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[MT 6320] Clinical Bacteriology Laboratory > [1S] UNIT 1.2 Control of Microbial Growth > Flashcards

[1S] UNIT 1.2 Control of Microbial Growth Flashcards

1
Q

TYPE OF ORGANISM

T/F: The ability of the microorganism to withstand the different disinfecting / sterilizing agents depend on the chemical composition and protective mechanisms inherent to such microorganism.

A

T

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2
Q

Are produced by some bacteria to confer resistance to heat, radiation, and other harsh environmental conditions.

A

Endospores

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3
Q

TYPE OF ORGANISM

T/F: Some bacteria form biofilms that protect them from radiation, desiccation, high pressure, extreme pH temperature, and antimicrobial agents

A

T

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4
Q

Refers to the number of microorganisms present in the specimen/object.

A

Microbial Load

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5
Q

CONCENTRATION OF THE AGENT TO BE USED

T/F: Less concentrated disinfectants are effective in microbial inhibition or killing.

A

F; More concentrated

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6
Q

PRESENCE OF ORGANIC MATERIAL

T/F: Presence of mucus, blood, and pus can inactivate the disinfecting agent by preventing the full contact of the agent and the material to be disinfected.

A

T

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7
Q

PRESENCE OF ORGANIC MATERIAL

Examples of chemical agents that can be inactivated include bleach and ______.

A

Quaternary Ammonium Compound (QUATS)

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8
Q

NATURE OF SURFACE TO BE DISINFECTED

Devised a logical approach for disinfection/sterilization of inanimate objects or surfaces based on the degree of risk involved in their use.

A

Earle Splaulding

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9
Q

NATURE OF SURFACE TO BE DISINFECTED

According to Spaulding classification, equipment/items are regarded as: _______, ___________, __________.

A

Critical
Semi-critical
Non-critical

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10
Q

NATURE OF SURFACE TO BE DISINFECTED

Are devices that enter sterile body parts, including the vascular system

A

Critical Items

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11
Q

NATURE OF SURFACE TO BE DISINFECTED

Are devices that enter sterile body parts, including the vascular system

A

Critical Items

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12
Q

NATURE OF SURFACE TO BE DISINFECTED

Are those that come in contact with non-intact skin or mucous membrane but does not penetrate them

A

Semi-critical Items

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13
Q

NATURE OF SURFACE TO BE DISINFECTED

T/F: High level of disinfection is required for the critical items, while low level of disinfection is implemented for non-critical items

A

T

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14
Q

NATURE OF SURFACE TO BE DISINFECTED

Touches only the intact skin but not the mucous membrane

A

Non-critical Items

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15
Q

Refers to the length of time a chemical agents needs to stay on a targeted surface in order to become an effective disinfectant/sterilant

A

Contact Time

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16
Q

CONTACT TIME

T/F: Applying the chemical agent and wiping it immediately may render it useless in killing or inhibiting growth microorganisms

A

T

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17
Q

TEMPERATURE & PH

T/F: Most disinfectants are effective at room temperature under a basic condition

A

F; acidic condition

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18
Q

TEMPERATURE & PH

T/F: Disinfection can be enhanced by an increase in temperature only up to a certain degree

A

T

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19
Q

TEMPERATURE & PH

T/F: Too much increase in temperature may affect the efficacy of a disinfectant and therefore strengthen its germicidal activity

A

F; weaken

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20
Q

TEMPERATURE & PH

T/F: In chlorination, as pH goes up, the concentration of hypochlorite ions decreases and disinfection becomes less effective

A

F; increases

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21
Q

COMPATIBILITY OF DISINFECTANTS

T/F: QUATS and bleach should not be used together. Mixing it may result in a creation of toxic gas

A

T

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22
Q

What are the factors affecting microbial growth?

A

● Type of Organism
● Microbial Load
● Concentration of Agent to be used
● Presence of Organic Material
● Nature of surface to be disinfected
● Contact time
● Temperature
● pH
● Compatibility of disinfectants

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22
Q

refers to methods employed to prevent entry of organisms into the body as well into test tubes, flasks or plates used in microbial cultivation

A

Aseptic Technique

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23
Q

refers to the absence of microbes in an area or object

A

Asepsis

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24
Q

a condition in which microbial growth and multiplication is halted or inhibited. The microorganism is not killed or destroyed in the process. Include the use of refrigeration as well as dyes.

A

Bacteriostasis

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24
Q

involves chemical disinfection of living tissues (i.e. mucus membrane, skin) as well as in the treatment of wounds. The chemical agent employed is called an _______

A

antiseptic / Antisepsis

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25
Q

T/F: In bacteriostasis, the microorganism is not killed or destroyed in the process.

