microbiology ch 7 Flashcards
What is sepsis?
Bacterial contamination
What is asepsis?
Absence of significant contamination
What do aseptic surgery techniques do?
Prevent the microbial contamination of wounds
This is a term for bacterial contamination
Sepsis
This is the absence of significant contamination
Asepsis
These prevent the microbial contamination of wounds
Aseptic surgery techniques
What is sterilization?
Removing and destroying all microbial life
What is an example of commercial sterilization?
Killing Clostridium botulinum endospores from canned goods
What is disinfection?
Destroying harmful microorganisms
What is antisepsis?
Destroying harmful microorganisms from living tissue
What is degerming?
The mechanical removal of microbes from a limited area
What is sanitization?
Lowering microbial counts to safe levels
What is biocide (germicide)?
Treatment that kills microbes
What is bacteriostasis?
Inhibiting microbe growth
Does bacteriostasis kill microbes?
No
This is removing and destroying all microbial life
Sterilization
An example of this is the killing of Clostridium botulinum endospores from canned goods
Commercial sterilization
This is destroying harmful microorganisms
Disinfection
This is destroying harmful microorganisms from living tissue
Antisepsis
This is the mechanical removal of microbes from a limited area
Degerming
This is lowering microbial counts to safe levels on eating utensils
Sanitization
These are treatments that kill microbes
Germicides (biocides)
This is the inhibition, but not killing, of microbes
Bacteriostasis
What are four factors in the effectiveness of microbe control?
Number of microbes; environment; exposure time; microbial characteristics
Do most microbial controls work better in cold conditions?
No
Do resistant microbes/endospores require more time to kill?
Yes
The number of microbes, environmental conditions, time of exposure, and microbial characteristics all influence this
Effectiveness of microbial control efforts
What are the 3 main ways of killing/inhibiting microbes?
Altering membrane permeability; damaging proteins (enzymes); damaging nucleic acids
How does altering membrane permeability kill/inhibit microbes?
Damage to lipids/proteins of plasma membrane causes cellular contents to leak and interferes with cell growth
How does damaging a microbes’ proteins/enzymes kill/inhibit it?
Chemicals disrupt the bonds that maintain the three-dimensional shape of proteins/enzymes
How does damaging nucleic acids kill/inhibit microbes?
Damage from heat, radiation, or chemicals can affect cell’s ability to replicate and carry out normal metabolic functions
What does heat do to enzymes?
Denatures them
What is the thermal death point (TDP)?
The lowest temperature at which all cells in a liquid culture are killed in 10 minutes
What is the thermal death time (TDT)?
The minimum time for all bacteria in a liquid culture to be killed at a particular temperature
This denatures enzymes
Heat
This is the lowest temperature at which all cells in a liquid culture are killed in 10 minutes
Thermal death point (TDP)
This is the minimum time for all bacteria in a liquid culture to be killed at a particular temperature
Thermal death time (TDT)
What is decimal reduction time (DRT)?
Time to kill 90% of a specific population of bacteria at a given temperature
This is the time it takes to kill 90% of a specific population of bacteria at a given temperature
Decimal reduction time (DRT)
What does moist heat sterilization do to proteins?
Denatures and coagulates
What are two types of moist heat sterilization?
Boiling and free-flowing steam
This type of sterilization denatures and coagulates proteins
Moist heat sterilization
Boiling and free-flowing steam are two methods of this type of sterilization
Moist heat sterilization
What does an autoclave use to sterilize equipment?
Steam under pressure
What are typical autoclave conditions?
121 degrees at 15 psi for 15 minutes
Does an autoclave kill endospores?
Yes
What must steam do in an autoclave to be effective?
Contact the item’s surface
What are used to indicate sterility when using an autoclave?
Test strips
Do large containers require shorter sterilization times in an autoclave?
No
What sterilization method uses steam under pressure?
Autoclave
In this sterilization method, pressurized steam kills all organisms and endospores
Autoclave
This sterilization method uses test strips to indicate sterility
Autoclave
In this sterilization method, smaller containers require shorter sterilization times
Autoclave
What does pasteurization involve?
High heat for a short time
What is a typical set of conditions for pasteurization?
72 degrees for 15 seconds
What organisms can survive high heat?
