LESSON 2 - MICROBIAL CONTROL Flashcards
Ignatz Semmelweis
Develop microbial control practice for medical procedures
Sterilization
Process by which all living microorganisms including viable spores, are either
destroyed or removed from an article, body surface or medium.
Disinfection
Process that destroys or removes most if not all pathogenic organisms but not
bacterial spores.
Antiseptic
A chemical substance which oppose sepsis or putrefaction either by killing
microorganism or preventing their growth.
Sterile
Free of a living of every kind
Bacteriostatic
Having the property of inhibiting bacterial growth or multiplication
Bactericidal
Having the property of killing or destroying bacteria precipitates bacterial protein
(H2SO4, HCl)
Germicide/Disinfec
tant
A chemical substance used to kill infection producing microorganism on the
surface but too toxic to be applied directly on tissues
Septic
Characterized by the presence of pathogenic microbes in living tissue
Aseptic
Characterized by the absence of pathogenic microbes
Decimal Reduction
Time ( DRT/ D/D)
Time in minutes to reduce the bacterial population or spores by 90% at a specified
temperature.
Asepsis
Process where the chemical agents (called antiseptics) applied to body surfaces
(skin) will kill or inhibit the pathogenic microorganisms (and also commensals)
present on skin.
Decontamination
(or sanitization)-
Reduction of pathogenic microbial population to a level at which items are
considered as safe to handle without protective attire.
1.Sunlight
2.Drying
Method
Principle
Sunlight
Active microbicidal effect due to its content of
ultraviolet rays.
Drying
70-80% of the weight of the bacterial cell is
due to water. Drying, therefore has a
deleterious effect on many bacteria.
Dry heat
Kills the organisms by charring, denaturation
of bacterial protein, oxidative damage and
by the toxic effect of elevated levels of electrolytes.
Moist heat
Kills the microorganisms by denaturation
and coagulation of proteins.
Flaming
Items are held in the flame of a Bunsen burner either for
long time or short time.
Incineration
Used for the disposal of waste materials.
Principle
Thickening Through Evaporation
Definition
Sterilize high protein-containing media that cannot
withstand high temperature
Temperature
70-80 degree Celsius for 3 consecutive days
Instrument
Inspissator
METHODS
TEMPERATURE
BOILING WATER
(STEAM)
100
Autoclave (steam
under Pressure)
121.6
Pasteurization Batch
Method
63
Pasteurization Flash
Method
72
Oven (Dry Heat)
160-180
Definition
Direct application of flame in aseptic technique,
Flaming with a Bunsen Burner
(Flaming mouth of culture tubes or slides),
Instrument
Bunsen Burner
Principle
The heat is absorbed by the outside surface of
the item, then passes towards the center of the
MOA
Dry heat does most of the damage by
oxidizing molecules.
The essential cell constituents are destroyed and
the organism dies.
The temperature is maintained for almost an
hour to kill the most difficult of the resistant
spores.
Temperature
170°C (340°F) for 30 minutes,
160°C (320°F) for 60 minutes,
150°C (300°F) for 150 minutes or longer depending
on the volume.
Biological Indicator/
Quality Control
Bacillus subtilis var niger (Bacillus atrophaeus)
at 35-37 degree Celsius
Berkefield
Filter
Diatomaceous
Earth
Chamberland
Filer
Unglazed
Porcelain
Seitz
Compressed
Asbestos
Membrane
Filters
(Swinney)
Millipore 0.22
mm
Chemosterilizers
Chemical used to sterilize
Antimicrobial Agent- chemicals that kill microorganisms or prevent their growth
-cide (Latin CIDA= KILL)- kill organism
-static (Greek Statikos- causing to stand or stop)- do not kill but prevents
the growth
-
Carcinogenicity
Principle
The machine introduces steam into the sterilization
chamber, which is then exhausted
Definition
• Most commonly used for sterilization
• Alkylation of nucleic acids in the spore and
vegetative cells
Recommended
Concentration
450-700 mg of ethylene oxide per liter of chamber
space at 55-60 degree Celsius for 2 hours
Biological Indicator
Bacillus subtilis var globijii
Principle
Kills all vegetative organism but not all spores or viruses
Definition
• Used in surgical instruments, needles,
• hypodermic syringes, rubber stoppers
Effective Indication
100 Degree Celsius for 15-30 minutes (20 minutes)
MOA
Degree to Cellular DNA by producing Thymine Dimers
Definition
Used in surgical instruments, needles, hypodermic
syringes, rubber stoppers
Radiation
• Ultraviolet rays (10um to 400 um) in which
MOA
Partially sterilizing organic solutions by heat without
altering their chemical properties
Definition
• Used to sterilize milk, dairy products and
alcoholic beverages
3 Types
- Low-Temperature Holding (LTH)/ Batch Method
I.
ALCOHOL
II.
HALOGEN
Tincture
iodine solution (2% iodine) + alcohol (70% alcohol)
Antiseptics
Iodophor
• Combination of iodine and neutral polymer
MOA
Oxidative effects of hypochlorous acid, formed
when chlorideions are dissolved in water
Definition
Hypochlorite- liquid sodium hypochlorite
(household bleach) + Sodium calcium hypochlorite
Long Exposure required for sporicidal action
(not used as sterilant)
Others
Concentrated Bleach- Should not be used for
disinfection(Corrosive)
0.5-1% Sodium Hypochlorite- used as disinfection,
stable for 30 days)
1:10 dilution of 5.25%- Recommended by CDC for
cleaning up blood spill
MOA
Denatures enzymes and other essential bacterial
proteins
Inactivating and precipitating cell protein
Combines with sulfhydryl groups of cellular proteins
- acts as denaturation
Definition
Slowly bactericidal; bacteriostatic
Examples
Copper, Arsernic, Mercury, Silver, Zinc
Uses
Used on Burns
Definition
1% AgNO3- used for prophylactic agent in Crede’s
Prophylaxis in suspected Ophthlamia neonatorum
(caused Neisseria gonorrhoaea) replaced with
Erythromycin
1% Silver Nitrate
1% Eye Drop Solution
Prevent gonoccal (Neisseria gonorrhoeae)
conjunctivitis in newbors
MOA
Derived by substitution of the four valence
ammonium ion with alkyhalides
Definition
Molecules of phenol (carbolic acid) that have been
chemically substituted, typically by halogen, alkyl,
phenyl or benzyl groups
Not sporidal
Found in germicidal soaps
Type
Agent
Alcohol
(50-70%)
• Ethanol
• Isopropanol
• Benzyl Alcohol
Aldehydes
(in
solutions)
• Formaldehyde (8%)
• Glutaraldehyde (2%)
Halogens
• Tincture of iodine
(2% in 70% alcohol)
Heavy
• Silver Nitrate
Metals
(AgNO3)
Detergent
• Quaternary
Ammonium
Phenolics
• Phenols
• Carbolic Acid
• Lysol
• Hexachlorophene
Gases
• Ethylene Oxide