A

T

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26
Q

are chemical sterilants used to destroy all
forms of life. It is also known as chemical sterilants

A

Biocide

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27
Q

microorganisms inadvertently introduced to specimens or bacterial culture

A

Contaminant

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28
Q

the process of removal of pathogenic microorganisms so materials/items are safe to handle or dispose.

A

Decontamination

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29
Q

removal of transient microorganisms from the skin using mechanical cleansing or antiseptics.

A

Degerming

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30
Q

process of destruction of pathogenic microorganisms except spores, prions and other microorganisms.

A

Disinfection

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31
Q

reduction of pathogens on eating
utensils to safe public health levels by mechanical cleansing or use of chemicals.

A

Sanitization

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32
Q

destruction of all forms of life including bacterial spores.

A

Sterilization

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33
Q

lowest temperature in which all bacteria in a liquid culture will be killed in 10 minutes 1

A

Thermal Death Point

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34
Q

minimal length of time in which all bacteria in a liquid suspension will be killed at a given temperature

A

Thermal Death Time

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35
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: Some surfaces or materials may be damaged. Many medical instruments are damaged by eat or corrosive materials

A

Surface or material to be disinfected

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36
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: Excess dirt, blood, mucus, or pus may inactivate the agent; it may be necessary to clean the surface prior to disinfection

A

Presence of organic material

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37
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: The amount of time the disinfectant is in contact with the surface affects the amount of organism destruction. Betadine must have a contact time of ______ minutes in order to kill microorganisms

A

1 to 2

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38
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: Different type of microorganism may be more resistant to the effects of certain disinfectants. Spores, mycobacteria, prions, and biofilms may require specific agents

A

Organism Type

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39
Q

● Most commonly used method
● Cheap, economical and reliable
● It could either be through MOIST HEAT or DRY HEAT

A

Heat

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39
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: The amount and concentration of disinfectant required to adequately destory microorganism vary by product. Manufacturer instructions regarding preparation and use should always be followed.

A

Concentration of disinfectant

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39
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: The presence of greater amounts of microorganism usually requires greater contact time with the disinfectant

A

Amount of organism present

39
Q

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS

CONSIDERATION: Temperature and pH can alter activity. Most disinfectant require increased contact time in colder temperatures. The pH of the material to be disinfected must be considered, as some disinfectants are only active within a certain range.

A

Temperature and pH

40
Q

2 Sterilization Methods

A

● Physical Means
● Chemical Means

41
Q

Principle of dry heat

A

Oxidation

42
Q

Longer Exposure time and higher temperatures

A

Dry Heat

43
Q

For the sterilization of inoculating loops, needles, mouth of tubes

A

Open Flame

44
Q

DRY HEAT

● HOT AIR OVEN:
● TEMPT REQUIREMENTS:

A

Sterilize Glasswares
160-180C for 1.5-3 hours

45
Q

OPEN FLAME

BUNSEN BURNER:

A

Flame Sterilization

46
Q

● For disposal of hospital waste (infectious)
● Now Outlawed: RA 8749 Clean Air Act of 1999

A

Incineration

47
Q

T/F: In moist heat, all microorganisms are killed except prions

A

T

47
Q

● Or HEAT UNDER STEAM PRESSURE
● More effective than dry heat
● Shorter time of exposure
● Sterilization method of choice for heat stable objects

A

Moist Heat

48
Q

MOIST HEAT

PRINCIPLE:
AUTOCLAVE:

A

Coagulation of Proteins
121C, 15psi (1atm) for 15 minutes

49
Q

● Form of disinfection; DOESN’T KILL SPORES
● 100C for 10-15 minutes

A

Boiling

50
Q

eliminates food borne pathogens responsible for food spoilage

A

Pasteurization

51
Q

PASTEURIZATION METHODS
1. Batch Method:
2. Flash Method
3. High Tempt Short Time

A
  1. 63C for 30minutes
  2. 72C for 15seconds
  3. 72C-140C then 72C for <5sec
52
Q

● Flowing Steam
● Fractional
● Intermittent
● 100C for 30 mins for 3 days
● Arnold’s Sterilizer

A

Tyndallization

53
Q

● for sterilization of high protein media
● 75-80C for 2hrs on 3 consecutive days

A

Inspissation

54
Q

TYPE OF MOIST HEAT: Steam Under Pressure
APPARATUS EMPLOYED: Gravity Displacement
TEMPERATURE: 121C @ 15psi (1 atm)
TIME: 15-20 minutes
APPLICATION: ?

