
Tissue:
A group of similar cells.
Titer:
The highest dilution of antibody in a serum which will react with its specific antigen.
Tolerogen:
An antigen that induces tolerance.
Toxoid:
Toxin rendered harmless but retaining antigenicity.
10Transduction:
Transfer of genetic material from bacterial strain to another by means of bacteriophage.
Transformation:
Acquisition of genetic characters of one bacterial strain by a related strain grown in presence of DNA from the first strain.
Transport medium:
A medium which increases the chances of survival of microorganism during transportation from patient to laboratory.
Turbid:
Cloudy.
Typical:
Showing usual features.
U
Undulating:
Up and down, i.e. wavy.
Unicellular:
Single celled.
Unstable:
Easily changed.
Urticaria:
A skin rash caused by allergy.
V
Vaccinate:
To introduce into the body killed or mildly pathogenic organisms to produce resistance against disease.
Vaccine:
Material used in vaccination.
Variation:
A change from the usual.
Vector:
An insect which carries microorganism or parasite and is capable of transmitting this.
Viable:
Able to live.
Vibrio:
A comma shaped microorganism.
Viremia:
Presence of viruses in the bloodstream.
Virion:
A virus particle.
Virulent:
Harmful.
W
Working solution:
A solution used in a test, made up from concentrated stock solution.
Y
Yeast:
A unicellular fungus.
Z
Zygote:
The cell formed by the fertilization of a female cell by a male cell.