Module 4 Flashcards
1
Q
Why control growth of microorganisms?
A
- prevent spoilage of important commodities
- prevent infection
- prevent contamination of cultures, personnel, and environment
2
Q
complete destruction of all microorganisms, including endospores
A
STERILIZATION
3
Q
- killing, inhibition, or removal of pathogenic microorganisms
A
DISINFECTION
4
Q
inanimate objects that harbor microorganisms
A
Fomites
5
Q
Reduction of microbial population to levels considered safe by public health standards
A
SANITIZATION
6
Q
preventing infections in living tissues using chemicals
A
ANTISEPSIS
7
Q
Agents that carry out antisepsis
selectively effective against microorganisms; does not cause tissue damage
A
ANTISEPTICS
8
Q
mechanical removal + use of
mild chemicals on tissues or
skin
A
DEGERMING
9
Q
Agents Used in Microbial Control
A
PHYSICAL or CHEMICAL
10
Q
Physical Methods to Control Microorganisms
A
Application of Heat
Filtration
Desiccation
Addition of Solutes
Radiation
11
Q
Chemical Methods to Control Microorganisms
A
Antimicrobial agents
Phenols and phenolics
Alcohols
Halogens
Heavy Metals
Surfactants
Organic Acids
Alkylating Agents
Peroxygens
12
Q
- MOA: denatures proteins and other cellular components
- Moist or Dry Heat
A
Application of Heat
13
Q
- MOA: irreversible
denaturation of enzymes and
structural proteins - more effective in penetrating
cells
A
Moist Heat
14
Q
Types of Moist Heat
A
Boiling
Steam under pressure
Tyndallization
Pasteurization
15
Q
- kills vegetative cells and
eukaryotic spores - sterility is not achieved
A
Boiling
16
Q
- uses autoclave or pressure
cooker - 121 ̊C, 15 psi, for 15 minutes
A
Steam under pressure
17
Q
Indicators to ensure sterility:
A
autoclave tape
Geobacillus stearothermophilus spores
18
Q
- intermittent or fractional sterilization
- for materials destroyed beyond 100̊C
A
Tyndallization
19
Q
Process of Tyndallization
A
- heating to 100 ̊C for 15 to 30 minutes
- done for 3 consecutive days
20
Q
- kill pathogens and reduce the
number spoilage
microorganisms
A
Pasteurization
21
Q
basis of pasteurization
A
Coxiella burnettii
22
Q
Ways of pasteurization
A
LTLT – 63 ̊C, 30 minutes
HTST - 72 ̊C, 15 seconds
UHT - 135 to 140 ̊C, 1 to 2 seconds
23
Q
Types of Dry Heat
A
Direct Flame
Hot Air
24
Q
- MOA: incineration or burning to ashes
- Alcohol lamps, Bunsen burner, Bactericinerator
A
Dry Heat – Direct Flame
25
* MOA: oxidation of molecular components
* 170 ̊C for at least 2 hours
* mechanical convection oven
Dry Heat – Hot Air
26
* Refrigeration – 4 to 7 ̊C
* Freezing - 0 ̊C and below
* MOA: decreased enzyme
activity = decrease in
metabolic activity
Low Temperature
27
group of organisms with the ability to grow and reproduce under low temperatures ranging from −20 °C to 10 °C
psychrophiles
28
* MOA: exclusion of
microorganisms
* common pore size: 0.2 μm
* for heat sensitive solutions
Filtration
29
MOA: lowering of aw = microbiostasis
Desiccation
30
types of Desiccation
Drying
Freeze drying or lyophilization
31
- sunlight, drum drying,
spray drying, evaporation
Drying
32
rapid freezing then sublimation
Freeze drying or lyophilization
33
* MOA: osmotic shock
* increase in solutes such as
salts and sugars
Addition of Solutes
34
types of radiation
Ionizing Radiation
Non-Ionizing Radiation (UV Radiation)
Sunlight
35
* Shorter wavelength; strong penetrating power
* MOA: double strand breaks in DNA
* Gamma rays, X-rays, High-energy Electron Beam
* for materials that cannot be autoclaved
Radiation – Ionizing Radiation
36
* Longer wavelength; lower energy
* MOA: formation of thymine dimers
* Poor penetrating power – surface disinfection
Non-Ionizing Radiation
* Ultraviolet (UV) radiation
37
* UV and visible light
* MOA: thymine dimers and
oxidation
Radiation – Sunlight
38
* natural or synthetic chemicals
* used to destroy or inhibit microorganisms
Antimicrobial agents
39
* substances that kills microorganisms
bactericidal, fungicidal, viricidal
Antimicrobial agents
-cidal (Latin cida = kill)
40
* prevent growth
microorganisms
bacteriostatic, fungistatic,
viristatic
Antimicrobial agents
-static (Latin statikos = stopping)
41
benzene ring with –OH group
Phenol
42
compounds that have phenol in their chemical structure; more stable