A

Sterilization of Culture Media

54
Q

TYPE OF MOIST HEAT: Steam Under Pressure
APPARATUS EMPLOYED: Gravity Displacement
TEMPERATURE: 121C @ 15psi (1 atm)
TIME: ?
APPLICATION: Biological waste in broth or solid media

A

30 minutes

55
Q

TYPE OF MOIST HEAT: Steam Under Pressure
APPARATUS EMPLOYED: Vacuum Autoclave
TEMPERATURE: 132 @ 15psi (1 atm)
TIME: ?
APPLICATION: Biological waste in broth or solid media

A

4 minutes

56
Q

TYPE OF MOIST HEAT: Steam Under Pressure
APPARATUS EMPLOYED: Vacuum Autoclave
TEMPERATURE: 132 @ 15psi (1 atm)
TIME: 30-60 minutes
APPLICATION: ?

A

Biologic waste (blood/body fluids)

57
Q

TYPE OF MOIST HEAT: ?
APPARATUS EMPLOYED: Arnold’s Sterilizer
TEMP: 100C
TIME: 30 mins for 3 consecutive days with incubation period in between sterilization
APPLICATION: Heat sensitive media that cannot withstand autoclave temperature

A

Tyndallization

58
Q

TYPE OF MOIST HEAT: ?
APPARATUS EMPLOYED: Inspissator
TEMP: 75-80C
TIME: 2 hours for 3 successive days
APPLICATION: High protein media

A

Inspissation

59
Q

TYPE OF DRY HEAT: Incineration
APPARATUS EMPLOYED: ?
TEMP: 870-980C
TIME: -
APPLICATION: Safest method to destroy all microorganisms including prions; applicable for disposal of carcasses and medical wastes

A

Incinerator

60
Q

TYPE OF DRY HEAT: ?
APPARATUS EMPLOYED: Dry heat oven
TEMP: 160-180C / 121C
TIME: 1.5-3 hrs / 16 hrs
APPLICATION: For glassware, oils, petroleum, powder

A

Hot Air Sterilization

61
Q

TYPE OF DRY HEAT: ?
APPARATUS EMPLOYED: Bunsen burner or alcohol lamp / Bacti-cinerator sterilizer
TEMP: - / approx. 815.6C
TIME: until red hot (for loop & needle)
APPLICATION: Sterilization of inoculation needle, loops, tips of metal forceps

A

Direct Flaming

62
Q

Separation of bacteria from liquids or air

A

Filtration

63
Q

FILTRATION OF LIQUIDS: through Berkefeld

A

diatomaceous earth

64
Q

FILTRATION OF LIQUIDS: through
○ Morton: _____ ______
○ Seitz: ______ ____

A

sintered glass
asbestos pad

65
Q

FILTRATION OF LIQUIDS: through
○ Chamberland-Pasteur: ______ _____
○ Membrane Filters: ________ _____

A

unglazed porcelain
Cellulose esters

66
Q

For critical sterilization: ______ filter must be used

A

0.22um

67
Q

FILTRATION OF AIR through: ?
○ able to remove organisms >0.3um
○ Uses: Laboratory hoods, rooms of
immunodeficient patients

A

HEPA (High Efficiency Particulate Air Filters)

68
Q

MOA: alkylation of Nucleic acid

A

Radiation

69
Q

● Gamma rays or electron beams
● Short wavelength but high energy
● USE: Sterilization of disposable materials in the medical industry

A

Ionizing Radiation

70
Q

● UV rays
● Long wavelength but low energy
● Poor penetration
● USE: disinfection of surfaces

A

Non-ionizing

71
Q

PHYSICAL METHODS
● dehydration
● removal of water to stop metabolic action of bacteria

A

Dessication

72
Q

PHYSICAL METHODS
○ through PLASMOLYSIS
○ high concentrations of sugar/salt

A

High Osmotic Pressure

73
Q

PHYSICAL METHODS
○ bacteriostatic

A

Exposure to Low Temperature

74
Q

CHEMICAL METHODS
○ cold sterilization
○ gas chamber (450-700 mg/L), 55-60C
○ minimum time: 2hours
○ Principle: Alkylation of nucleic acids

A

GASEOUS CHEMICALS: ETHYLENE OXIDE

75
Q

CHEMICAL METHODS
○ shorter contact time of killing

A

GASEOUS CHEMICALS: Hydrogen Peroxide and Periacetic Acid

76
Q

CHEMICAL METHODS
○ Mode of Action: Protein Denaturation and Lipid Dissolution
○ 70% ETHANOL

