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Chapter 7 Part 1 > Ya Allah > Flashcards

Ya Allah Flashcards

1
Q

What’s a bio burden

A

is an estimate of total viable count of M.Os present pre-sterilization

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2
Q

What are the methods to reduce the number of MO

A

– Sterilization
– Disinfection
– Antiseptic

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3
Q

What is sterilisation

A

The process of destroying all forms of microbial life on an object or in a material. This includes the destruction of
endospores

IT IS ABSOLUTE

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4
Q

What are the typical temperatures for sterilisation

A

Moist heat at 121 for 15mins

Dry heat 170 for 120 mins

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5
Q

What does disinfection means

A

The process of destroying vegetative pathogens, but not necessarily endospores or viruses

It’s not usually sterilize

Disinfectant= non-living objects

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6
Q

What’s an antiseptic

A

Chemical disinfections of the skin, mucous membranes, or other living tissues. This term is especially applied to treatment of wounds.

Antiseptic= living

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7
Q

What is commercial sterilisation

A

is heat treatment of canned foods to destroy the
endospores of Clostredium botulinum

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8
Q

What does degerming means

A

is removal of microbes from limited

area

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9
Q

What are the factors that effect antimicrobial activity

A
  1. Temp
  2. Time
  3. Concentration of Antimicrobial agent
  4. Type of Microbe
  5. Activity of Microbe
  6. Presence of organic matter
  7. Microbial inoculum
  8. Microbial Phenotype (planktonic vs biofilm)
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10
Q

What are the physical methods of sterilisation

A

1.heat(moist and dry)
2. Filtration
3. Desiccation
4. osmotic pressure
5. Radiation
• Ionizing Radiation
• Non-Ionizing Radiation

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11
Q

What are the moist heat methods

A

Boiling Water
• Steam Heat (Autoclave)
• Pasteurization (Heat)
• Tyndallization

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12
Q

What are the dry heat methods

A
  • Direct Flaming
  • Incineration
  • Hot Air Sterilization (Oven)
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13
Q

How does heat sterilisation work

A

❖works by denaturing enzymes and proteins

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14
Q

What are the following
TDP
TDT
DRT(D VALUE)

A

A. Thermal Death Point (TDP)
– lowest temp. at which all microorganism in a liquid culture are killed in 10 minutes

B. Thermal Death Time (TDT)
– minimum length of time in which all microorganisms in a liquid culture are killed at a given temperature

C. Decimal reduction time (DRT, or D value: survival curve)
– time needed to kill 90% of living microbes

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15
Q

The higher the D value the more resistant the bacteria

A

True

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16
Q

How does boiling work

A

Kills microorganisms by irreversibly coagulatingn their proteins.

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17
Q

What does boiling kill

A

vegetative forms of bacterial pathogens,
–many viruses, and fungi and their spores within about 10 minutes.

not effective for endospores and some viruses
– Hepatitis (20 min)
– Some spores may survive boiling water for up to 20 hrs

18
Q

How can we reach higher temperatures

A

by steam under pressure in an autoclave

The higher the pressure the higher the temperature

19
Q

What’s the time and pressure in an autoclave at 121

A

15 psi

15mins

20
Q

What’s flash autoclaving

A

Flash autoclaving sterilizes at 135°C and 35psi in 3 minutes

21
Q

What is classic pasteurization

A

milk was exposed to a temperature of about 63oC for 30 minutes

22
Q

What is HTST

A

Milk treatmentat least 72o C, but for only about 15 seconds

23
Q

How do we determine of a product is pasteurised

A

Phosphatase test (enzyme in the milk)

If the product pasteurized this enzyme will be
inactivated

24
Q

What is UHT pasteurization

A

The milk falls in a thin film through a chamber of superheated steam reach 140 C in less than secondnand hold for 4 seconds then cooled in a vacuum chamber

  • Within 5 seconds;
  • 74 °C ———–140 C ————-74 C
25
Q

What is tyndallization

A

Exposure of the material to free-flowing steam at 100 C for 20 minutes on 3 consecutive days with intermittent incubation at 37

it is used only for sterilization of materials that are composed of ther molabile chemicals and that might be subject to decomposition at higher temperatures

26
Q

What is direct flaming (dry heat)

A

Inoculating Loop and Needle 100% effective

نفس اللاب

27
Q

What is incineration (dry heat)

A

disposable wastes (paper cups, bags, dressings) and burning them to ashes

28
Q

What is hot air sterilisation (oven)

A

Generally, a temperature of 170o C is maintained for 2 hours.

does not dull or rust metals, however, it is not time
efficient

29
Q

What is filtration sterilisation

A

Sterilization by removing rather than destroying the M.O used for liquids and gases

30
Q

What are the applications for filtration

A
  1. Heat sensitive injections and ophthalmic solutions
  2. Biological products
  3. Air and gases for supply to aseptic areas
31
Q

What are the types of membrane filters

A
  1. Cellulose acetate, Cellulose nitrate

2. polyethersulfone, polycarbonate, polyvinylidene fluoride

32
Q

What are the pore sizes

A

0.2µm

But sterility test (0.45µm)

33
Q

What is HEPA

A

HEPA (High efficiency particulate air) filter, high efficiency particulate
air
• Can remove 99.997% of particles> 0.3 µ

34
Q

What is desiccation

A
  • Absence of water
  • M.O can not grow but remain viable for years
  • Lyophilization (freeze drying)
  • Mech.of action by disruption of metabolism
  • Bacteriostatic
35
Q

What is osmotic pressure sterilisation

A

Hypertonic solution———–plasmolysis
• Resulted in loss of water from microbial cell
• Used in food preservation

36
Q

What does radiation effect depends on

A
  1. Wavelength
  2. Intensity
  3. duration
37
Q

What is ionising radiation

A

ionization of
water which give free OH radicals which is very
reactive
• React with organic cellular component especially
DNA
• Mutation then killing

38
Q

Give examples on ionising radiation

A

gamma rays , x-rays & high energy electron beams
• penetrates most substances
• Wavelength< 1 nm

39
Q

What can we use ionising radiation on

A 
Used on substances that could be damaged by heat
– plastic petri dishes
– plastic syringes
– catheters
– surgical gloves
40
Q

Gamma rays penetrate deeply but requier hrs to
sterilize large masses
• high energy electron beams has lower penetrating power but require few seconds of exposure

A

True

Chapter 7 Part 1 (1 decks)

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