Control of Microbial Growth Flashcards

1
Q

what is sterilization?

A

destruction or removal of all viable organisms

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2
Q

what is disinfection?

A

killing, inhibition, or removal of disease causing organisms`

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3
Q

what are disinfectants?

A

agents, usually chemical, used for disinfection on inanimate objects (typically)

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4
Q

what is sanitization?

A

reduction of the microbial population to levels deemed safe based on public health standards

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5
Q

what is antisepsis?

A

prevention of infection of living tissue by microorganisms

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6
Q

what are antiseptics?

A

chemical agents that kill or inhibit growth of microorganisms when applied to tissue

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7
Q

how is chemo used as antimicrobial agents?

A

use of chemicals to kill or inhibit growth of microorganisms within host tissue

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8
Q

what do -cidal agents do?

A

kills bacteria

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9
Q

what do -cidal agents do?

A

kills bacteria

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10
Q

what are examples of cidal agents?

A

bactericides, fungicides, and viricides

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11
Q

what does -static indicate?

A

a growth inhibiting agent

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12
Q

what is the pattern of microbial death?

A

microorganisms are not killed instantly
population death typically occurs exponentially
is a measure of an agents killing efficiency
make sure that viable but noncultural cells are dead

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13
Q

what is decimal reduction time?

A

the time it takes to kill 90% of cells

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14
Q

what does filtration do?

A

reduces microbial population or sterilizes solutions of heat-sensitive materials by removing microorganisms
also used to reduce microbial populations in the air

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15
Q

what are membrane filters?

A

porous membranes with defined pore sizes that remove microorganisms primarily by physical screening

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16
Q

what are some examples of air filters?

A

surgical masks
high-efiicienctb particulate air (HEPA) filters

17
Q

what are some examples of using moist heat as control?

A

pasteurization
boiling
steam sterilization

18
Q

what does moist heat destroy?

A

viruses, fungi, bacteria
NOT endospores

19
Q

how does moist heat work?

A

degrades nucleic acids, denatures proteins, and disrupts membranes

20
Q

steam sterilization

A

carried out above 100 degrees C which requires saturated steam under pressure
effective against all types of microbes

21
Q

pasteurization

A

controlled heating at temperature well below boiling
used for milk, beer, and other beverages
process does not sterilize but kills pathogens present and slows spoilage y reducing the total load of organisms present

22
Q

dry heat sterilization

A

less effective than moist heat sterilization, requires higher temperatures and longer exposure time
oxidizes cell constituents and denatures proteins
does not corrode glasswares and metal instruments as moist heat does

23
Q

what is an example of dry heat sterilization?

A

flaming out inoculating loops

24
Q

ultraviolet radiation

A

260 wavelength is most bactericidal
causes thymine dimers preventing replication and transcription
limited to surface sterilization because it doesn’t penetrate glass, dirt films, water, or other substances
used for water treatment

25
ionizing radiation
gamma radiation penetrates deep into objects destroys bacterial endospores; not always effective against viruses used for sterilization and pasteurization of antibiotics, hormones, sutures, plastic disposable supplies, and food
26
what has overuse of antiseptics caused?
selection for resistant bacteria
27
phenolics
commonly used as laboratory and hospital disinfectants act by denaturing proteins and disrupting cell membranes tuberculocidal, effective in presence of organic material, and long lasting disagreeable odor and can cause skin irritations
28
alcohols
among the most widely used disinfectants, antiseptics, and sanitizers bactericidal, fungicidal, but not sporicidal can inactivate some viruses denature proteins and possibly dissolve membrane lipids
29
halogens (iodine)
skin antiseptic oxidizes cell constituents and iodinates proteins may kill endospores at high concentrations skin damage, staining, and allergies may be a problem
30
what is iodophor?
iodine complexed with organic carrier released slowly to minimize skin burns
31
halogens (chlorine)
oxidizes cell constituents important in disinfection of water supplies and swimming pools, used in dairy and food industries, effective household disinfectant destroys vegetative bacteria and fungi gas is sporicidal
32
heavy metals
mercury, silver, arsenic, zinc, copper effective but usually toxic combine with and inactivate proteins; may precipitate cell proteins
33
quaternary ammonium compounds
detergents that have broad spectrum antimicrobial activity and are effective disinfectants amphipathic organic cleansing agents
34
what are cationic detergents?
effective disinfectants that kill most bacteria, but not M. tuberculosis or endospores stable and non-toxic, inactivate by hard water and soap
35
aldehydes
commonly used agents are formaldehyde and glutaraldehyde highly reactive molecules sporicidal and can be used as chemical sterilants
36
sterilizing gases
used to sterilize heat-sensitive materials microbicidal and sporicidal ethylene oxide sterilization is carried out in equipment resembling an autoclave vaporized hydrogen peroxide can also be used
37
what are some examples of natural control mechanisms?
predation by Bdellovibrio viral-mediated lysis using pathogen specific bacteriophage lysins toxin-mediated killing using bacteriocins
38
what are the conditions that influence the effectiveness of antimicrobial agents?
population size -larger=longer to kill population composition concentration or intensity of an antimicrobial agent -higher concentrations kill faster contact time -longer exposure=more killed temperature -higher temps=enhanced chem activity
39
how does local environment affect the effectiveness of antimicrobial activity?
pH, viscosity, concentration of organic matter, etc., van profoundly impact effectiveness organisms in biofilms are less susceptible