Phenolics
43
* MOA: membrane disruption and
proteins denaturation
* e.g. thymol, eucalyptol, cresols
Phenols and phenolics
44
MOA: inhibition of fatty acid-
biosynthesis pathway
Triclosan (Phenols and phenolics)
45
* MOA: protein denaturation
* most effective at 70% concentration
* bactericidal, fungicidal, viricidal (enveloped viruses)
Alcohols
46
* belong to Group VIIA
* e.g. iodine, chlorine, fluorine
Halogens
47
* MOA: oxidation of cellular
components
* complexed to form iodophors
* e.g. povidone-iodine
Halogens - Iodine
48
* MOA: oxidation of cellular
components
* e.g. Hypochlorous acid and
sodium hypochlorite (bleach)
Halogens - Chlorine
49
* 5.25% to 6.15% sodium hypochlorite
* diluted to 1:100 (1/4 cup of bleach in a gallon of water)
* recommended in disinfecting
surfaces against the SARS-CoV-2
virus
Bleach
50
* MOA: inference of metabolism
Halogens - Fluorine/Fluoride
51
* MOA: protein denaturation
* Oligodynamic
* does not show selective
toxicity
Heavy Metals
52
types of heavy metals
Mercury
Silver
Copper
Zinc
Metal-based nanoparticles
53
* was used to treat syphilis
* e.g. mercurochrome and merthiolate
Heavy Metals - Mercury
54
* combined with antibiotics
* coating in medical supplies
Heavy Metals - Silver
55
* used to control algal growth
Heavy Metals - Copper
56
* Zinc chloride – mouthwash
* Zinc oxide – antiseptic cream
* Zinc pyrithione
– antidandruff shampoo
– psoriasis and acne treatment
Heavy Metals - Zinc
57
* MOA: membrane disruption
oxidation
Heavy Metals - Metal-based nanoparticles
58
* used as coatings on appliances
Silver-nanoparticles
59
* lowers surface tension of liquids
MOA: physical removal of microorganisms
Surfactants
60
-long chain fatty acids that have both polar and nonpolar regions
Surfactants - Soap
61
-negatively charged anion at one end attached to a long hydrophobic chain
Surfactants - Anionic Detergent
62
-positively charged organic ions
responsible for the surface activity
- e.g. Quaternary Ammonium Compounds (Quats)
Surfactants - Cationic Detergents
63
* MOA: disruption of membrane integrity
* quaternary nitrogen atom that confers the positive charge
* e.g. benzalkonium chloride and cetylpyridinium
chloride
Quaternary Ammonium Compound (QUATS)
64
* preservatives
* flavorless, nontoxic, and readily metabolized
* Applications: food and cosmetics
Organic Acids
65
MOA: inhibition of cellular enzymes
Organic Acids - Sorbic acid
66
MOA: oxidative phosphorylation &
amino acid uptake interference
Organic Acids - Benzoic acid
67
MOA: inhibition of metabolic enzymes
Organic Acids - Propionic acid
68
MOA: nucleic acid and enzyme inactivation
Alkylating Agents
69
types of alkylating agents
Aldehydes
Ethylene Oxide
70
Types of aldehydes
Formaldehyde
Glutaraldehyde
o-phthalaldehyde (OPA)
71
-used in solution at a conc. of 37%
(formalin)
- storage of tissue specimens, embalming fluid, and in vaccine preparation
Aldehydes - Formaldehyde
72
-two reactive aldehyde group
- surgical and medical equipment
Aldehydes - Glutaraldehyde
73
minimal odor and more effective against mycobacteria
Aldehydes - o-phthalaldehyde (OPA)
74
* Sterilizing gas
* Strong penetrating capability
* Sterilization of items within plastics
Alkylating Agents - Ethylene Oxide
75
* MOA: oxidation of cellular components
* Disinfectant /antiseptic
Peroxygens
76
Types of Peroxygens
Hydrogen Peroxide
Benzoyl peroxide
Carbamide peroxide
77
* effective against bacteria, fungi,
viruses, and endospores (extended
exposure)
* Bubbling – production of oxygen and water
Hydrogen Peroxide
78
-acne medication solutions
Benzoyl peroxide
79
toothpaste
Carbamide peroxide
80
time needed to kill a given number of organisms at a specified temperature
Thermal death time
81
- time required to destroy 90% of the organisms
Decimal reduction time (D value)
82
- used to compute for the equivalent thermal processes at different temperatures
z value
83
- smallest amount of agent needed to inhibit the
growth of a test organism
Minimum inhibitory concentration (MIC)
84
Factors affecting the effectiveness of microbial control
* Population Size
* Population Composition
* Concentration of Agent
* Exposure time
* Temperature
* Other intrinsic and extrinsic factors
