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BIO233 > Controlling Microbial Growth > Flashcards

Controlling Microbial Growth Flashcards

1
Q

Heat and radiation are examples of what kidn of control method

A

Physical agents

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2
Q

Sterilzation and disnifection are what kind of control method

A

(gas) chemical agents

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3
Q

Filtration is a kind of

A

Mecahnical removal m=of microbes

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4
Q

Sterilization

A

Destruction/removal of all forms of microbial life from and object

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5
Q

Physical processes of sterilization

A

Filtration
High temp
Incineration
Irradiation by UV or gamma rays

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6
Q

Chemical processes of sterilization

A

Ethylene oxide (used in hospitals)
Chlorine dioxide (decontamination of buildings)
Steam sterilization (microbiology)

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7
Q

Mechanical processes of sterilization

A

filtration

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8
Q

Disinfection

A

Broad defintion
includes sanitization and antisepsis

Use of chemicals (disinfectants) to kill or inhibit microorganisms that cause disease

Does not kill all microorganisms
Usually toxic and injurious to human tissues

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9
Q

Widely use Chemicals disinfectants:

A

Chlorine (water supplies)
Phenols,
Biphenols (chlorhexidine),
Alcohols
Iodine
Aldehydes
Quats (quaternary ammonium salts)
Ozone and UV light (newer means)

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10
Q

Sanitization

A

Related to disinfection, but sanitization only reduces the microbial population to acceptable standards.
Restaurants/cafeterias sanitize eating utensils to acceptable public health standards.

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11
Q

Antisepsis

A

Related to disinfection, but used on living tissues
Chemicals used to treat or prevent infection of living tissues (still toxic)
Ex.
Alcohol
Iodine
Chlorhexidine
Heavy metals

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12
Q

Antimicrobial agents

A

Agents that kill or inhibit the growth of microorganisms (cidal or static)

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13
Q

Cide

A

suffix indicating agent kills organisms

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14
Q

Biocide or germicide kills

A

Kill microorganisms

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15
Q

Virocide

A

Inacivates viruses

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16
Q

Static

A

agent that inhibit growth
Bacteriostatic agent: (inhibits) growth of bacteria

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17
Q

Sepsis

A

Bacterial contamination

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18
Q

Aesepsis

A

Absence of significant contamination

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19
Q

Aseptic techniques

A

Methods that minimizes contamination

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20
Q

Factors affecting antimicrobial effectiveness

A

Population size: Large the population (Of microorganisms) = Longer to kill

Population composition: Different sensitivity to antimicrobials

Concentration or intensity: Higher conc, = greater effect
EXCEPT alcohol 70% is more effective than 100%
Time of exposure: Longer exposure = more organisms killed

Environmental conditions
High tem (more killing)
Organic material (decreased killing)
Sewage (reduce effeeiveness of disinfectants), biofilms
Microbial chaaraceristics: Spores more resistant than vegetative cells

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21
Q

Is Gram - or Gram + more resistant

A

Gram - more resistant than Gram + bacteria

Most antimicrobial agents tend to be water soluble, therefore, they cannot easily cross plasma membranes SO Gram - outer layer keeps them out
Pseudomonas aeruginosa - MOST resistant Gram - (Affects burn victims and causes Cystic fibrosis)
Cystic Fibrosis: Protein in mucous layer doesn’t function effectively, therefore mucous layer in respiratory tract becomes thick

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22
Q

Acid-fast or non acid fast more resistant

A

Acid-fast more resistant than non-acid fast

Mycobacterium TB - Resistant to aqueous baceticide bc mycolic acid layer

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23
Q

Endospores more resistant than vegetative

A

Endospores MOST resistant bacteria forms

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24
Q

Naked Viruses or Enveloped viruses more resistant

A

Envolope (if envelope is broken virus dies) viruses tend to be very easy to destroy (when outside the body)
Naked ones have thick protein coats which protects
Covid is a virus with a lipid envolope

