CH 5 - Microbiology
The common parameters used in autoclaving are __________
121 degrees C at 15 psi for 15 min
Biosafety levels are specific combinations of work practices, safety equipment, and facilities required to work with microorganisms. These precautionary guidelines are established by the _______
CDC
Biosafety levels are specific combinations of work practices, safety equipment, and facilities required to work with microorganisms. These precautionary guidelines are established by the ________
CDC
True or False: Methods used to control microbial growth are not important in microbiology labs since they routinely work with many types of microorganisms anyway
False
True or False: There is a standard antimicrobial procedure available from the CDC that can be used for all different microorganisms under any condition
False
Consider the use of low temperature storage for the preservation of food. Which of the following are accurate statements?
Psychrotrophic and some psychrophilic microorganisms can grow at refrigeration temperatures Refrigeration inhibits the growth of many pathogens and spoilage microorganisms by slowing or stopping critical enzyme reactions
True or False: Although endospores of certain thermophiles can survive the commercial canning process, these are rarely a concern
True
In addition to destroying C. botulinum endospores, commercial canning also destroys _____.
all other organisms that grow under normal storage conditions
In addition to destroying C. botulinum endospores, commercial canning also destroys _________
all other organisms that grow under normal storage conditions
A sterile object is free of ________
all viable microorganisms and viruses
______ are chemicals used to decrease the number of microbes on living tissues, whereas _________ are used to destroy microbes on inanimate (non living) objects
antiseptics disinfectants or germicides
It is often difficult to choose which germicide to use because often the most effective options _________
are not the safest
Germicide chemicals __________
are often poorly understood with regards to mechanisms of action usually react irreversibly with proteins, DNA, cytoplasmic membranes or viral envelopes
The precautionary guidelines established by the CDC for laboratories working with microorganisms are known as ________________ or BSLs and range from BSL-1 to BSL-4
biosafety levels
The precautionary guidelines established by the CDC for laboratories working with microorganisms are known as _________________ or BSLs and range from BSL-1 to BSL-4
biosafety levels
Adding sorbic, propionic, and benzoic acid to foods affects ______ of microbes.
cell membrane function
Which of the following are effects of ionizing radiation on food products?
changes in flavor of some foods killing of bacterial pathogens
Choosing the correct antimicrobial procedure depends on many factors including _________
composition of item environmental conditions type and number of microbes
A surgical scalpel is rated as a _______ instrument because it penetrates skin and mucous membranes and therefore must be sterile
critical
A surgical scalpel is rated as a ________ instrument because it penetrates skin and mucous membranes and therefore must be sterile
critical
Treating a surface by washing or using disinfectants in order to reduce the number of pathogens on that surface to a safe level is called
decontamination
Adding large amounts of salt and sugar to foods _____.
dehydrates microbes and prevents their growth
Which of the following are often referred to as germicides?
disinfectants
Potentially harmful chemicals referred to as ________ by products (DBPs) form when chlorine and similar substances react with chemicals in the water
disinfection
Potentially harmful chemicals referred to as __________ by products (DBPs) form when chlorine and similar substances react with chemicals in the water
disinfection
The process of ______ involves the use of antimicrobial chemicals on a surface. As opposed to sterilization, this process leaves some viable microorganisms
disinfection
The process that eliminates most or all pathogens on or in a material is __________
disinfection
To achieve equivalent microbial killing, moist heat requires ____________ exposure times and higher temperatures than _____ heat
dry moist
Cases of salmonellosis have been traced to dried eggs. This demonstrates that ________
drying is not a reliable way to kill all microbes
The most highly resistant microbial structure is the bacterial _____.
