- Glossary of Microbiology
- History and Scope
- Morphology of Bacteria
- Nutritional Requirements of Bacteria
- Media for Bacterial Growth
- Classification and Identification of Bacteria
- Sterilization and Disinfection
- Infection
- Antimicrobial Therapy
- Bacterial Genetics
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 carbolfuchsin 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 reaction 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 antigenicity for host.
Atypical
Unusual.
Auto-infection
Infection of oneself.
Automatic
Doing something by itself.
B
Bacilli
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.
Bactericide
A chemical used to kill bacteria.
Balantidium coli
A protozoan ciliate causative agent of balantidiasis, a type of dysentery.
Beaded
Staining at intervals along the length of Bacillus.
Binary
Simple cell division by which the fission 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
A measurement of the amount of oxygen required for the microbial decomposition of the organic matter
(BOD)
present in water.
Biopsy
The removal of small piece of tissue during life for examination.
Biotype
A classification or a group of genetically similar organisms.
Bipolar
The staining of Bacillus at both ends.
Blepharoplast
Basal body structure in hemoflagellates from which axoneme arises.
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 of movement 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.
Chromosomes
Thread-like structure in the cell nucleus which contains genes carrying inherited characteristics.
Chronic
Slowly developing.
Clone
Cell derived from single cell.
Clinical
The ways by which a disease shows disease 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.5
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 enzyme
Produced under all circumstances, 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.
Endotoxin
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 behavior.
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.
Gramnegative
Staining red by Gram's method.
Grampositive
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
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.
Metabolism
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.
Missense 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 nor 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 liter of solution.
Nucleoid
Genome.
Nucleocapsid
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
Worldwide 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.8
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 not 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.
Ribonucleoprotein
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
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 including spores.
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.
Transduction
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.