EXERCISE 5 Flashcards
STERILIZATION VS DISINFECTION
- process
- physical or chemical means (2)
S: destroys all living forms thru both physical and chemical means
D: inhibit growth of microorganisms thru chemical means
: only destroy susceptible vegetative cells -> endospores & viruses may still live
4 types of CHEMICAL sterilization
Ethylene oxide
Glutaraldehyde
Hydrogen peroxide
Ozone
what do you call CHEMICALS that:
1. kill organisms
2. inhibit growth
- cidal agents
- static agents
3 PHYSICAL methods of sterilization
- Heat
- Filtration
- Radiation
3 TYPES of HEAT STERILIZATION
-> MOA (2; 2; 3)
-> USE (3; 6; 2)
- Direct Heat/Flaming
- oxidation of chemical constituents
- burning to ashes
-> wire loops, needles, and glass rods - Dry Heat
- oxidation of chemical constituents
- burning to ashes
-> glassware, porcelain/ceramicware, surgical instruments, powders, anhydrous oils, paper-wrapped itemss - Moist Heat
- degrades nucleic acids
- denatures proteins and enzymes
- disrupts cell membrane
-> culture media and glassware
WHAT is commonly used to sterilize SMALL EQUIPMENT to manipulate bacteria aseptically
FLAMING
DISADVANTAGES of direct flame (2) + how to counter
method that works well for 2nd disadvantage
1.during flaming, infectious material may spatter from wire loops
2.gas flames may leave residue
- special heaters (heated cages -> surround loop)
- dip object in 70/95% ethanol and ignite quickly
(works well for NON-POROUS GLASS “hockey stick”-shaped or L-rods)
WHAT destroys microorganisms by causing coagulation of proteins
DRY HEAT
DRY HEAT
- what equipment is used for dry heat (like san linalagay yung mga sinesterilize)
- ideal TEMP and TIME
- hot air oven
- 160-170 C for 2-3 hrs holding time
WHAT TYPE OF HEAT STERILIZATION is one of the earliest forms of sterilization practices
DRY HEAT
WHAT STERILIZATION uses hot air that is FREE from water vapor or has limited amount
DRY HEAT
WHAT is fitted within a HOT AIR OVEN to:
1. ensure even distribution of hot air
2. maintains chamber air at chosen temperature
- fan
- thermostat
Advantages (5) & Disadvantages (3) of DRY HEAT
A:
1. non-toxic
2. environment-safe
3. gently and thoroughly penetrates material
4. non-corrosive (compatible w metal)
5. low operating cost
D:
1. slow rate of heat penetration
2. requires extremely high temperature
3. overexposure may ruin items
Precautions when using DRY HEAT OVEN (7)
- not overloaded
- arranged to allow free air circulation
- materials to be sterilized should be DRY
- test tubes & flasks NEED to be fitted w cotton plugs
- petri dish and pipette should wrapped properly in paper
- not allowed - rubber and inflammable materials
- after heating, 2 hr cool down is needed to avoid glass breaking
WHAT TYPE OF HEAT STERILIZATION is carried out at high temperature to destroy resistant forms (endospores)
Moist Heat
WHAT TYPE OF HEAT STERILIZATION requires use of saturated steam
MOIST HEAT
WHAT TYPE OF HEAT STERILIZATION is most widely used, economical, and dependable method
MOIST HEAT
what DOES moist heat commonly sterilizes (2)
biohazardous trash
aqueous preparation of culture media
MOIST HEAT
- equipment used
- temp. pressure. and time
- autoclave
- 121 C, 15 psi, 15 mins
PRINCIPLE of moist heat sterilization
Temperature at which ____ occurs is ______ proportional with the amount of ____ present
denaturation
inversely
moisture
Purpose of PRESSURE in moist heat
means to obtain HIGH TEMPERATURE necessary to quickly kill microorganisms
MOIST HEAT
When should u start worrying abt the minimum sterilization time
kapag all materials have reached sterilization at the reuired temperature
what is the KEY to autoclaving (moist heat)
temp must be high enough to kill resistant structures
TEMPERATURE, PRESSURE, and TIME
Correlation in MOIST HEAT
TEMP - adjusted and monitored
PRESSURE - used to reach the temp
TIME - monitored after required temp is reached
ADVANTAGES (4) and DISADVANTAGES (4) of MOIS HEAT
A:
1. non-toxic
2. easy to control and monitor
3. fast results
4. inexpensive
D:
1. damaging to heat-sensitive materials
2. may leave materials wet -> cause rusting
3. repeated exposure to moisture -> cause damage
4. potential for burns
DRY HEAT vs MOIST HEAT in terms of:
- temperature
- rate of heat penetration
D: higher temperature -> slower rate
M: lower temp but higher water pressure -> faster rate
WHAT TYPE of sterilization uses filters with pores that do not allow bacterial cells to pass thru
filtration
pore size of FILTERS in FILTRATION STERILIZATION
0.2 - 0.45 um in diametr
MOA (1) and USE (6) of FILTRATION
MOA : physical removal of microorganisms
USE: heat sensitive fluids and w low concentration count (enzymes, proteins, carbs, antibiotics, toxic chemicals, vaccines)
EQUIPMENT used in FILTRATION
High-efficiency particulate air filters
ADVANTAGES (3) and DISADVANTAGES (4) of filtration
A:
1. fewer materials and equipment
2. for heat-sensitive solutions
3. Fast results (large volumes can be filtered quickly)
D:
1. only for liquids and gases
2. filters themselves are expensive
3. filters are easily damaged compared to others
4. clog easily
2 types of RADIATION STERILIZATION
+ EXAMPLES (2; 1)
+ MOA (3; 2)
- Ionizing radiation
- x and g rays
- DNA damage
- penetrates deep into materials (shorter wavelenght)
- formation of free radicals - Non-ionizing Radiation
- UV
- DNA damage from THYMINE DIMERS
- low penetration power
MOA of chemical sterilization (2)
- disrupts plasma membrane
- denature proteins
What chemical agent is SELDOMLY used due to bad odor
Phenol
what do you call the thing that u disinfect
fomite
example of a natural disinfecatant
vinegar
4 factors affecting efficacy of disinfectants
- type, number, and location of microbes
- concentration and nature of disinfectant
- length of treatment
- temp and other physical and chemical factors
MINIMUM EXPOSURE TIME FOR
dry heat
moist heat
according to experiments
DH: 160 C for 1 hr
MH: 121 C for 5 mins
