MICROBIOLOGY > EXERCISE 5 > Flashcards

EXERCISE 5 Flashcards

(38 cards)

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1
Q

STERILIZATION VS DISINFECTION

  1. process
  2. physical or chemical means (2)
A

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

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2
Q

4 types of CHEMICAL sterilization

A

Ethylene oxide

Glutaraldehyde

Hydrogen peroxide

Ozone

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3
Q

what do you call CHEMICALS that:
1. kill organisms
2. inhibit growth

A
  1. cidal agents
  2. static agents
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4
Q

3 PHYSICAL methods of sterilization

A
  1. Heat
  2. Filtration
  3. Radiation
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5
Q

3 TYPES of HEAT STERILIZATION

-> MOA (2; 2; 3)
-> USE (3; 6; 2)

A
  1. Direct Heat/Flaming
    - oxidation of chemical constituents
    - burning to ashes
    -> wire loops, needles, and glass rods
  2. Dry Heat
    - oxidation of chemical constituents
    - burning to ashes
    -> glassware, porcelain/ceramicware, surgical instruments, powders, anhydrous oils, paper-wrapped itemss
  3. Moist Heat
    - degrades nucleic acids
    - denatures proteins and enzymes
    - disrupts cell membrane
    -> culture media and glassware
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6
Q

WHAT is commonly used to sterilize SMALL EQUIPMENT to manipulate bacteria aseptically

A

FLAMING

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7
Q

DISADVANTAGES of direct flame (2) + how to counter

method that works well for 2nd disadvantage

A

1.during flaming, infectious material may spatter from wire loops
2.gas flames may leave residue

  1. special heaters (heated cages -> surround loop)
  2. dip object in 70/95% ethanol and ignite quickly
    (works well for NON-POROUS GLASS “hockey stick”-shaped or L-rods)
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8
Q

WHAT destroys microorganisms by causing coagulation of proteins

A

DRY HEAT

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9
Q

DRY HEAT
- what equipment is used for dry heat (like san linalagay yung mga sinesterilize)
- ideal TEMP and TIME

A
  • hot air oven
  • 160-170 C for 2-3 hrs holding time
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10
Q

WHAT TYPE OF HEAT STERILIZATION is one of the earliest forms of sterilization practices

A

DRY HEAT

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11
Q

WHAT STERILIZATION uses hot air that is FREE from water vapor or has limited amount

A

DRY HEAT

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12
Q

WHAT is fitted within a HOT AIR OVEN to:
1. ensure even distribution of hot air
2. maintains chamber air at chosen temperature

A
  1. fan
  2. thermostat
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13
Q

Advantages (5) & Disadvantages (3) of DRY HEAT

A

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

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14
Q

Precautions when using DRY HEAT OVEN (7)

A
  1. not overloaded
  2. arranged to allow free air circulation
  3. materials to be sterilized should be DRY
  4. test tubes & flasks NEED to be fitted w cotton plugs
  5. petri dish and pipette should wrapped properly in paper
  6. not allowed - rubber and inflammable materials
  7. after heating, 2 hr cool down is needed to avoid glass breaking
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15
Q

WHAT TYPE OF HEAT STERILIZATION is carried out at high temperature to destroy resistant forms (endospores)

A

Moist Heat

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16
Q

WHAT TYPE OF HEAT STERILIZATION requires use of saturated steam

17
Q

WHAT TYPE OF HEAT STERILIZATION is most widely used, economical, and dependable method

18
Q

what DOES moist heat commonly sterilizes (2)

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A

biohazardous trash
aqueous preparation of culture media

19
Q

MOIST HEAT
- equipment used
- temp. pressure. and time

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A
  1. autoclave
  2. 121 C, 15 psi, 15 mins
20
Q

PRINCIPLE of moist heat sterilization

Temperature at which ____ occurs is ______ proportional with the amount of ____ present

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A

denaturation
inversely
moisture

21
Q

Purpose of PRESSURE in moist heat

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A

means to obtain HIGH TEMPERATURE necessary to quickly kill microorganisms

22
Q

MOIST HEAT

When should u start worrying abt the minimum sterilization time

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A

kapag all materials have reached sterilization at the reuired temperature

23
Q

what is the KEY to autoclaving (moist heat)

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A

temp must be high enough to kill resistant structures

24
Q

TEMPERATURE, PRESSURE, and TIME

Correlation in MOIST HEAT

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A

TEMP - adjusted and monitored
PRESSURE - used to reach the temp
TIME - monitored after required temp is reached

25
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
26
DRY HEAT vs MOIST HEAT in terms of: 1. temperature 2. rate of heat penetration
D: higher temperature -> slower rate M: lower temp but higher water pressure -> faster rate
27
WHAT TYPE of sterilization uses filters with pores that do not allow bacterial cells to pass thru
filtration
28
pore size of FILTERS in FILTRATION STERILIZATION
0.2 - 0.45 um in diametr
29
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)
30
EQUIPMENT used in FILTRATION
High-efficiency particulate air filters
31
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
32
2 types of RADIATION STERILIZATION + EXAMPLES (2; 1) + MOA (3; 2)
1. Ionizing radiation - x and g rays - DNA damage - penetrates deep into materials (shorter wavelenght) - formation of free radicals 2. Non-ionizing Radiation - UV - DNA damage from THYMINE DIMERS - low penetration power
33
MOA of chemical sterilization (2)
- disrupts plasma membrane - denature proteins
34
What chemical agent is SELDOMLY used due to bad odor
Phenol
35
what do you call the thing that u disinfect
fomite
36
example of a natural disinfecatant
vinegar
37
4 factors affecting efficacy of disinfectants
1. type, number, and location of microbes 2. concentration and nature of disinfectant 3. length of treatment 4. temp and other physical and chemical factors
38
MINIMUM EXPOSURE TIME FOR dry heat moist heat according to experiments
DH: 160 C for 1 hr MH: 121 C for 5 mins
MICROBIOLOGY
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