Thermoduric
This sterilization method uses high heat for short intervals to reduce spoilage organisms and pathogens
High-temperature short time (HTST) pasteurization
Thermoduric organisms can survive this
High heat
What are three methods of dry heat sterilization?
Flaming, incineration, and hot-air sterilization
What kills microbes in dry heat sterilization?
Oxidation
Flaming, incineration, and hot-air sterilization are three forms of this type of sterilization
Dry heat sterilization
This type of sterilization kills microbes by oxidation
Dry heat sterilization
This type of sterilization passes substances through a screenlike material
Filtration
What type of materials is the filtration method of sterilization used for?
Heat-sensitive materials
What size of microbes do high-efficiency particular air (HEPA) filters remove?
> 0.3 um in diameter
What size of microbes do membrane filters remove?
> 0.22 um
What are the smallest pore sizes available of microbe filtration?
0.01 um
What can 0.01 um filtration remove?
Viruses and large proteins
This sterilization method is used for heat-sensitive materials
Filtration
These can remove microbes >0.3 um in diameter
High-efficiency particular air (HEPA) filters
These can remove microbes >0.22 um in diameter
Membrane filters
Viruses and large proteins can be filtered through this pore size
0.01 um
What are three methods of low temperature microbial control?
Refrigeration, deep-freezing, and lyophilization (freeze-drying)
How does high pressure control microbes?
By denaturing proteins
How does desiccation control microbes?
The absence of water prevents metabolism
How does osmotic pressure control microbes?
Creates a hypertonic environment and plasmolysis
What effect does low temperature have on microbes?
Bacteriostatic effect
Which physical method of microbial control denatures proteins?
High pressure
Which physical method of microbial control prevents metabolism?
Desiccation
Which physical method of microbial control uses high concentrations of salts/sugars?
Osmotic pressure
Which physical method of microbial control creates a hypertonic environment and causes plasmolysis?
Osmotic pressure
What are three forms of radiation as microbial control?
Ionizing radiation, nonionizing radiation, and microwaves
How does ionizing radiation kill microbes?
Creates reactive hydroxyl radicals and causes lethal mutations in DNA
How does nonionizing radiation kill microbes?
By creating thymine dimers in DNA
How do microwaves kill microbes?
By heat
This method of radiation microbe control damages DNA by causing lethal mutations
Ionizing radiation
What are three types of ionizing radiation used to kill microbes?
X-rays, gamma rays, electron beams
This method of radiation microbe control damages DNA by creating thymine dimers
Nonionizing radiation
What type of nonionizing radiation is used to kill microbes?
Ultraviolet (260nm)
This type of radiation microbe control kills by heat and is not especially antimicrobial
Microwave
What are four factors in effective disinfection?
Concentration of disinfectant, presence of organic matter, pH, and time
How does organic matter affect disinfection?
By interfering with the mechanism of action
Does pH have a great effect on disinfectant’s activity?
Yes
Is effectiveness of a disinfectant unrelated to its concentration?
No
Can organic material interfere with a disinfectant?
Yes
Is time a factor in disinfection?
Yes
What are two methods to evaluate a disinfectant?
Use-dilution test and disk-diffusion method
What does the use-dilution test for evaluating disinfectant involve?
Dipping metal cylinders in test bacteria and drying, then placing in disinfectant and transferring to culture media
In this disinfectant evaluation method, metal cylinders are dipped in bacteria then disinfected then transferred to culture media to determine whether bacteria survived treatment
Use-dilution test
What does the disk-diffusion method of evaluating disinfectant involve?
Soaking filter paper disks in a chemical and placing on a culture
In the disk-diffusion of evaluating disinfectant, what indicates an effective disinfectant?
Zone of inhibition around filter paper disk
What does the disk-diffusion method evaluate?
The efficacy of chemical disinfecting agents
In this method of disinfectant evaluation, filter paper disk are soaked in a chemical and placed on a culture medium
Disk-diffusion method
In the disk-diffusion method of disinfectant evaluation, does a smaller zone of inhibition indicate a more effective disinfectant?
No
How do phenols and phenolics control microbes?
By injuring lipids of plasma membranes, causing leakage
These chemicals kill microbes by injuring the plasma membrane and causing leakage
Phenols and phenolics
How are bisphenols structured?
