This document defines various concepts and terminology used in microbiology. It provides definitions for over 50 terms, including types of microorganisms (such as aerobes, anaerobes, bacilli), microbial structures (such as flagella, capsule), microbial properties (such as acid-fast, pathogenic), host responses (such as antibody, immunity), and methods of controlling microbes (such as antiseptics, disinfectants, sterilization). The purpose is to help understand the meanings of terms commonly used in the study of microbiology.

1. TERMINOLOGY
BY MANOJ KUMARI

2. CONCEPTS AND TERMINOLOGY
USED IN MICROBIOLOGY
 INTRODUCTION:-
 This chapter helps in understanding the meaning of
terminology used in microbiology which makes the
study of microbiology easy.

3. A
 Acid-fast: A term applied to bacteria which retains a stain
even though treated with acid and alcohol.
 Acquired immunity: Any type of immunity which is not
inherited.
 Active immunity: The production of antibody by an
individual.
 Aerobe: An organism that grows in the presence of
oxygen.
 Anaerobe: An organism that grows in the absence of
oxygen.
 Antibody: A substance produced in an organism due to
the presence of an antigen and characterized by reacting
specifically with the antigen in some demonstrable way.

4.  Antigen: Substance which, when introduced, causes the body
to produce antibodies.
 Antiseptic: A chemical substance which prevents growth of
bacteria.
 Antiserum: Blood serum that contains antibodies.
 Antitoxin: An antibody capable of uniting with and neutralizing
a specific toxin.
 Aseptic technique: Precautionary measures taken to prevent
contamination.
 Attenuated: A weakening; a reduction in virulence.
 Asepsis: A condition without infection.
 Autoinfection: Infection of one part of body by bacteria derived
from some other part of the body.

5. B
 Bacillus (Plural-bacilli): Rod shaped bacterium.
 Bacteremia: A condition in which bacteria is present in
blood stream but do not multiply there.
 Bactericide (bactericidal): An agent which kills bacteria.
 Bacteriostatic: Inhibiting the growth of bacteria without
killing them.
C
 Carrier: One who harbours a pathogen without any
manifestations of infection.
 Capsule: An envelope or slime layer surrounding the cell
wall of certain microorganisms.
 Chemotherapy: The treatment of disease by the use of
chemicals.

6.  Communicable: Capable of being transmitted from one
person to another.
 Convalescent carrier: A carrier who harbours the
organisms of a disease during recovery from the disease.
 Commensal: Natural microflora (different groups of
microorganisms) present in host body without causing
disease or any harm.
 Culture: A growth of microorganisms on nutrient medium,
artificially or on living cells.

7. D
 Disinfectant: An agent which kills or destroys pathogenic
microorganisms.
 Disinfection: Is a process which kills or destroys
pathogenic microorganisms.
 Droplet infection: The transmission of infection via
minutes particles of sputum that have been disseminated
into air by sneezing, coughing, talking, etc.
 Deodorant: A substance that destroys unpleasant odour.
E
 Endemic: A disease prevalent in a particular area.
 Epidemic: A disease that attacks a large number of persons
in a community at the same time

8. F
 Fumigation: Exposure to the fumes of a gas that destroys
bacteria, vermin, etc. in a particular area e.g. O.T.
 Flagella (Single flagellum): Long hair like processes or
structures which by their lashing activity cause the
organisms to move. One or more flagella may be attached
to one or both ends of organism or completely around it.
 Fomites: Nonliving substances other than food that may
transmit infectious organisms, e.g. toys, pencils, etc.
G
 Germicide: An agent that destroys germs

9. H
 Helminth: A worm that commonly act as intestinal
parasite in humans.
I
 Immune system: A system that provides resistance to a
given infection.
 Immunity: Natural or acquired resistance to a disease
 Infection: Invasion of the body by pathogenic agent with
their subsequent multiplication and the production of
disease.
M
 Microscope: An instrument used to observe microbes.

10. N
 Nosocomial infections: Infections acquired from hospital.
O
 Opsonin: it is an antibody that renders microorganisms
susceptible to ingestion by phagocytes.
P
 Pandemic: A widespread epidemic disease, even of word wide
extend
 Passive carrier: a carrier who harbors the causative agent of
disease without having or had the disease.
 Passive immunity: Readymade antibodies are introduced in
host's body in emergencies and host's body plays a passive role
against infectious organisms.

11.  Pasteurization: The process of heating a liquid food or
beverage to a controlled temperature to enhance the quality and
destroy harmful microorganisms.
 Pathogenic: Capable of causing disease.
S
 Secondary infection: An infection which occurs during or
immediately after another infection.
 Septicemia: The presence and active multiplication of bacteria
in blood circulation.
 Sepsis: Poisoning by microbes or their products in host's body.
 Septic: Related to or caused by the presence of pathogenic
organisms or their poisonous products.
 Sporadic: The infection that occurs separately or apart from
others or its kind.

12. T
 Terminal disinfections: The complete disinfections of a
unit after the patient has left.
 Toxin: An poisonous agent of plant, microorganisms or
animal origin.
 Toxoid: Is a toxin that has been treated in such a manner
that its toxic properties are destroyed but the antigenic
properties remain same. For example. TT (Tetanus
Toxoid) and DT (DiphtheriaToxoid)

13. Thank you