Chapter 9 Flashcards
Process that destroys or removes all viable microorganisms (including viruses)
Sterilization
Examples of sterilizing agents
Heat (autoclave)
Sterilants (chemical agents capable of destroying endospores)
Physical process or a chemical agent that destroys vegetative pathogens but not bacterial endospores; removes harmful products of microorganisms (toxins) from material
Disinfection
Examples of disinfection agents
Bleach
Iodine
Heat (boiling)
Cleansing technique that mechanically removes microorganisms as well as other debris to reduce contamination to safe levels
*important to restaurants, dairies, breweries, and other commercial entities
Contamination/Sanitization
Examples of contamination/sanitization agents
soaps
detergents
commercial dishwashers
Reduces the number of microbes on the human skin; a form of decontamination but on LIVING tissues
Antisepsis/Degermation
Examples of antisepsis/degermation agents
alcohol
surgical hand scrub
Microbe that is extraordinarily resistant to heat and chemicals
prions
toughest form of microbial life
bacterial endospores
chemical that destroys bacteria except those in the endospore stag
Bactericide
having the capacity to kill bacteria is __________
having the capacity to interfere with bacteria reproduction is _______
- bactericidal
2. bacteristatic
a chemical that can kill fungal spores, hyphae, and yeasts
fungicide
any chemical known to inactivate viruses, especially on living tissue
virucide
an agent capable of destroying bacterial endospores
sporicide
an agent lethal to non-endospore-forming pathogens
germicide
chemicals that kill microorganisms
microbicides
defined as the growth of microorganisms in the blood and other tissues
sepsis
refers to any practice that prevents the entry of infectious agents into sterile tissues and therefore prevents infection
asepsis
a growth-inhibiting agent used on tissues to prevent infection
antiseptic
agents that prevent the growth of bacteria on tissues or on objects in the environment.
bacterisatic
medical devices that are expected to come into contact with sterile tissue, ie. syringe needle or artificial hip
; must be sterilized
Critical medical devices
medical devices that come into contact with mucosal membranes, ie. endoscopy tube
; must receive high-level disinfection and preferably sterilization
semicritical medical devices
medical devices that do not touch the patient or are only expected to touch intact skin, ie. blood pressure cuffs or crutches
; require low level disinfection (unless they become contaminated with blood or body fluids)
noncritical medical devices
autoclaving
steam sterilization
phenomenon that involves the permanent termination of an organism’s vital processes
death
Why is microbial death of an organism composed of just one or a few cells hard to detect?
b/c they reveal no conspicuous vital signs to begin with
Why is microbial death of an organism composed of just one or a few cells hard to detect?
b/c they reveal no conspicuous vital signs to begin with
What is the accepted microbiological definition of death?
permanent loss of reproductive capability even under optimum conditions
What factors influence the effectiveness of antimicrobial agents?
of micros
nature of micros (all different kinds?)
temperature/pH of environment
concentration (dosage/density) of the agent
mode of action of the agent (how does it kill or inhibit?)
presence of solvents, interfering organic matter, and inhibitors
an antimicrobial agent’s adverse effect on cells is called its
mode or mechanism of action
what are the four general categories of cellular targets of physical and chemical agents
- cell wall
- cytoplasmic membrane
- cellular synthetic processes (DNA, RNA)
- proteins
effects of agents on CELL WALL
blocking its synthesis or digesting it
ie. alcohol, detergents, chemicals
effects of agents on CYTOPLASMIC MEMBRANE
agents disrupt the lipid layer which opens up the membrane and allows damaging chemicals to enter the cell and important ions to exit the cell
ie. alcohol and detergents
effects of agents on CELLULAR SYNTHESIS
disrupt synthesis via the ribosomes which inhibits proteins needed for growth and metabolism and prevents multiplication
agents can also change genetic codes (mutation)
ie. formaldehyde, radiation, ethylene oxide
effects of agents on PROTEINS
denaturing of proteins
prevents some proteins from interacting with their chemical substrates
ie. moist heat, alcohol, phenolics
SARS-CoV-2 is an _________ virus, and its ______ is susceptible to both detergents and alcohol.
- enveloped
2. envelope
least resistant microbial entities
vegetative forms of cells
The vast majority of microbes in the same environment that humans live in can be controlled by
abrupt changes in their environment, such as heat
elevated temperatures that exceed the maximum growth temp are
microbicidial
lower temperatures below the minimum growth temp are
microbistatic
what is the temp range for moist heat?