Two phenol groups connected by a bridge
What are two examples of bisphenols?
Hexachlorophene and triclosan
How do bisphenols work?
By disrupting plasma membranes
These chemical disinfectants contain two phenol groups connected by a bridge
Bisphenols
Hexachlorophene and triclosan are two examples of this group of chemical disinfectants
Bisphenols
How do biguanides work?
By disrupting plasma membranes, especially in gram-positive bacteria
What are biguanides used in?
Surgical hand scrubs
What is an example of a biguanide?
Chlorhexidine
These chemical disinfectants include chlorhexidine and are used in surgical hand scrubs
Biguanides
This group of chemical disinfectants disrupts plasma membranes, and is especially effective against gram-positive bacteria
Biguanides
What are essential oils?
Mixtures of hydrocarbons extracted from plants
What have essential oils been used for historically?
Traditional medicine and food preservation
What is the microbial action of essential oils due to?
Phenolic and terpenes
Are essential oils stronger against gram-positive or negative bacteria?
Gram-positive bacteria
Have essential oils been studied for effectiveness against viruses?
No
These are mixtures of hydrocarbons extracted from plants
Essential oils
These have been used for centuries in traditional medicine and for preserving food
Essential oils
The microbial action of these is primarily due to phenolics and terpenes
Essential oils
These are stronger against gram-positive bacteria and have not yet been studied for their effectiveness against viruses
Essential oils
What are two halogens used in disinfectants?
Iodine and chlorine
What is an iodine tincture?
Solution in aqueous alcohol
What is iodophor?
Iodine combined with organic molecules for slow release
How do iodine disinfectants work?
By impairing protein synthesis and altering membranes
How do chlorine disinfectants work?
They are oxidizing agents that shut down cellular enzyme systems
What is chloramine?
Chlorine and ammonia
This is a solution of iodine in aqueous alcohol
Tincture
This is iodine combined with organic molecules for the slow release of iodine
Iodophor
This halogen impairs protein synthesis and alters membranes
Iodine
This halogen is an oxidizing agent
Chlorine
This halogen shuts down cellular enzyme systems
Chlorine
What is bleach?
Hypochlorous acid (HOCl)
What is chlorine + ammonia?
Chloramine
What is hypochlorous acid (HOCl) also known as?
Bleach
How do alcohols work as disinfectants?
Denature proteins and dissolve lipids
Can alcohols kill endospores?
No
Can alcohols kill enveloped viruses?
Yes
Can alcohols kill nonenveloped viruses?
No
What are two examples alcohols used as disinfectants?
Ethanol and isopropanol
Do ethanol and isopropanol require water to be more effective?
Yes
These disinfectants denature proteins, dissolve lipids, and require water to be more effective
Alcohols
These disinfectants have no effect on endospores and nonenveloped viruses
Alcohols
What does having oligodynamic action mean?
Very small amounts exert antimicrobial activity
How do heavy metals and their compounds work as disinfectants?
Denature proteins
What are four examples of heavy metals used as disinfectants?
Ag, Hg, Cu, Zn
What is silver nitrate used for?
Preventing opthalmia neonatorum
What is mercuric chloride used for?
Preventing mildew in paint
What is copper sulfate used for?
Algicide
What is zinc chloride used in?
Mouthwash
These disinfectants have oligodynamic action and denature proteins
Heavy metals and their compounds
This heavy metal disinfectant is used to prevent opthalmia neonatorum
Silver nitrate
This heavy metal disinfectant is added to paint to prevent mildew
Mercuric chloride
This heavy metal disinfectant is an algicide
Copper sulfate
This heavy metal disinfectant is found in mouthwash
Zinc chloride
How do surface-active agents work?
Decrease surface tension among molecules of liquid
What are the most common surface-active agents?
Soaps and detergents
What two properties does soap have as a disinfectant?
Degerming and emulsification
How do acid-anionic sanitizers work?
Anions react with plasma membrane
How do quaternary ammonium compounds (quats) work?
