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Terms in Sterilization |
Terms in
Sterilization
Sterilization:
Sterilization is the process by which all
viable microorganisms including spores are killed or eliminated.
There are
mainly three types of sterilization procedures:
1. Physical - Heat and Radiation
2. Chemical
3. Filtration
Disinfection:
Disinfection is the destruction of vegetative
pathogens but not the endospores or viruses from a surface of inanimate or
inorganic objects.
Disinfectant:
Disinfectant is mainly a chemical agent used
to kill microbes or reduce growth of microorganisms from any inorganic objects.
Example: Ethylene oxide, alcohols,
formaldehydes.
Antisepsis:
It is the prevention of growth of
microorganisms on living tissues by inhibiting their growth and metabolic
activity.
Antiseptic:
Antiseptics kill or prevent microbes on
living tissue.
Example: iodine, boric acid, hydrogen
peroxide.
Aseptic
techniques:
These are the precautionary measures taken to
prevent contamination with microbes.
Radiation:
Radiation is the energy transmitted through
space in a variety of forms.
There are
two types of radiation -
Ionizing
radiation- gamma ray, X-ray
and
Non-Ionizing radiation - UV radiation.
Filtration:
Filtration is the way of passing a liquid
suspension or gas through a screen like material with small pores (0.22 to 0.45
micrometer) to retain microorganisms.
Filtration is used to sterilize heat
sensitive materials such as antibiotics, vaccines, culture media, heat labile drugs and
solutions for intravenous use and to prepare antisera.
Pasteurization:
It is a method of lowering microbial numbers
and reduction of pathogens by heating.
Pasteurization involves 72℃ for 15 seconds,
which is HTST (high temperature short time) and at 140℃ for 2 seconds, which is
UHT (ultra high temperature).
Bactericidal
agent:
Bactericidal agent kills bacteria and it is
most effective.
They kill the
Example.
Cephalosporins
Bacteriostatic
agent:
They only inhibit microbial growth but don't
kill microbes.
They are less effective.
Example. Chloramphenicol.
Lyophilization:
It is a method in which low temperature
decreases chemical reactions and other changes in proteins.
It is a very effective method and used for drug
preservation.
Tyndallization:
Tyndallization is introduced by John Tyndall.
It is the process of fractional sterilization
with free - flowing steam at 100℃ with a incubation period of 3 days.
Tyndallization is used for sterilize media,
chemical solutions and biological materials.
D-value
(Decimal reduction time):
D-value is the time in minutes at a fixed
temperature or the radiation doses needed to kill 90% of a population of
bacteria.
Z-value:
It is the increase in temperature needed to
reduce the D-value of an organism by 90%.
F-value:
It represents heat treatment at any temperature
as equal to that of a certain number of minutes at 121℃.
Thermal
Death time (TDT):
The minimal length of time required to kill
all bacteria in a liquid suspension at a fixed temperature.
Thermal
Death point (TDP):
It is the lowest temperature at which all the
microbes in a liquid suspension will be killed within ten minutes.
"Terms
in Sterilization"
Written By
Sadia
Akhtar
Student of
Department of Microbiology
Jagannath
University.
Email-
sadiabd810@yahoo.com
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