chapter 9 study questions Flashcards
____________ is the destruction of most microbes using chemicals on a living surface such as the skin.
antisepsis/degermation
a process that completely removes all viable microorganisms, including viruses, from an object or habitat is referred to as __________
sterilization
an object that is free of all viable microorganisms and all viruses is described as ________
sterile
True or False:
There are several degrees of sterility, based on the destruction of endospores.
FALSE
The use of a physical process or a chemical to destroy vegetative pathogens but not bacterial endospores, usually on inanimate surfaces, is called _________.
disinfection
The general term used for the reduction of the microbial load in order to lower the possibility of infection or spoilage is __________.
Decontamination or sanitization
Reducing the number of microbes on human skin through a combination of mechanical friction and the application of chemicals is called _______.
degermation
which disease-causing agent is resistant to both heat and chemicals?
prions
disinfection destroys __________
only vegetative bacterial cells
A cleansing technique, often using soaps and detergents, that mechanically removes microorganisms as well as other debris to reduce contamination to safe levels is called __________.
decontamination
two examples of sterilization techniques
autoclaving - pressurized steam
ionizing radiation
The physical removal of surface oils, debris, and soil from skin to reduce the microbial load is called _______
degermation
Prions are resistant to _______ and _______.
resistant to heat and chemicals
A chemical that can kill fungal spores, hyphae, and yeasts is called a _______.
fungicide
Virucides ______ viruses
inactivate
The mechanical removal of most microbes from inanimate or animate surfaces is called ______.
-> Hint: inanimate and animate
decontamination or sanitization
what agent specifically destroys bacterial endospores?
sporicide
non-endospore forming pathogenic microorganisms can be killed with a _________
germicide or microbicide
where microorganisms are growing in blood or other tissues is referred to as _____
sepsis
devices that come into contact with mucosal membranes are called _______
semicritical
items not in touch with patients or only in touch with intact skin ie. blood pressure cuffs
noncritical
devices that are expected to come into contact with sterile tissues ie. artificial hip
critical
characterized by the stopping of call metabolic activity of a cell
death
what is a chemical agent that kills microorganisms but is not effective against bacterial endospores
germicide
what items are considered critical for sterilization?
artificial hip and syringe needle
NOT crutches (noncritical), stethoscope (noncritical), or endoscopy tube (semi critical)
most common physical agent to control microbes is
heat
; moist and dry heat
higher temps are usually _______, whereas lower temps are usually _______.
microbicidal
microbistatic
_____ are chemical agents that kill non-endospore forming pathogens
germicides
dry heat occurs in the forms of _______ and _______.
an open flame and hot air oven
___ heat requires longer exposure times and higher temps than _____ heat.
dry
moist
the most lethal effect of moist heat is the coagulation and denaturation of ________, which quickly and permanently halts cellular metabolism.
proteins
the most prominent antimicrobial physical agent is _________.
heat
what factors must be considered in order to adequately sterilize using heat?
presence of water
temp
length of exposure
NOT pH of enviro
Dry heat __________ the cell, removing the water necessary for metabolic reactions, and it also _________ proteins.
dehydrates or desiccates
denatures or unfolds
boiling water and steam are examples of ________ heat.
moist
Which of the following are relatively resistant to heat? Select all that apply.
a. vegetative cells
b. fungi
c. endospores
d. viruses
c and d
*vegetative cells have low resistance to heat
How does microbial control via moist heat differ from control via dry heat?
moist heat requires shorter exposure times and lower temps
The shortest length of time required to skill all test microbes at a specified temperature is referred to as :
thermal death time
Moist heat has the most significant effects on cellular __________.
proteins
The lowest temperature required to skill all microbes in a sample in 10 minutes is the :
thermal death point
**NOT TO BE MISTAKEN WITH THERMAL DEATH TIME
When a loop is flamed in a microbiology lab, dry heat:
oxidizes cells, burning them to ashes
Incineration is a form of ________ heat.