endospore
A retort is an industrial sized autoclave that ensures that __________ are destroyed
endospores of Clostridium botulinum
True or False: Choosing which germicide to use is not that complicated since we only consider how effective it is against the target microbes
false
True or False: There is a standard antimicrobial procedure available from the CDC that can be used for all different microorganisms under any condition
false
True or False: There is no risk of food poisoning with dried food since drying kills all microorganisms associated with the food
false
True or false: ionizing radiation is not an effective method of controlling microbes in food products
false
True or false: microwaves always cook foods and kill microbes effectively
false
_______ is a physical means used for destroying or removing microorganisms
filtration
__________ is a physical means used for destroying or removing microorganisms
filtration
A common dry heat sterilization method used in the microbiology laboratory is:
flaming the inoculating loop
_______ are chemicals used to destroy most pathogens on or in inanimate objects
germicides
It is important to minimize the number of pathogens in health-care settings due to the risk of ________ associated infections (HAIs)
health-care, hospital, or healthcare
It is important to minimize the number of pathogens in health-care settings due to the risk of ________ associated infections (HAIs)
healthcare
Although generally less reliable than heat, germicidal chemicals are especially useful for treating _________
heat sensitive items large surfaces
Autoclaves can be used for flash sterilization of surgical instruments in the operating room. In this case, autoclaving occurs at a _________ temperature for a _________ time
higher shorter
Autoclaves can be used for flash sterilization of surgical instruments in the operating room. In this case, autoclaving occurs at a _____________ temperature for a _________ time
higher shorter
Salting and drying decrease the availability of water in food, resulting in an environment that is ______ relative to microbes, thereby preventing their growth.
hypertonic
________ is the destruction of microbes by subjecting them to extremes of dry heat, reducing them to ashes
incineration
__________ is the destruction of microbes by subjecting them to extremes of dry heat, reducing them to ashes
incineration
What are the effects of increasing the pressure of water in an autoclave?
increases the temperature at which steam forms increases the boiling point of water
What type of radiation has enough energy to remove electrons from atoms, thereby destroying DNA and damaging cytoplasmic membranes?
ionizing
________ provides an alternative to heat for sterilization and disinfection, but the process damages some types of plastics
irradiation
___________ provides an alternative to heat for sterilization and disinfection, but the process damages some types of plastics
irradiation
Adding preservatives such as benzoic acid to food is important because ______.
it inhibits growth of many bacteria and mold
What is the major disadvantage of using dry heat instead moist heat to kill microbes?
longer time requirement
A solution of sodium hypochlorite is more effective against bacteria at ___________ pH
low
A solution of sodium is most effective against bacteria at __________ pH
low
Freeze drying or ________ is used to preserve coffee, milk, meats and vegetables
lypophilization
The process of preserving foods by rapid freezing followed by drying in a vacuum is called __________
lypophilization
Soap generally does not destroy most microbes, but it aids in their _____.
mechanical removal
Washing hands with plain soap and water works by _______ removing microbes
mechanically
Paper-thin membrane filters called ____ contain pore sizes so small they will trap microbes from liquids as they pass through
microfilters
A concentrated culture of cells will take _____ time to kill than a dilute culture of the same organism.
more
Household bleach applied at 55C is ________ effective in killing bacteria than if it were applied at 50
more
A _______ instrument is one that should only come into contact with intact skin
non critical
A _________ instrument is one that should only come into contact with intact skin
non critical instrument
Many germicides lose their effectiveness in the presence of
organic matter
A brief heat treatment that reduces the number of spoilage of organisms and destroys pathogens is called __________
pasteurization
A brief heat treatment used to make foods and beverages safe for consumption is ________
pasteurization
Brief heat treatment that reduces the number of spoilage organisms and destroys disease-causing microbes
pasteurization
Which of the following is a brief heat treatment used to prevent spoilage of wine without changing its flavor?
pasteurization
Water treatment facilities work to ensure that drinking water is devoid of __________
pathogenic microbes
Water treatment facilities work to ensure that drinking water is devoid of ____________
pathogenic microbes
Minimizing the numbers of microbes in hospital settings and other health-care facilities is important because _____. (3)
pathogens are more likely to be found in health-care facilities hospitalized patients are often more susceptible to infection of the danger of acquiring a health-care associated infection
Minimizing the numbers of microbes in hospital settings and other health-care facilities is important because _________
pathogens are more likely to be found in health-care facilities hospitalized patients are often more susceptible to infection of the danger of acquiring a health-care associated infection
A high-solute environment damages microbial cells by causing _____.