60-135 dgerees Celsius
dry heat refers to hot air such as in an oven, and its temp range is
160 degrees to several thousand degrees Celsius
_____ heat can achieve the same effectiveness as ___ heat but with lower temperatures and and SHORTER exposure time
- Moist
2. Dry
Effect of moist heat
damages many cellular structures
but its most lethal effect is the denaturation and coagulation of proteins which QUICKLY/PERMANENTLY halts cellular metabolism
with MOIST heat, how long does it take to sterilize at 134 degrees C?
3 minutes
With DRY heat, how long does it take to sterilize at 140 degrees C?
180 minutes
How does dry heat effect cells?
dehydrates the cell, removing necessary water for metabolic reactions
also denatures proteins
*However, lack of water can actually increase the stability of some protein conformations
At very high heat what does DRY heat do to cells?
It oxidizes them and burns them to ashes, which is used in incineration in the medical industry or when a loop is flamed
which two microbes in their vegetative form are the least resistant to most and dry heat?
Which microbe exhibits the greatest resistance to moist and dry heat?
bacteria and fungi
bacterial endospores
destruction of endospores requires temps above ________
boiling
viruses are surprisingly resistant to ______.
Hepatitis A virus can tolerate _____ at 60 degrees C for 600 minutes.
heat
defined as the shortest length of time required to kill all test microbes at a specified temperature; is a combination of two variables- heat and time.
Thermal death time (TDT)
defined as the lowest temperature required to kill all microbes in a sample in 10 minutes
Thermal death point (TDP)
commercial canneries heat low-acid foods at 121 degrees C for 30 minutes, because this _______ food
sterilizes
boiling water is a mode of _________
disinfection
Pasteurization is a mode that ________
disinfects
steam under pressure (autoclaving) is a form of _______
sterilization
Incineration and hot air oven heat are forms of
sterilization
principal benefit of cold treatment
slow down the growth of cultures and microbes during food processing and storage
*is microbistatic
to dry thoroughly; to preserve by drying
desiccation
some pathogens die after hours of air drying such as streptococcus pneumoniae, but many are not killed and some are ________
preserved
_______ can be a valuable way to preserve foods because it greatly reduces the amount of water available for microbial growth
Desiccation
combination of freezing and drying that is a common method of preserving microorganisms and other cells in a viable state for many years
lyophilization
As a general rule _________, ____________, and ______________ should not be construed methods of disinfection and sterilization because there antimicrobial effects are erratic and uncertain.
freezing, chilling, and desiccation
defined as energy emitted from atomic activities and dispersed at high velocity through matter or space
radiation
order the different types of radiation from smallest energy to increasing energy
UV -> X rays -> Gamma rays
list two types of ionizing radiation and what they do
gamma and x rays
->highly effective in sterilizing
the application of radiant energy for diagnosis, therapy, disinfection, or sterilization
irradiation
_____ radiation ranges in wavelength from approximately 100-400nm (most lethal from 240-280nm); works to disinfect and can cutdown airborne microbes as much as 99%
ultraviolet
how does UV radiation damage cells?
causes inappropriate formation of bonds between two adjacent bases on a DNA strand
______ in an effective physical method to remove microbes from the air and liquids; fluid or air is trained through a filter with openings large enough for fluid to pass through but too small for microorganisms to pass through
filtration
most modern microbiological ________ are thin membranes of cellulose acetate, polycarbonate, and a variety of plastic material (Teflon, nylon) whose pore size can be carefully controlled and standardized.
filters
filtration is used to prepare liquids that cannot withstand _______, including serum and other blood products, vaccines, drugs, IV fluids, enzymes, and media.
heat
adding large amounts salt or sugar to foods creates a __________ environment for bacteria in the foods, causing plasmolysis and making it impossible for the bacteria to multiply
hypertonic
solutions containing pure water as a solvent are termed
aqueous
solutions containing pure alcohol or alcohol-water mixtures are termed
tinctures
list desirable qualities in a germicide
rapid action in low concentrations
solubility in water or alcohol and long term stability
broad-spectrum microbicidal action without being toxic to human and animal tissues
penetration of inanimate surfaces without being toxic to human and animal tissues
resistance to becoming inactivated by organic matter
not corrosive and non-staining
sanitizing and deodorizing properties
affordable and available
High-level germicides
kill endospores and are sterilants
intermediate-level germicides
kill fungal spores and resistant pathogens such as the bacterium that causes tuberculosis, and viruses
low level germicides
eliminate vegetative bacteria, vegetative fungal cells, and some viruses
-clean straps, electrodes, furniture that touches skin
what are some organisms that CHLORINE destructs
mycobacterium tuberculosis
entamoeba cysts (protozoa)
Hep A virus
what are some organisms that ETHYL ALCOHOL destructs
Staphylococcus aureus
Escherichia coli
Poliovirus
what are some organisms that HYDROGEN PEROXIDE destructs
Staphylococcus aureus
Neisseria gonorrhoeae
Herpes simplex virus
what are some organisms that QUATERNARY AMMONIUM COMPOUND destructs
Staphylococcus aureus
Salmonella typhi
what are some organisms that ETHYLENE OXIDE GAS destructs
Streptococcus faecalis Influenza virus (10,000 mg/L concentration kills virus in 25 hours)
Would an enveloped or non-enveloped virus be inactivated by a alcohol based hand wash?