dry
Which two variables contribute to the thermal death TIME?
heat and time
Boiling water can be an effective means of ________.
disinfection
A technique in which heat is applied to liquids to kill potential agents of infection and spoilage is ________.
pasteurization
The goal of regular pasteurization methods is the ___________ of the liquid.
disinfection
which method of pasteurization uses a lower temperature for a longer period of time?
batch method,, NOT flash method
boiling water can be an effective means of _________ and _________ in the clinic and home.
sanitization and disinfection
moist heat temp range
60-135 degrees C
dry heat temp range
160 to several thousand degrees C
incineration, dry heat, is a form of ___________.
sterilization
to dry thoroughly
desiccation
a method for preserving organisms, by freezing and then drying them
lyophilization
types of radiation suitable for microbial control
gamma rays, X rays, and ultraviolet radiation
two types of ionizing radiation that sterilize
gamma rays and X rays
Nonionizing radiation example (not sterile)
UV rays
an effective method to remove microbes from air and liquids; straining
filtration
adding large amounts of salt or sugar to foods to create a hypertonic environment for bacteria in the foods, causing plasmolysis and making it impossible for the bacteria to multiply; method of microbial control
osmotic pressure
what microbes are not usually destroyed or inactivated with regular pasteurization methods?
heat-resistant microbes and endospores
**viruses are usually inactivated with p treatments
substances like oils or waxes are not effectively sterilized in an autoclave b/c they
repel moisture
give two examples of substances not suited for sterilization in an autoclave
powders and oils
UV radiation is usually used for ____________.
disinfection
what unit is radiation measured in?
Grays
the use of sugar or salt to preserve food creates a __________ environment for the bacteria in the foods.
hypertonic
what are tinctures?
solutions dissolved in pure alcohol or alcohol-water mixtures
what do high level germicides do?
kill endospores and sterilize
what do intermediate level germicides do?
kill fungal (but not bacterial) spores, and kill resistant pathogens such as the bacterium that causes tuberculosis, and viruses
what do low level germicides do?
eliminate only vegetative bacteria, vegetative fungal cells, and some viruses
three examples of organisms that chlorine destructs
Mycobacterium tuberculosis
Entamoeba cysts
Hep A virus
list three organisms that ethyl alcohol destructs
S. aureus
E. coli
Poliovirus
list three organisms that hydrogen peroxide destructs?
S. aureus
Neisseria gonorrhoeae
Herpes simplex virus
a desirable characteristic of a germicide is _______ spectrum action
broad
UV radiation is effective at disinfecting which types of materials?
solid surfaces, air, and liquids
Ethylene oxide typically kills microbes by
disrupting enzyme function
blocking DNA replication
—>can disinfect plastic materials, delicate instruments, used to sterilize syringes, surgical supplies, and medical devices that are prepackages
which chemical is valuable for sterilization of heat-sensitive objects such as plastics, surgical and diagnostic appliances, and spices, but is more toxic than other related gases?
ethylene oxide
which of the following compounds are commonly used as gaseous sterilants or disinfectants?