plasmolysis
The act of delaying spoilage is _____.
preservation
process of delaying spoilage of foods and other perishable products
preservation
process of delaying spoilage of perishable products
preservation
Chemicals called __________ are used to prevent the growth of undesirable organisms in foods and beverages
preservatives
Which of the following use moist heat to destroy microbes?
pressurized steam boiling pasteurization
When boiling of pasteurizing a sample, microorganism are destroyed because their __________
proteins are irreversibly denatured
When boiling or pasteurizing a sample, microorganisms are destroyed because their _____.
proteins are irreversibly denatured
Which four of the following microbial groups are the most resistant to chemical control methods?
protozoan cysts and oocysts bacterial endospores Mycobacterium species non-enveloped viruses
Which four of the following microbial groups are the most resistant to chemical control methods?
protozoan cysts and oocysts bacterial endospores Mycobacterium species non-enveloped viruses
Ionizing radiation causes indirect tissue damage by reacting with O2 to produce __________ oxygen _____________ (ROS)
reactive species
What are the main limitations of using UV radiation?
safety of use poor penetration
A process that substantially reduces the number of microbes to meet accepted health standards, but doesn't indicate any specific level of control, is known as _______
sanitation
A process that substantially reduces the number of microbes to meet accepted health standards, but doesn't indicate any specific level of control, is known as _________
sanitation
Endoscopy and endotracheal tubes are considered _____ instruments, since they come into CONTACT with mucous membranes.
semi critical
Medical instruments are classified into three categories according to their risk for transmitting diseases. These are: critical instruments, __________________ and __________________
semi critical instruments noncritical instruments
Endoscopy and endotracheal tubes are considered _____ instruments, since they come into CONTACT with mucous membranes.
semi-critical
Medical instruments are classified into three categories according to their risk for transmitting pathogens. These are: critical instruments, __________ and ________________
semi-critical instruments non-critical instruments
The main effect of low temperature storage is to ______.
slow the activity of microbes
Following treatment to remove all viable microorganisms, including viruses, an object is considered to be ________
sterile
The process of destroying or removing all microbes through physical or chemical processes is _________
sterilization
________ is the removal or destruction of all microorganisms and viruses on or in a product
sterilization
Prior to being used to cultures, media is ________ to ensure that the cultures remain pure
sterilized
Prior to being used to grow cultures, media is _____ to ensure that the cultures remain pure.
sterilized
Which of the following are used as preservatives by creating an environment that will draw water out of cells, dehydrating them?
sugar salt
UV radiation is used extensively to destroy microbes in _________
the air drinking water
Where would it be acceptable to risk using an effective germicide that is somewhat toxic to humans?
the hospital
The effectiveness of germicidal chemicals depends upon ________
the presence of organic matter the concentration used
It is important to destroy all endospores of Clostridium botulinum in commercial canning because ________
the spores can germinate in canned foods and vegetative cells can produce botulinum toxin
it is important to destroy all endospores of Clostridium botulinum in commercial canning because _________
the spores can germinate in canned foods and vegetative cells can produce botulinum toxin
Disinfectants are normally only used on inanimate objects because _________
they are harmful to living tissues
Microwave ovens are not reliable for killing microbes in food because ________
they often heat food unevenly
The number of cells in a culture will most influence the ________ necessary to kill them.
time
True or False: germicides are generally somewhat toxic to humans and the environment
true
Choosing the correct antimicrobial procedure depends on many factors including ________
type and number of microbes composition of item environmental conditions
Choosing the correct antimicrobial procedure depends on many factors including _________
type and number of microbes composition of item environmental conditions
Which of the following are physical ways to remove or destroy microbes?
ultraviolet radiation filtration autoclaving incineration
Germicide chemicals __________
usually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes are often poorly understood with regards to mechanisms of action
As the pressure in an autoclave increases, the boiling point of _____ also increase, as does the temperature at which _____ forms.
water steam
When would it be a better idea to use a filter rather than an autoclave to sterilize a solution?
when the solution is heat sensitive