A

Alcohols

77
Q

CHEMICAL METHODS

Mode of Action: Alkylation of Nucleic Acids and Protein Denaturation
■ 2% GLUTARALDEHYDE: disinfectant
■ 40% FORMALIN

A

Aldehydes

78
Q

CHEMICAL METHODS

○ Mode of Action: Cytoplasmic Membrane Destruction
○ Uses: Commonly used antiseptic in surgery

A

Chlorhexidine

79
Q

CHEMICAL METHODS

● Mode of Action: Oxidation of cellular Components and Protein Denaturation
● Iodine

A

Halogens

80
Q

HALOGENS

alcohol and iodine solutions for antiseptics

A

Tincture

81
Q

HALOGENS

● iodine plus a neutral polymer carrier
● must be diluted
● Preferrable
● ex. POVIDONE-IODINE (“BETADINE”)

A

Iodophors

82
Q

HALOGENS

■ one of the oldest and common disinfectants
■ In the form of : HYPOCHLORITE
● not used as sterilants
■ Dilution: 1:10 dilution of 5.25%

A

Chlorine

83
Q

CHEMICAL METHODS: WATER STERILIZATION

Bleach:Water

A

2-3 drops bleach in 1 L of water for 30 minutes

84
Q

CHEMICAL METHODS: WATER STERILIZATION

Addition of Chlorine in swimming pools and in drinking water

A

Copper Sulfate Pentahydrate

85
Q

CHEMICAL METHODS: WATER STERILIZATION

Collection for Water Testing

A

Add Sodium Thiosulfate

86
Q

CHEMICAL METHODS

○ Rarely used, bacteriostatic
○ Mode of Action: protein and enzyme inactivation

A

Heavy Metals

87
Q

CHEMICAL METHODS: HEAVY METALS

■ Mercury: ?
■ Silver: ? (Crede’s Prophylaxis)
■ Copper: ? – anti-algae

A

Merthiolate
1% Silver Nitrate
Copper Sulfate

88
Q

CHEMICAL METHODS

Mode of Action: oxidation of cellular components
■ Hydrogen peroxide
■ Ozone

A

Oxidizing Agents

89
Q

CHEMICAL METHODS

○ Mode of Action: Protein denaturation, cell
membrane andenzyme inactivation
○ Chemically substituted phenol compounds
○ Less toxic and more effective
■ Examples: ortho-phenylphenol and ortho-benzyl-para-chlorophenol
■ Uses: Hospital and institutional disinfection

A

Phenolic Compounds

90
Q

CHEMICAL METHODS

○ Mode of Action: Protein denaturation, cell
membrane andenzyme inactivation
○ Chemically substituted phenol compounds
○ Less toxic and more effective
■ Examples: ortho-phenylphenol and ortho-benzyl-para-chlorophenol
■ Uses: Hospital and institutional disinfection

A

Phenolic Compounds

91
Q

CHEMICAL METHODS

Mode of Action: interruption of electron
transport, enzyme inhibition and membrane destruction

A

Hexachlorophene

92
Q

CHEMICAL METHODS

○ Effective against Gr (+)
○ Residual effect
○ TOXIC

A

Hexachlorophene

93
Q

CHEMICAL METHODS

○ Mode of Action: cell wall disruption and enzyme inactivation
○ Effective against Gr (+)
○ Not affected by organic compunds

A

Chloroxylenol

94
Q

● Mode of Action: protein denaturation and cell
membrane destruction
● surface active agents; reduce surface tension
● inactivated by organic compounds and hard water (ex. Benzalkonium Cl (Zephiran), Cetylperidium Chloride)
○ Resistant to M. tuberculosis

A

QUATS

95
Q

● Mechanical Action by rubbing and scrubbing
○ Possess antibacterial ingredients such as triclocarbon or triclosan

A

Soaps & Detergents

96
Q

How to check the effectiveness of physical methods?

A

Through the use of spore strips & determination of phenol coefficient

97
Q

EFFECTIVENESS OF PHYSICAL METHODS

Bacillus subtilis var. niger

A

HOT-AIR OVEN

98
Q

EFFECTIVENESS OF PHYSICAL METHODS

Bacillus subtilis var. globigii

A

Ethylene Gas

99
Q

EFFECTIVENESS OF PHYSICAL METHODS

Bacillus pumilus

A

Ionizing Radiation

100
Q

EFFECTIVENESS OF PHYSICAL METHODS

Bacillus stearothermophilus

A

Autoclave

[MT 6320] Clinical Bacteriology Laboratory (3 decks)

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