chlorine dioxide
ethylene oxide
Chemical Group: Halogens
Chlorine
can slowly skill endospores and all other microbes
liquid/gaseous form
disinfects drinking water, sewage and waste water, used in HC to treat wounds and disinfect bedding instruments, sanitize food equipment
—> denatures enzymes permanently and suspends metabolic reactions
Chemical Group: Halogens
Iodine
sterilant
- interferes with variety of metabolic functions
- interferes with hydrogen and disulfide bonding of proteins
—> disinfects plastic and rubber instruments, cutting blades, prepares skin for surgery, treats burns and disinfects
Oxidizing agents:
hydrogen peroxide and peracetic acid
sterilant
-oxygen forms free radicals which are highly toxic and reactive to cells
—>skin and wound cleansing, mouth washing, bedsore care, treats infections caused by anaerobic bacterial; used in low temp sterilizing cabinets for delicate instruments
**sporicidal only in HIGH concentrations
Aldehydes
sterilant
-irreversibly disrupt the activity of enzymes and other proteins within the cells
—> kills rapidly and is broad spectrum; sterilizes equipment, scopes, kidney dialysis machines, dental instruments
Phenol (carbolic acid)
NOT A STERILANT
kills some bacteria, viruses, fungi
- disrupt cell walls and membrane proteins (high concentration)
- inactivate certain critical enzyme functions (low concentrations)
—>disinfectants (drains, cesspools, animal quarters)
**many are toxic and dangerous to use as antiseptics
Chlorhexidine
NOT A STERILANT
kills most bacteria, viruses, and fungi
-targets bacterial membranes where selective permeability is lost, bacterial cell walls, proteins (denaturation)
—> hand scrubs, prepping skin for surgery, obstetric antiseptic
detergents ____________ the cytoplasmic membrane
disrupt
Heavy metal compounds exert microbial effects by __________ onto functional groups of proteins and _________ them.
binding
inactivating
what are some desirable qualities in a germicide?
broad spectrum
rapid action
not corrosive and non-staining
solubility in a solvent
Glutaraldehyde affects what type of macromolecules?
Hint: what do aldehydes disrupt?
they disrupt and denature proteins and enzymes
Organic substances bearing a -CHO functional group on the terminal carbon are called?
aldehydes
Heavy metal germicides come in which of the following forms?
a. aqueous solutions
b. solid capsules
c. ointments
aqueous solutions
ointments
gases that are commonly used as sterilant or disinfectants are ethylene oxide and __________ dioxide
chlorine
Heavy metals that are still used in germicidal preparations are mercury and __________
silver / Ag
True or False:
heavy metals may be used for topical germicides and ointments
Hint: think of Sujata’s story about silver and skin color
True - silver nitrate is a component of topical ointments
Quats are rated as ______________ disinfectants in the clinical setting
low-level
True or False:
Tinctures and ointments are two types of heavy metal germicides.
True, there are also aqueous solutions too
soaps and quats are commonly used for
sanitization of the home and food prep equipment
skin cleansing
disinfection of restrooms
Cationic detergents typically work by
disrupting the cell membrane
although they do have some drawbacks, heavy metals are used for:
prevention of infection
preservatives
skin cleansing
controlling microbial growth on objects
what type of macromolecule is affected by heavy metals?
proteins, by inactivating them
which type of detergents are more effective?
cationic
hydrogen peroxide is commonly used for
sterilization of diagnostic instruments
skin and wound cleansing
__________ typically kills microbes by producing toxic free radicals
hydrogen peroxide
True or False: household cleaners are often alcohol based
false, alcohol is most commonly used as a degerming agent for the skin
alcohols usually affect microbes by
disrupting cell surface tension
disrupting cell membrane
which two alcohols are effective in microbial control?
ethyl
isopropyl
alcohols are effective against
most bacteria, fungi, and enveloped viruses
chlorhexidine solutions are commonly used for
antisepsis of the skin
–> medical moment example with mouthwash to prevent microbial build up on mouth tube going into lungs (infection possibility)
chlorhexidine typically kills microbes by
disrupting the cell wall
disrupting cell membrane
denaturing proteins
true or false: routine skin antisepsis often is completed using phenolics
false, it can be toxic to the skin
what is the mode of action of phenolics?
disruption of cell walls or membranes
also disrupt enzymatic systems (denatures metabolic enzymes)`
phenol is now limited to its used in
drains, cesspools, and animal quarters
phenolics are
microbicidal
complexes of iodine and alcohol are called
iodophors
iodine compounds are typically used for
disinfection of medical equipment
antisepsis of skin
tx of skin wounds
iodine compounds typically kill microbes by
denaturing proteins