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25
Cyst or trophozoite protozoans more resistant?
Cysts (surival structure for eukaryotic organisms) resistant to chlorine in water –Cryptosporidium cysts resistant to chlorine in water (spread by pigeons)
26
How quickly and at what rate do bacteria die off?
Bacteria die at constant rate The higher the conc. the longer it takes
27
Most resistant to least resistant forms of microorganisms
Prions Endospores of bacteri Mycobacteria Cysts of protozoa Vegetative protozoa Gram-negative bacteria Fungi AND fungal spores Viruses without envolopes Gram-positive bacteria Viruses with lipid envolopes
28
Most common physical control method
Heat
29
Why is moist heat more effective
Moist heat is more effective (steam at 100C more dangerous than oven at 325C) Moist heat Kills by coagulation of protein Boiling water does not actually reach as high heat
30
How does dry heat kill microbes
By oxidation (requires high temps for a longer time)
31
Approx. conditions for moist heat killing
Yeast is the lowest temperature for 5 mintes Molds is a higher temperature for 30 minutes Bacteria is the highest temperature for 10 minutes But endospores must be boiled for up to 20 hours to kill them
32
Does pasteurization change the tast
No
33
What bacteria is milk
Mycobacterium tuberculosis
34
3 levels of pastuerization
Low-temperature hold (LTH) 62.8°C for 30 minutes High-temperature short-term (HTST): 72°C for 15 seconds Ultra-high temperature (UHT): Process (5 sec cycle 74oC 140°C  74oC)
35
Autoclave
Saturated chamber with steam Raise temp to 121oC Apply pressure: 15 psi for 15 min Steam condenses on objects (121oC) Lower pressure to normal before opening chamber For surgical instruments, chamber is opened before pressure falls for solid objects (surgica instruments) to dry them instantly
36
3 forms of dry heat
Incineration Flaming Oven (170°C, 2 hours)
37
Two types of mechanical filtration
Depth filtering Membrane filters
38
How small do mechanical porte sizes go
.2 micrometers
39
What does bacteriostatic mean
most pathogens cannot grow i.e. refridgeration
40
A bacteria that is an exception to refridgeration being bacteriostatic
Listeria moncyotgenes
41
What is non ionizing radiation
UV light Non penetrating Can damage eyes, DNA Germicidal lamps for vaccine disinfection
42
What is ionizing radiation
Gamma rays, X ays, or high energy electron beams Cause mutation and death Low level ioninzing radiation > Used on speices certain meats and vegetables High energy radiation > used to sterilize medical supplies
43
How is "limiting water" applied to creating a bacteriostatic environment
Bacteria need water to survive High concentration of salt and sugar in solutions creates a hypertonic environment and thus bacteriostatic
44
Which kinds of microorganisms most resistant to desiccation and high salt conc.?
Molds and yeasts
45
How are disinfectants evaluated?
By the disc dilution method Inoculate bacteria on nutrient agar plates Place filter discs impregnated with disinfectant on plates and incubate Measure zones of inhibition (diameter) to determine effectiveness, larger diameter, greater effectiveness
46
What type of chemical disinfectant is used in lysol, toothpaste, and is an excellent skin disinfectant with a broad spectrum of activity?
Phenols
47
What disinfectant is used by desntists, having a low toxicity and thus safe for skin and mucous membranes
Chlorhexidine
48
What are the major examples of halogens
Iodine Chlorine Chlorine gas chloramines
49
Who was the pioneer of phenols
Joseph Lister
50
What is an Effectant chemical disinfectant against S. aureus
Hexachlorophene (phenol)
51
What "chemicals" are used for cleaning prior to surgeyr
Alcohols
52
widely used alchol disinfectant
Ethanol or isopropanol
53
Alcohol is most afffective at what level
70% aqueous solution
54
How do heavy metals affect microbes?
Denature proteins
55
What are examples of surfactants
Soaps, detergents - Clean but minimal disinfectant
56
Quat
Quaternary Ammonim compounds
57
What are quats commonly used in
Mouth wash Germicidal against most pathogens but not endospores
58
What kind of bacteria is mouthwash most effective against
Gram +
59
Hydrogen peroxide is classified as
An oxidizing agent Under the category of chemical sterilization
60
What do hospitals use as a chemical sterilant for bedding and mattresses
Ethylene oxide
61
Chlorine Dioxide
Used to sterilize building and contents of endospores or anthrax Also used in water treatment
62
How do oxidizing agents affect microbes