Cations are bactericidal, denature proteins, and disrupt plasma membrane
This group of disinfectants decrease surface tension among liquid molecules; the most common are soaps and detergents
Surface-active agents
This type of surface-active agent degerms and emulsifies
Soap
This type of surface-active agent has anions that react with the plasma membrane
Acid-anionic sanitizer
These surface-active agents have bactericidal cations, denature proteins, and disrupt plasma membranes
Quaternary ammonium compounds (quats)
What is sulfur dioxide used for?
Preventing wine spoilage
What three chemical food preservatives prevent molds in acidic foods?
Sorbic acid, benzoic acid, calcium propionate
Can our bodies easily metabolize chemical food preservatives?
Yes
How do nitrites and nitrates work in food preservation?
Preventing endospore germination
This chemical prevents wine spoilage
Sulfur dioxide
These are used for preserving specimens and in medical equipment
Aldehydes
These inhibit microbe metabolism, but our bodies easily metabolize them
Chemical food preservatives
These prevent endospore germination in foods
Nitrites and nitrates
What are bacteriocins?
Proteins produced by one bacterium that inhibits another
What are two antibiotics used to prevent cheese spoilage?
Nisin and natamycin (pimaricin)
These are proteins produced by one bacterium that inhibits another
Bacteriocins
These are two antibiotics that prevent the spoilage of cheese
Nisin and natamycin (pimaricin)
How do aldehydes work?
Inactivate proteins by cross-linking with functional groups
What are aldehydes used for?
Preserving specimens and in medical equipment
What are two examples of aldehydes
Formaldehyde and ortho-phthalaldehyde
What is one of the few liquid chemical sterilizing agents?
Glutaraldehyde
These inactivate proteins by cross-linking with functional groups
Aldehydes
This is one of the few liquid chemical sterilizing agents
Glutaraldehyde
These include formaldehyde and ortho-phthalaldehyde
Aldehydes
How does chemical sterilization work?
Gaseous sterilant causes alkylation and cross-links nucleic acids and proteins
What is alkylation?
Replacing hydrogen atoms of a chemical group with a free radical
What is chemical sterilization used for?
Heat-sensitive material
This process involves a gaseous sterilant causing alkylation and cross-linking nucleic acids and proteins
Chemical sterilization
What is plasma?
The fourth state of matter consisting of electrically excited gas
How does plasma work as a disinfectant?
Free radicals destroy microbes
What is plasma sterilization used to disinfect?
Tubular instruments
This is the fourth state of matter and consists of electrically excited gas
Plasma
This involves free radicals destroying microbes and is used for tubular instruments
Plasma sterilization
What is the process of supercritical fluids sterilization?
Substances are passed through a screenlike material
What type of materials are supercritical fluids used to disinfect?
Heat-sensitive materials
Does supercritical fluid sterilization combine chemical and physical methods?
Yes
This sterilization method compressed CO2, resulting in gaseous and liquid properties
Supercritical fluid sterilization
This sterilization method is used for medical implants
Supercritical fluid sterilization
In this sterilization method, chemical and physical methods are combined and substances are passed through a screenlike material
Supercritical fluid sterilization
What are peroxygens and other forms of oxygen used to sterilized?
Contaminated surfaces and food packaging
How do peroxygens/other oxygen forms work?
By ionizing water to create reactive hydroxyl radicals
What are three types of reactive hydroxyl radicals?
O3, H2O2, and peracetic acids (PAA)
What is PAA effective at killing?
Endospores
These are oxidizing agents that are used to sterilize contaminated surfaces and food packaging
Peroxygens and other forms of oxygen
Are peroxygens and other forms of oxygen oxidizing agents?
Yes
These chemical disinfectants ionize water to create reactive hydroxyl radicals O3, H2O2 and peracetic acid (PAA)
Peroxygens and other forms of oxygen
This reactive hydroxyl radical is effective on endospores
Peracetic acid (PAA)
Do biocides tend to be more effective against gram-positive or gram-negative bacteria?
Gram-positive bacteria
Mycobacteria, endospores, and protozoans’ cysts and oocytes are very resistant to these
Disinfectants and antiseptics
Are nonenveloped viruses generally more resistant than enveloped viruses?
Yes
Are prions resistant?
Yes
These four types of microbes are very resistant to disinfectants and antiseptics
Mycobacteria, endospores, protozoan cysts and oocytes
