MICROBIAL CONTROL Flashcards
____ Heat Sterilization
This is applicable for substances unaffected at a
temperature of ___ºC to 260ºC in the oven, at
an exposure time of 45 minutes.
DRY
148
Dry Heat Sterilization method kills ____, as well as _____ of microorganisms
spores, vegetative
forms
Dry Heat Sterilization method is ideal for sterilizing
glasswares,
metalwares, and anhydrous oils
Dry Heat Sterilization principle of sterilization involved is the
______ of microorganisms by heat.
oxidation
used to sterilize inoculating
instruments by the use of alcohol lamp or
burner
Direct flaming
burning materials to ashes
Incineration
This is more effective than dry heat method.
The principle of sterilization is the coagulation of
the cell protein of the microorganism.
Moist Heat Sterilization
It is the most effective method of moist heat
sterilization.
Autoclaving (steam under pressure)
Autoclaving (steam under pressure) can destroy the
sporeformers.
Autoclaving (steam under pressure) temperature used is ____ with a pressure
of ___ psi for 15-____ minutes exposure.
121ºC , 15 , 30
Temperature used is 100ºC
Kills many vegetative cells and viruses within 10
minutes.
Boiling
It uses a high temperature for a short time (__________) to destroy the pathogens
without altering the flavor of the food.
PASTEURIZATION 72ºC
for 15 seconds
are effective for vegetative forms of
microorganisms, but not for spores
Fractional Sterilization Method
It makes use of moist heat at 100 degrees
Celsius, using free flowing steam.
It is normally performed by 2 to 3 exposures,
alternated with intervals at room temperature or
incubator temperature.
Tyndallization
Fractional Sterilization Method:
Tyndallization
Inspissation
Filtration
Cold
Desiccation
Osmotic pressure
Radiation
It is a fractional method of sterilization
at 60 degrees Celsius in an oven, alternated
with intervals at room temperature or incubation
for 2 to 3 days
Inspissation
Inspissation
It is a fractional method of sterilization
at___ degrees Celsius in an oven, alternated
with intervals at room temperature or incubation
for 2 to 3 _____.
60
days
The passage of liquid or gas through a filter with
pores enough to retain microbes.
Filtration
Membrane filters composed of _______are commonly used to filter
out bacteria, viruses and even large proteins.
nitrocellulose or
cellulose acetate
The effectiveness of low temperatures depends
on the particular microorganisms and the
intensity of the application.
Microorganisms do not reproduce at ordinary
refrigerator temperatures (0º to 7ºC)
Cold
In the absence of water, microorganisms cannot
grow but can remain viable.
Desiccation
Viruses and endospores can resist
decolorization.
Microorganisms in high concentrations of salts
and sugars undergo
plasmolysis
Molds and yeasts are more capable of growing
in materials with____ moisture or ____ osmotic
pressure than bacteria are.
low, high
This is used to aid reduction of air borne
contamination produced by mercury vapor
lamps.
Ultraviolet radiation
Ultraviolet radiation
This is used to aid reduction of air borne
contamination produced by
mercury vapor
lamps
Ultraviolet radiation method has poor penetration
capability. Its effectiveness depends on:
a. length of time of exposure
b. intensity of radiation
c. susceptibility of the microorganism
This radiation method makes use of high
energy emitted from radioactive isotopes such
as cobalt 60 (gamma rays) or by cathode or
beta rays (mechanical acceleration of electrons
to high velocity and energy).
Ionization Radiation
Ionization Radiation
This radiation method makes use of high
energy emitted from ______ such
as cobalt 60 (gamma rays) or by cathode or
beta rays (mechanical acceleration of electrons
to high velocity and energy).
radioactive isotopes
are more reliable because there is
no mechanical breakdown, but it has a
disadvantage of rare source and cannot be shut
off immediately.
Gamma rays
provide higher and more
uniform dose outfit and can destroy organisms
by stopping its reproduction.
Accelerated electrons
Principles of Effective Disinfection
The presence of organic matter, degree of contact with microorganisms, and temperature should be considered.
Evaluating a Disinfectant
In the filter paper method, a disk of filter paper
is soaked with a chemical and placed on an
inoculated agar plate; a clear zone of inhibition
indicates effectiveness.
exert their action by injuring plasma
membranes, inactivating enzymes, and denaturing
proteins
Phenol and Phenolics
Common phenolics are
cresols and
hexachlorophene
damages plasma membranes of
vegetative cells.
Chlorhexidine
are used
alone or as components of inorganic or organic
solutions.
Halogens
Iodine is available as a _____ (in solution with
alcohol) or as an ______ (combined with an
organic molecule).
tincture
iodophor
The germicidal action of chlorine is based on
the formation of _______ when
chlorine is added to water.
hypochlorous acid
Chlorine is used as a disinfectant in gaseous
form (CI2) or in the form of a compound, such
as ______,______,_______.
calcium hypochlorite, sodium hypochlorite,
and chloramines
Alcohols exert their action by _______
proteins and dissolving lipids.
DENATURATION
Alcohols
In _____, they enhance the effectiveness of
other antimicrobial chemicals.
tinctures
Aqueous ethanol (___% TO ___%) and isopropanol
are used as disinfectants.
60% to 90%
are used as
germicidals.
Silver, mercury, copper, and zinc
Heavy Metals and Their Compounds exert their antimicrobial action through
oligodynamic action
decrease the tension
between molecules that lie on the surface of a
liquid; soaps and detergents are examples.
Surface-active agents
have limited germicidal action but assist
in the removal of microorganisms through
scrubbing.
Soaps
are used to clean dairy
equipment
Acid-anionic detergents
By disrupting plasma membranes, they allow
cytoplasmic constituents to leak out of the cell
Quaternary Ammonium Compounds
They are most effective against gram-positive
bacteria
Quaternary Ammonium Compounds
inhibit fungal metabolism
Sorbic acid, benzoic acid, and propionic acid
They are used as food preservatives.
Organic Acids and Derivatives: Sorbic acid, benzoic acid, and propionic acid
They are among the most effective chemical
disinfectants.
formaldehyde and
glutaraldehyde
is the gas most frequently used
for sterilization
Ethylene oxide
It penetrates most material s and kills all
microorganisms by protein denaturation
Gaseous Chemosterilizers
are used as antimicrobial
agents.
Ozone and peroxide
They exert their effect by oxidizing molecules
inside cells
Oxidizing Agents