Interfere with metabolism
63
Ozone category and use
An oxidizing agent used as a primary water disinfectant
64
Why is a log curve used to graph bacteria death rates
Using a logarithmic scale makes it easier to visualize the population changes at late time points—the same data points that would otherwise be compressed down against the x-axis.
65
What can lead to C diff
Overuse of antibiotics
66
What do Healthcare facillities use for a higher level disinfectant than quats
Hypocholorite disinfectants
67
Disinfectant vs antiseptic
Disinfectant Use of chemicals (disinfectants) to kill or inhibit microorganisms that cause disease Does not kill all microorganisms Usually toxic and injurious to human tissues Antispectic: Chemicals used to treat or prevent infection of living tissues (still toxic)
68
Is heating food in the microwave microbial control?
NO
69
Does lightly heating food kill microbes?
No
70
Disinfectant used for skin?
No, that's antiseptic
71
Least susceptible microbes to sterilization
prions
72
Does dry heat OR pasteurization sterilize
Only dry heat sterilizes
73
Which of the following is a limitation of the autoclave?
cannot be used for heat labile materials
74
Which of the following treatments is the most effective for controlling microbial growth?
140°C for 4 seconds
75
Chlorhexidine use
for skin antisepsis but not for disinfection of environmental surfaces
76
microbes is known to be the most resistant to quaternary ammonium compounds?
Members of the genus Pseudomonas
77
Does alcohol sterilize
No
78
What bacteria is not effected by quats
Pseudomonas auriginos Can grow in quats
79
Semicritical instruments
Contact mucous Membrane and non intact skin
80
C. diff
Gram positive bacteria
81
Symptoms of C. diff
Digestive and colon problems
82
How must C. diff be disinfected
Quats cannot be used, but hypocolrite (Chlorine) based disinfectants used on surfaces that might come in contact with fecal matter
83
Spaulding rules
Critical (surgical instruments), semicritical, noncritical
84
Free radicals
Free floating electrons that damage membrane structure, DNA - Very reactive
85
What chemical keeps the steaks fresh
Sodium nitrate and nitrite
86
3 things contributing to HAI
Presence of microorganisms Immunocompromised individuals Chain of transmission (people, bedding, equipment)
87
What do surfactants do
Decrease surface tension or damage lipid membrane
88
Purpose of soaps
for cleaning but little disinfectant
89
Why is a 70% ethanol solution more effective than 100%
70% aqueous solutions more effective than 100% alcoholic solutions Pure ethanol evaporates very quickly Pure ethanol would cross the momebrane very quickly and react with proteins in the outer cytoplasm (TOO QUICKLY), forming a crust of dead proteins, protecting the cell from further ethanol exposure 70% ethanol reduces effectiveness, slows denaturing process, so no crust forms and more damage done to cell
90
Is ethanol effective against viruses?
Yes ALSO effective on lipid envelope and protein envelope (naked) viruses
91
How is mercury used medicinially
This heavy metal is found in eye drops and in contact lens solutions
92
What kinds of bacteria are quats effective against
G+ Not effective against endospores or mycobacteria
93
Ethyline oxide
(Penetrates deeper than liquid alcohol) Denatures protein High penetration power Sterilizes *microbes AND spores (Requires lengthy exposure time) Used ikn hospitals as chemical sterilant (beddings, mattressses)
94
Sodium nitrate and nitrite use for people
Keeping steaks fresh
95
Cleaning a toilet bowl would be considered __________
Disinfecting
96
Do autoclaves sterilize?
Yes
97
How could dairy products avoid requiring refrigeration?
Ultra-high-temperature (UHT) treatment
98
Which parts of the cell are the major targets of antimicrobial agents?
Proteins and cell membranes
99
why are microbial death curves are typically plotted logarithmically
Most microbial death occurs in the begining
100
Strategies for microbial growth control for heat labile items?
Filtration (for liquids not gases) Non Ionizing radiation Dessication Ossmotic pressure
101
How do phenyls afffect microbial growth>
Phenolics exert antimicrobial activity by injuring lipid-containing plasma membranes, which causes the cellular components to leak out of the cell
102
What phase in bacterial growth is penicillin most effective
Log
103
Most effective form of microbial growth control
UHT (5 sec cycle 74oC 140°C  74oC)
104

BIO233 (18 decks)

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