Enveloped because it is a membrane, and alcohol’s major action is to dissolve membrane lipids
Germicidal Categories According to Chemical Group
Chlorine
Halogen
- can slowly kill endospores; kills all other microbes
- suspends metabolic reactions
- less effective if exposed to light, excessive organic matter, and alkaline pH
- capable of sterilization
Germicidal Categories According to Chemical Group
Iodine
Halogen
-can kill endospores and all other microbes
-interferes with hydrogen and disulfide bonding of proteins
-can be extremely irritating to the skin
(many iodophors banned in 2017)
-sterilization
Germicidal Categories According to Chemical Group
Oxidizing agents
HYDROGEN PEROXIDE
- kill endospores and all other microbes
- oxygen forms free radicals which are highly toxic/reactive to cells
- sporicidal only in high concentrations
- sterilization
Germicidal Categories According to Chemical Group
Aldehydes
- kill endospores and all other microbes
- disrupts the activity of enzymes and other proteins within the cell
- Glutaraldehyde is broad spectrum and kills rapidly
- sterilization
Germicidal Categories According to Chemical Group
Gaseous sterilant/disinfectants
- ethylene oxide kills endospores; other gases are less effective
- reacts with functional groups of DNA and proteins and blocks both DNA replication and enzymatic action
- ethylene oxide is explosive
- used on syringes, surgical supplies, etc.
- sterilization
- can damage lungs, eyes, mucous membrane if direct contact
*Ethylene oxide is rated as a carcinogen by the gov
Germicidal Categories According to Chemical Group
Phenol (carbolic acid)
- kills some bacteria, fungi, viruses
- in high concentrations they are cellular poisons disrupting cell walls and membrane proteins
- in low concentrations they inactivate certain critical enzyme systems
- many phenols banned in consumer products in 2017
Germicidal Categories According to Chemical Group
Chlorhexidine
- kills most bacteria, viruses, fungi
- targets bacterial membranes, where selective permeability is lost, bacterial cells walls, and proteins, resulting in denaturation
Germicidal Categories According to Chemical Group
Alcohol
- kills most bacteria, viruses, fungi
- dissolves membrane lipids/compromises membrane integrity
Germicidal Categories According to Chemical Group
Detergents
- kills some bacteria viruses and fungi
- disrupts cytoplasmic membrane through proteins
Germicidal Categories According to Chemical Group
Heavy Metal Compounds
- kills some bacteria, viruses, fungi
- bind to functional groups of proteins and inactivate them
- not effective against endospores
- can be toxic to inhale, ingest, and absorb
Germicidal Categories According to Chemical Group
Acids and Alkalis
- kills some bacteria, fungi, and viruses
- alters pH
- large pH changes can be corrosive
What method would you use following a surgical procedure to sterilize medical equipment?
a. Filtration
b. Autoclaving
c. Incineration
d. Radiation
b. Autoclaving
give an example of when Chlorhexidine is used
to rinse the mouth during times when a tube is inserted into the mouth or nose for a ventilator, this way it can kill microbes and prevent them from migrating to the lungs
-chlorhexidine targets bacterial cell walls and membranes, as well as proteins
DNA repair mechanisms can help alleviate the effects of
a. UV radiation
b. Alcohol disinfection
c. Autoclaving
d. Dry heat
a. UV radiation
Cytoplasmic enzymes are most likely to be disrupted by
a. UV light
b. Low temps
c. High temps
d. Detergents
c. High temps
Transcription is targeted most directly by
a. Quats
b. Detergents
c. UV radiation
d. Alcohol
c. UV radiation
peracetic acid
hydrogen peroxide
The most versatile method for sterilizing heat-sensitive liquids is
a. UV radiation
b. exposure to ozone
c. peracetic acid
d. filtration
d. filtration
